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1. Time-series and Phasecurve Photometry of Episodically-Active Asteroid (6478) Gault in a Quiescent State Using APO, GROWTH, P200 and ZTF

Author

Purdum, Josiah N., Lin, Zhong-Yi, Bolin, Bryce T., Sharma, Kritti, Choi, Philip I., Bhalerao, Varun, Kumar, Harsh, Quimby, Robert, Van Roestel, Joannes C., Zhai, Chengxing, Fernandez, Yanga R., Hanuš, Josef, Lisse, Carey M., Bodewits, Dennis, Fremling, Christoffer, Golovich, Nathan Ryan, Hsu, Chen-Yen, Ip, Wing-Huen, Ngeow, Chow-Choong, Saini, Navtej S., Shao, Michael, Yao, Yuhan, Ahumada, Tomás, Anand, Shreya, Andreoni, Igor, Burdge, Kevin B., Burruss, Rick, Chang, Chan-Kao, Copperwheat, Chris M., Coughlin, Michael, De, Kishalay, Dekany, Richard, Delacroix, Alexandre, Drake, Andrew, Duev, Dmitry, Graham, Matthew, Hale, David, Kool, Erik C., Kasliwal, Mansi M., Kostadinova, Iva S., Kulkarni, Shrinivas R., Laher, Russ R., Mahabal, Ashish, Masci, Frank J., Mróz, Przemyslaw J., Neill, James D., Riddle, Reed, Rodriguez, Hector, Smith, Roger M., Walters, Richard, Yan, Lin, and Zolkower, Jeffry

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

We observed Episodically Active Asteroid (6478) Gault in 2020 with multiple telescopes in Asia and North America and have found that it is no longer active after its recent outbursts at the end of 2018 and start of 2019. The inactivity during this apparation allowed us to measure the absolute magnitude of Gault of H_r = 14.63 +/- 0.02, G_r = 0.21 +/- 0.02 from our secular phasecurve observations. In addition, we were able to constrain Gault's rotation period using time-series photometric lightcurves taken over 17 hours on multiple days in 2020 August, September and October. The photometric lightcurves have a repeating $\lesssim$0.05 magnitude feature suggesting that (6478) Gault has a rotation period of ~2.5 hours and may have a semi-spherical or top-like shape, much like Near-Earth Asteroids Ryugu and Bennu. The rotation period of ~2.5 hours is near to the expected critical rotation period for an asteroid with the physical properties of (6478) Gault suggesting that its activity observed over multiple epochs is due to surface mass shedding from its fast rotation spun up by the Yarkovsky-O'Keefe-Radzievskii-Paddack effect., Comment: 23 pages, 18 figures; Accepted by ApJ Letters

Published
2021
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2. Initial Characterization of Active Transitioning Centaur, P/2019 LD2 (ATLAS), using Hubble, Spitzer, ZTF, Keck, APO and GROWTH Visible & Infrared Imaging and Spectroscopy

Author

Bolin, Bryce T., Fernandez, Yanga R., Lisse, Carey M., Holt, Timothy R., Lin, Zhong-Yi, Purdum, Josiah N., Deshmukh, Kunal P., Bauer, James M., Bellm, Eric C., Bodewits, Dennis, Burdge, Kevin B., Carey, Sean J., Copperwheat, Chris M., Helou, George, Ho, Anna Y. Q., Horner, Jonathan, van Roestel, Jan, Bhalerao, Varun, Chang, Chan-Kao, Chen, Christine, Hsu, Chen-Yen, Ip, Wing-Huen, Kasliwal, Mansi M., Masci, Frank J., Ngeow, Chow-Choong, Quimby, Robert, Burruss, Rick, Coughlin, Michael, Dekany, Richard, Delacroix, Alexandre, Drake, Andrew, Duev, Dmitry A., Graham, Matthew, Hale, David, Kupfer, Thomas, Laher, Russ R., Mahabal, Ashish, Mróz, Przemyslaw J., Neill, James D., Riddle, Reed, Rodriguez, Hector, Smith, Roger M., Soumagnac, Maayane T., Walters, Richard, Yan, Lin, and Zolkower, Jeffry

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

We present visible and mid-infrared imagery and photometry of temporary Jovian co-orbital comet P/2019 LD$_2$ taken with HST/WFC3, Spitzer/IRAC, the GROWTH telescope network, visible spectroscopy from Keck/LRIS and archival ZTF observations taken between 2019 April and 2020 August. Our observations indicate that the nucleus of LD$_2$ has a radius between 0.2-1.8 km assuming a 0.08 albedo and a coma dominated by $\sim$100$\mu$ m-scale dust ejected at $\sim$1 m/s speeds with a $\sim$1'' jet pointing in the SW direction. LD$_2$ experienced a total dust mass loss of $\sim$10$^8$ kg at a loss rate of $\sim$6 kg/s with Af$\rho$/cross-section varying between $\sim$85 cm/125 km$^2$ and $\sim$200 cm/310 km$^2$ from 2019 April 9 to 2019 Nov 8. If the increase in Af$\rho$/cross-section remained constant, it implies LD$_2$'s activity began $\sim$2018 November when within 4.8 au of the Sun, implying the onset of H$_2$O sublimation. We measure CO/CO$_2$ gas production of $\lesssim$10$^{27}$ mol/s /$\lesssim$10$^{26}$ mol/s from our 4.5 $\mu$m Spitzer observations, $g$-$r$ = 0.59$\pm$0.03, $r$-$i$ = 0.18$\pm$0.05, $i$-$z$ = 0.01$\pm$0.07 from GROWTH observations, H$_2$O gas production of $\lesssim$80 kg/s scaling from our estimated $C_2$ production of $Q_{C_2}\lesssim$7.5$\times10^{24}$ mol/s from Keck/LRIS spectroscopy. We determine that the long-term orbit of LD$_2$ is similar to Jupiter family comets having close encounters with Jupiter within $\sim$0.5 Hill radius in the last $\sim$3 y, within 0.8 Hill radius in $\sim$9 y. Additionally, 78.8$\%$ of our orbital clones are ejected from the Solar System within $1 \times 10^{6}$ years having a dynamical half-life of 3.4 $\times 10^5$ years., Comment: 28 pages, 8 figures, 2 Tables, accepted for publication in AJ

Published
2020
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3. Characterization of Temporarily-Captured Minimoon 2020 CD$_3$ by Keck Time-resolved Spectrophotometry

Author

Bolin, Bryce T., Fremling, Christoffer, Holt, Timothy R., Hankins, Matthew J., Ahumada, Tomás, Anand, Shreya, Bhalerao, Varun, Burdge, Kevin B., Copperwheat, Chris M., Coughlin, Michael, Deshmukh, Kunal P., De, Kishalay, Kasliwal, Mansi M., Morbidelli, Alessandro, Purdum, Josiah N., Quimby, Robert, Bodewits, Dennis, Chang, Chan-Kao, Ip, Wing-Huen, Hsu, Chen-Yen, Laher, Russ R., Lin, Zhong-Yi, Lisse, Carey M., Masci, Frank J., Ngeow, Chow-Choong, Tan, Hanjie, Zhai, Chengxing, Burruss, Rick, Dekany, Richard, Delacroix, Alexandre, Duev, Dmitry A., Graham, Matthew, Hale, David, Kulkarni, Shrinivas R., Kupfer, Thomas, Mahabal, Ashish, Mróz, Przemyslaw J., Neill, James D., Riddle, Reed, Rodriguez, Hector, Smith, Roger M., Soumagnac, Maayane T., Walters, Richard, Yan, Lin, and Zolkower, Jeffry

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

We present time-resolved visible spectrophotometry of minimoon 2020 CD$_3$, the second asteroid known to become temporarily captured by the Earth-Moon system's gravitational field. The spectrophotometry was taken with Keck I/LRIS between wavelengths 434 nm and 912 nm in $B$, $g$, $V$, $R$, $I$ and RG850 filters as it was leaving the Earth-Moon system on 2020 March 23 UTC. The spectrophotometry of 2020 CD$_3$ most closely resembles the spectra of V-type asteroids and some Lunar rock samples with a reddish slope of ~18$\%$/100 nm between 434 nm and 761 nm corresponding to colors of $g$-$r$ = 0.62$\pm$0.08, $r$-$i$ = 0.21 $\pm$ 0.06 and an absorption band at ~900 nm corresponding to $i$-$z$ = -0.54$\pm$0.10. Combining our measured 31.9$\pm$0.1 absolute magnitude with an albedo of 0.35 typical for V-type asteroids, we determine 2020 CD$_3$'s diameter to be ~0.9$\pm$0.1 m making it the first minimoon and one of the smallest asteroids to be spectrally studied. We use our time-series photometry to detect periodic lightcurve variations with a $<$10$^{-4}$ false alarm probability corresponding to a lightcurve period of ~573 s and a lightcurve amplitude of ~1 mag implying 2020 CD$_3$ possesses a $b/a$ axial ratio of ~2.5. In addition, we extend the observational arc of 2020 CD$_3$ to 37 days between 2020 February 15 UTC and 2020 March 23 UTC. From the improved orbital solution for 2020 CD$_3$, we estimate its likely duration of its capture to be ~2 y, and we measure the non-gravitation perturbation on its orbit due to radiation pressure with an area-to-mass ratio of 6.9$\pm$2.4$\times$10$^{-4}$ m$^2$/kg implying a density of 2.3$\pm$0.8 g/cm$^3$, broadly compatible with the densities of other meter-scale asteroids and Lunar rock. We searched for pre-discovery detections of 2020 CD$_3$ in the ZTF archive as far back as 2018 October, but were unable to locate any positive detections., Comment: 26 pages, 8 figures, 3 Tables, accepted for publication in ApJL

Published
2020

4. Characterization of a dual-beam, dual-camera optical imaging polarimeter

Author

Shrestha, Manisha, Steele, Iain A., Piascik, Andrez S., Jermak, Helen, Smith, Robert J., and Copperwheat, Chris M.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

Polarization plays an important role in various time-domain astrophysics to understand the magnetic fields, geometry, and environments of spatially unresolved variable sources. In this paper we present the results of laboratory and on-sky testing of a novel dual-beam, dual-camera optical imaging polarimeter (MOPTOP) exploiting high sensitivity, low-noise CMOS technology and designed to monitor variable and transient sources with low systematic errors and high sensitivity. We present a data reduction algorithm that corrects for sensitivity variations between the cameras on a source-by-source basis. Using our data reduction algorithm, we show that our dual-beam, dual-camera technique delivers the benefits of low and stable instrumental polarization ($<0.05$\% for lab data and $<0.25$\% for on sky data) and high throughput while avoiding the additional sky brightness and image overlap problems associated with dual-beam, single-camera polarimeters., Comment: 12 pages, 11 figures, Accepted for publication in MNRAS

Published
2020
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5. The First Post-Kepler Brightness Dips of KIC 8462852

Author

Boyajian, Tabetha S., Alonso, Roi, Ammerman, Alex, Armstrong, David, Ramos, A. Asensio, Barkaoui, K., Beatty, Thomas G., Benkhaldoun, Z., Benni, Paul, Bentley, Rory, Berdyugin, Andrei, Berdyugina, Svetlana, Bergeron, Serge, Bieryla, Allyson, Blain, Michaela G., Blanco, Alicia Capetillo, Bodman, Eva H. L., Boucher, Anne, Bradley, Mark, Brincat, Stephen M., Brink, Thomas G., Briol, John, Brown, David J. A., Budaj, J., Burdanov, A., Cale, B., Carbo, Miguel Aznar, Garcia, R. Castillo, Clark, Wendy J, Clayton, Geoffrey C., Clem, James L., Coker, Phillip H, Cook, Evan M., Copperwheat, Chris M., Curtis, J., Cutri, R. M., Cseh, B., Cynamon, C. H., Daniels, Alex J., Davenport, James R. A., Deeg, Hans J., De Lorenzo, Roberto, De Jaeger, Thomas, Desrosiers, Jean-Bruno, Dolan, John, Dowhos, D. J., Dubois, Franky, Durkee, R., Dvorak, Shawn, Easley, Lynn, Edwards, N., Ellis, Tyler G., Erdelyi, Emery, Ertel, Steve, Farfán, Rafael. G., Farihi, J., Filippenko, Alexei V., Foxell, Emma, Gandolfi, Davide, Garcia, Faustino, Giddens, F., Gillon, M., González-Carballo, Juan-Luis, González-Fernández, C., Hernández, J. I. González, Graham, Keith A., Greene, Kenton A., Gregorio, J., Hallakoun, Na'ama, Hanyecz, Ottó, Harp, G. R., Henry, Gregory W., Herrero, E., Hildbold, Caleb F., Hinzel, D., Holgado, G., Ignácz, Bernadett, Ivanov, Valentin D., Jehin, E., Jermak, Helen E., Johnston, Steve, Kafka, S., Kalup, Csilla, Kardasis, Emmanuel, Kaspi, Shai, Kennedy, Grant M., Kiefer, F., Kielty, C. L., Kessler, Dennis, Kiiskinen, H., Killestein, T. L., King, Ronald A., Kollar, V., Korhonen, H., Kotnik, C., Könyves-Tóth, Réka, Kriskovics, Levente, Krumm, Nathan, Krushinsky, Vadim, Kundra, E., Lachapelle, Francois-Rene, Lacourse, D., Lake, P., Lam, Kristine, Lamb, Gavin P., Lane, Dave, Lau, Marie Wingyee, Lewin, Pablo, Lintott, Chris, Lisse, Carey, Logie, Ludwig, Longeard, Nicolas, Villanueva, M. Lopez, Ludington, E. Whit, Mainzer, A., Malo, Lison, Maloney, Chris, Mann, A., Mantero, A., Marengo, Massimo, Marchant, Jon, González, M. J. Martinez, Masiero, Joseph R., Mauerhan, Jon C., Mccormac, James, Mcneely, Aaron, Meng, Huan Y. A., Miller, Mike, Molnar, Lawrence A., Morales, J. C., Morris, Brett M., Muterspaugh, Matthew W., Nespral, David, Nugent, C. R., Nugent, Katherine M., Odasso, A., O'keeffe, Derek, Oksanen, A., O'meara, John M., Ordasi, András, Osborn, Hugh, Ott, John J., Parks, J. R., Perez, Diego Rodriguez, Petriew, Vance, Pickard, R., Pál, András, Plavchan, P., Plaza, C. Westendorp, Pollacco, Don, Nuñez, F. Pozo, Pozuelos, F. J., Rau, Steve, Redfield, Seth, Relles, Howard, Ribas, I., Richards, Jon, Saario, Joonas L. O., Safron, Emily J., Sallai, J. Martin, Sárneczky, Krisztián, Schaefer, Bradley E., Schumer, Clea F., Schwartzendruber, Madison, Siegel, Michael H., Siemion, Andrew P. V., Simmons, Brooke D., Simon, Joshua D., Simón-Diaz, S., Sitko, Michael L., Socas-Navarro, Hector, Sódor, Á., Starkey, Donn, Steele, Iain A., Stone, Geoff, Street, R. A., Sullivan, Tricia, Suomela, J., Swift, J. J., Szabó, Gyula M., Szabó, Róbert, Szakáts, Róbert, Szalai, Tamás, Tanner, Angelle M., Toledo-Padrón, B., Tordai, Tamás, Triaud, Amaury H. M. J., Turner, Jake D., Ulowetz, Joseph H., Urbanik, Marian, Vanaverbeke, Siegfried, Vanderburg, Andrew, Vida, Krisztián, Vietje, Brad P., Vinkó, József, Von Braun, K., Waagen, Elizabeth O., Walsh, Dan, Watson, Christopher A., Weir, R. C., Wenzel, Klaus, Williamson, Michael W., Wright, Jason T., Wyatt, M. C., Zheng, Weikang, and Zsidi, Gabriella

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract

We present a photometric detection of the first brightness dips of the unique variable star KIC 8462852 since the end of the Kepler space mission in 2013 May. Our regular photometric surveillance started in October 2015, and a sequence of dipping began in 2017 May continuing on through the end of 2017, when the star was no longer visible from Earth. We distinguish four main 1-2.5% dips, named "Elsie," "Celeste," "Skara Brae," and "Angkor", which persist on timescales from several days to weeks. Our main results so far are: (i) there are no apparent changes of the stellar spectrum or polarization during the dips; (ii) the multiband photometry of the dips shows differential reddening favoring non-grey extinction. Therefore, our data are inconsistent with dip models that invoke optically thick material, but rather they are in-line with predictions for an occulter consisting primarily of ordinary dust, where much of the material must be optically thin with a size scale <<1um, and may also be consistent with models invoking variations intrinsic to the stellar photosphere. Notably, our data do not place constraints on the color of the longer-term "secular" dimming, which may be caused by independent processes, or probe different regimes of a single process., Comment: 19 pages, 8 figures, accepted for publication in ApJL

Published
2018
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6. Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1

Author

Gillon, Michael, Triaud, Amaury H. M. J., Demory, Brice-Olivier, Jehin, Emmanuel, Agol, Eric, Deck, Katherine M., Lederer, Susan M., de Wit, Julien, Burdanov, Artem, Ingalls, James G., Bolmont, Emeline, Leconte, Jeremy, Raymond, Sean N., Selsis, Franck, Turbet, Martin, Barkaoui, Khalid, Burgasser, Adam, Burleigh, Matthew R., Carey, Sean J., Chaushev, Aleksander, Copperwheat, Chris M., Delrez, Laetitia, Fernandes, Catarina S., Holdsworth, Daniel L., Kotze, Enrico J., Van Grootel, Valerie, Almleaky, Yaseen, Benkhaldoun, Zouhair, Magain, Pierre, and Queloz, Didier

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

One focus of modern astronomy is to detect temperate terrestrial exoplanets well-suited for atmospheric characterisation. A milestone was recently achieved with the detection of three Earth-sized planets transiting (i.e. passing in front of) a star just 8% the mass of the Sun 12 parsecs away. Indeed, the transiting configuration of these planets with the Jupiter-like size of their host star - named TRAPPIST-1 - makes possible in-depth studies of their atmospheric properties with current and future astronomical facilities. Here we report the results of an intensive photometric monitoring campaign of that star from the ground and with the Spitzer Space Telescope. Our observations reveal that at least seven planets with sizes and masses similar to the Earth revolve around TRAPPIST-1. The six inner planets form a near-resonant chain such that their orbital periods (1.51, 2.42, 4.04, 6.06, 9.21, 12.35 days) are near ratios of small integers. This architecture suggests that the planets formed farther from the star and migrated inward. The seven planets have equilibrium temperatures low enough to make possible liquid water on their surfaces., Comment: 27 pages

Published
2017
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7. Spectroscopy of candidate electromagnetic counterparts to gravitational wave sources

Author

Steele, Iain A, Copperwheat, Chris M, and Piascik, Andrzej S

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

A programme of worldwide, multi-wavelength electromagnetic follow-up of sources detected by gravitational wave detectors is in place. Following the discovery of GW150914 and GW151226, wide field imaging of their sky localisations identified a number of candidate optical counterparts which were then spectrally classified. The majority of candidates were found to be supernovae at redshift ranges similar to the GW events and were thereby ruled out as a genuine counterpart. Other candidates ruled out include AGN and solar system objects. Given the GW sources were black hole binary mergers, the lack of an identified electromagnetic counterpart is not surprising. However the observations show that is it is possible to organise and execute a campaign that can eliminate the majority of potential counterparts. Finally we note the existence of a "classification gap" with a significant fraction of candidates going unclassified., Comment: 4 pages. Submitted to Proceedings of IAU Symposium 324 (New Frontiers in Black Hole Astrophysics). Minor revision

Published
2016
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8. Properties of the Eclipsing Double-White Dwarf Binary NLTT 11748

Author

Kaplan, David L., Marsh, Thomas R., Walker, Arielle N., Bildsten, Lars, Bours, Madelon C. P., Breedt, Elmé, Copperwheat, Chris M., Dhillon, Vik S., Howell, Steve B., Littlefair, Stuart P., Shporer, Avi, and Steinfadt, Justin D. R.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies
Abstract

We present high-quality ULTRACAM photometry of the eclipsing detached double-white dwarf binary NLTT 11748. This system consists of a carbon/oxygen white dwarf and an extremely-low mass (< 0.2 Msun) helium-core white dwarf in a 5.6 hr orbit. To date such extremely-low mass WDs, which can have thin, stably-burning outer layers, have been modeled via poorly-constrained atmosphere and cooling calculations where uncertainties in the detailed structure can strongly influence the eventual fates of these systems when mass-transfer begins. With precise (individual precision ~1%) high-cadence (~2 s) multi-color photometry of multiple primary and secondary eclipses spanning >1.5 yr, we constrain the masses and radii of both objects in the NLTT 11748 system to a statistical uncertainty of a few percent. However, we find that overall uncertainty in the thickness of the envelope of the secondary carbon/oxygen white dwarf leads to a larger (~13%) systematic uncertainty in the primary He WD's mass. Over the full range of possible envelope thicknesses we find that our primary mass (0.136-0.162 Msun) and surface gravity (log(g)=6.32-6.38; radii are 0.0423-0.0433 Rsun) constraints do not agree with previous spectroscopic determinations. We use precise eclipse timing to detect the Romer delay at 7 sigma significance, providing an additional weak constraint on the masses and limiting the eccentricity to e*cos(omega)= -4e-5 +/- 5e-5. Finally, we use multi-color data to constrain the secondary's effective temperature (7600+/-120 K) and cooling age (1.6-1.7 Gyr)., Comment: 10 pages, 6 figures. ApJ, in press. Minor typographical corrections in v2

Published
2013
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9. White Light Flare Continuum Observations with ULTRACAM

Author

Kowalski, Adam F., Mathioudakis, Mihalis, Hawley, Suzanne L., Hilton, Eric J., Dhillon, Vik S., Marsh, Tom R., and Copperwheat, Chris M.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

We present sub-second, continuous-coverage photometry of three flares on the dM3.5e star, EQ Peg A, using custom continuum filters with WHT/ULTRACAM. These data provide a new view of flare continuum emission, with each flare exhibiting a very distinct light curve morphology. The spectral shape of flare emission for the two large-amplitude flares is compared with synthetic ULTRACAM measurements taken from the spectra during the large 'megaflare' event on a similar type flare star. The white light shape during the impulsive phase of the EQ Peg flares is consistent with the range of colors derived from the megaflare continuum, which is known to contain a Hydrogen recombination component and compact, blackbody-like components. Tentative evidence in the ULTRACAM photometry is found for an anti-correlation between the emission of these components., Comment: 8 pages, 3 figures. Proceedings of the 16th Workshop on Cool Stars, Stellar Systems, and the Sun (PASP conference series, in press)

Published
2011

10. Initial Characterization of Active Transitioning Centaur, P/2019 LD₂ (ATLAS), Using Hubble, Spitzer, ZTF, Keck, Apache Point Observatory, and GROWTH Visible and Infrared Imaging and Spectroscopy

Author

Bolin, Bryce T., Fernandez, Yanga R., Lisse, Carey M., Holt, Timothy R., Lin, Zhong-Yi, Purdum, Josiah N., Deshmukh, Kunal P., Bauer, James M., Bellm, Eric C., Bodewits, Dennis, Burdge, Kevin B., Carey, Sean J., Copperwheat, Chris M., Helou, George, Ho, Anna Y. Q., Horner, Jonathan, van Roestel, Jan, Bhalerao, Varun, Chang, Chan-Kao, Chen, Christine, Hsu, Chen-Yen, Ip, Wing-Huen, Kasliwal, Mansi M., Masci, Frank J., Ngeow, Chow-Choong, Quimby, Robert, Burruss, Rick, Coughlin, Michael, Dekany, Richard, Delacroix, Alexandre, Drake, Andrew, Duev, Dmitry A., Graham, Matthew, Hale, David, Kupfer, Thomas, Laher, Russ R., Mahabal, Ashish, Mróz, Przemyslaw J., Neill, James D., Riddle, Reed, Rodriguez, Hector, Smith, Roger M., Soumagnac, Maayane T., Walters, Richard, Yan, Lin, and Zolkower, Jeffry

Abstract

We present visible and mid-infrared imagery and photometry of temporary Jovian co-orbital comet P/2019 LD₂ taken with Hubble Space Telescope/Wide Field Camera 3 (HST/WFC3), Spitzer Space Telescope/Infrared Array Camera (Spitzer/IRAC), and the GROWTH telescope network, visible spectroscopy from Keck/Low-Resolution Imaging Spectrometer (LRIS), and archival Zwicky Transient Facility observations taken between 2019 April and 2020 August. Our observations indicate that the nucleus of LD₂ has a radius between 0.2 and 1.8 km assuming a 0.08 albedo and a coma dominated by ~100 μm-scale dust ejected at ~1 m s⁻¹ speeds with a ~1' jet pointing in the southwest direction. LD₂ experienced a total dust mass loss of ~10⁸ kg at a loss rate of ~6 kg s⁻¹ with Afρ/cross section varying between ~85 cm/125 km² and ~200 cm/310 km² from 2019 April 9 to 2019 November 8. If the increase in Afρ/cross section remained constant, it implies LD₂'s activity began ~2018 November when within 4.8 au of the Sun, implying the onset of H₂O sublimation. We measure CO/CO₂ gas production of ≾10²⁷ mol s⁻¹/≾10²⁶ mol s⁻¹ from our 4.5 μm Spitzer observations; g–r = 0.59 ± 0.03, r–i = 0.18 ± 0.05, and i–z = 0.01 ± 0.07 from GROWTH observations; and H₂O gas production of ≾80 kg s⁻¹ scaling from our estimated C₂ production of Q_(C₂) ≾7.5×10²⁴ mol s⁻¹ from Keck/LRIS spectroscopy. We determine that the long-term orbit of LD₂ is similar to Jupiter-family comets having close encounters with Jupiter within ~0.5 Hill radius in the last ~3 y and within 0.8 Hill radius in ~9 y. Additionally, 78.8% of our orbital clones are ejected from the solar system within 1 × 10⁶ yr, having a dynamical half-life of 3.4 × 10⁵ yr.

Published
2021

11. Time-series and Phase-curve Photometry of the Episodically Active Asteroid (6478) Gault in a Quiescent State Using APO, GROWTH, P200, and ZTF

Author

Purdum, Josiah N., Lin, Zhong-Yi, Bolin, Bryce T., Sharma, Kritti, Choi, Philip I., Bhalerao, Varun, Hanuš, Josef, Kumar, Harsh, Quimby, Robert, van Roestel, Joannes C., Zhai, Chengxing, Fernandez, Yanga R., Lisse, Carey M., Bodewits, Dennis, Fremling, Christoffer, Ryan Golovich, Nathan, Hsu, Chen-Yen, Ip, Wing-Huen, Ngeow, Chow-Choong, Saini, Navtej S., Shao, Michael, Yao, Yuhan, Ahumada, Tomás, Anand, Shreya, Andreoni, Igor, Burdge, Kevin B., Burruss, Rick, Chang, Chan-Kao, Copperwheat, Chris M., Coughlin, Michael, De, Kishalay, Dekany, Richard, Delacroix, Alexandre, Drake, Andrew, Duev, Dmitry, Graham, Matthew, Hale, David, Kool, Erik C., Kasliwal, Mansi M., Kostadinova, Iva S., Kulkarni, Shrinivas R., Laher, Russ R., Mahabal, Ashish, Masci, Frank J., Mróz, Przemyslaw J., Neill, James D., Riddle, Reed, Rodriguez, Hector, Smith, Roger M., Walters, Richard, Yan, Lin, Zolkower, Jeffry, Purdum, Josiah N., Lin, Zhong-Yi, Bolin, Bryce T., Sharma, Kritti, Choi, Philip I., Bhalerao, Varun, Hanuš, Josef, Kumar, Harsh, Quimby, Robert, van Roestel, Joannes C., Zhai, Chengxing, Fernandez, Yanga R., Lisse, Carey M., Bodewits, Dennis, Fremling, Christoffer, Ryan Golovich, Nathan, Hsu, Chen-Yen, Ip, Wing-Huen, Ngeow, Chow-Choong, Saini, Navtej S., Shao, Michael, Yao, Yuhan, Ahumada, Tomás, Anand, Shreya, Andreoni, Igor, Burdge, Kevin B., Burruss, Rick, Chang, Chan-Kao, Copperwheat, Chris M., Coughlin, Michael, De, Kishalay, Dekany, Richard, Delacroix, Alexandre, Drake, Andrew, Duev, Dmitry, Graham, Matthew, Hale, David, Kool, Erik C., Kasliwal, Mansi M., Kostadinova, Iva S., Kulkarni, Shrinivas R., Laher, Russ R., Mahabal, Ashish, Masci, Frank J., Mróz, Przemyslaw J., Neill, James D., Riddle, Reed, Rodriguez, Hector, Smith, Roger M., Walters, Richard, Yan, Lin, and Zolkower, Jeffry

Abstract

We observed the episodically active asteroid (6478) Gault in 2020 with multiple telescopes in Asia and North America and found that it is no longer active after its recent outbursts at the end of 2018 and the start of 2019. The inactivity during this apparition allowed us to measure the absolute magnitude of Gault of H ( r ) = 14.63 +/- 0.02, G ( r ) = 0.21 +/- 0.02 from our secular phase-curve observations. In addition, we were able to constrain Gault's rotation period using time-series photometric lightcurves taken over 17 hr on multiple days in 2020 August, September, and October. The photometric lightcurves have a repeating less than or similar to 0.05 mag feature suggesting that (6478) Gault has a rotation period of similar to 2.5 hr and may have a semispherical or top-like shape, much like the near-Earth asteroids Ryugu and Bennu. The rotation period of similar to 2.5 hr is near the expected critical rotation period for an asteroid with the physical properties of (6478) Gault, suggesting that its activity observed over multiple epochs is due to surface mass shedding from its fast rotation spin-up by the Yarkovsky-O'Keefe-Radzievskii-Paddack effect.

Published
2021
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12. Time-series and Phase-curve Photometry of the Episodically Active Asteroid (6478) Gault in a Quiescent State Using APO, GROWTH, P200, and ZTF

Author

Purdum, Josiah N., primary, Lin, Zhong-Yi, additional, Bolin, Bryce T., additional, Sharma, Kritti, additional, Choi, Philip I., additional, Bhalerao, Varun, additional, Hanuš, Josef, additional, Kumar, Harsh, additional, Quimby, Robert, additional, van Roestel, Joannes C., additional, Zhai, Chengxing, additional, Fernandez, Yanga R., additional, Lisse, Carey M., additional, Bodewits, Dennis, additional, Fremling, Christoffer, additional, Ryan Golovich, Nathan, additional, Hsu, Chen-Yen, additional, Ip, Wing-Huen, additional, Ngeow, Chow-Choong, additional, Saini, Navtej S., additional, Shao, Michael, additional, Yao, Yuhan, additional, Ahumada, Tomás, additional, Anand, Shreya, additional, Andreoni, Igor, additional, Burdge, Kevin B., additional, Burruss, Rick, additional, Chang, Chan-Kao, additional, Copperwheat, Chris M., additional, Coughlin, Michael, additional, De, Kishalay, additional, Dekany, Richard, additional, Delacroix, Alexandre, additional, Drake, Andrew, additional, Duev, Dmitry, additional, Graham, Matthew, additional, Hale, David, additional, Kool, Erik C., additional, Kasliwal, Mansi M., additional, Kostadinova, Iva S., additional, Kulkarni, Shrinivas R., additional, Laher, Russ R., additional, Mahabal, Ashish, additional, Masci, Frank J., additional, Mróz, Przemyslaw J., additional, Neill, James D., additional, Riddle, Reed, additional, Rodriguez, Hector, additional, Smith, Roger M., additional, Walters, Richard, additional, Yan, Lin, additional, and Zolkower, Jeffry, additional

Published
2021
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13. Initial Characterization of Active Transitioning Centaur, P/2019 LD2 (ATLAS), Using Hubble, Spitzer, ZTF, Keck, Apache Point Observatory, and GROWTH Visible and Infrared Imaging and Spectroscopy

Author

Bolin, Bryce T., primary, Fernandez, Yanga R., additional, Lisse, Carey M., additional, Holt, Timothy R., additional, Lin, Zhong-Yi, additional, Purdum, Josiah N., additional, Deshmukh, Kunal P., additional, Bauer, James M., additional, Bellm, Eric C., additional, Bodewits, Dennis, additional, Burdge, Kevin B., additional, Carey, Sean J., additional, Copperwheat, Chris M., additional, Helou, George, additional, Ho, Anna Y. Q., additional, Horner, Jonathan, additional, Roestel, Jan van, additional, Bhalerao, Varun, additional, Chang, Chan-Kao, additional, Chen, Christine, additional, Hsu, Chen-Yen, additional, Ip, Wing-Huen, additional, Kasliwal, Mansi M., additional, Masci, Frank J., additional, Ngeow, Chow-Choong, additional, Quimby, Robert, additional, Burruss, Rick, additional, Coughlin, Michael, additional, Dekany, Richard, additional, Delacroix, Alexandre, additional, Drake, Andrew, additional, Duev, Dmitry A., additional, Graham, Matthew, additional, Hale, David, additional, Kupfer, Thomas, additional, Laher, Russ R., additional, Mahabal, Ashish, additional, Mróz, Przemyslaw J., additional, Neill, James D., additional, Riddle, Reed, additional, Rodriguez, Hector, additional, Smith, Roger M., additional, Soumagnac, Maayane T., additional, Walters, Richard, additional, Yan, Lin, additional, and Zolkower, Jeffry, additional

Published
2021
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14. Characterization of Temporarily Captured Minimoon 2020 CD3by Keck Time-resolved Spectrophotometry

Author

Bolin, Bryce T., primary, Fremling, Christoffer, additional, Holt, Timothy R., additional, Hankins, Matthew J., additional, Ahumada, Tomás, additional, Anand, Shreya, additional, Bhalerao, Varun, additional, Burdge, Kevin B., additional, Copperwheat, Chris M., additional, Coughlin, Michael, additional, Deshmukh, Kunal P., additional, De, Kishalay, additional, Kasliwal, Mansi M., additional, Morbidelli, Alessandro, additional, Purdum, Josiah N., additional, Quimby, Robert, additional, Bodewits, Dennis, additional, Chang, Chan-Kao, additional, Ip, Wing-Huen, additional, Hsu, Chen-Yen, additional, Laher, Russ R., additional, Lin, Zhong-Yi, additional, Lisse, Carey M., additional, Masci, Frank J., additional, Ngeow, Chow-Choong, additional, Tan, Hanjie, additional, Zhai, Chengxing, additional, Burruss, Rick, additional, Dekany, Richard, additional, Delacroix, Alexandre, additional, Duev, Dmitry A., additional, Graham, Matthew, additional, Hale, David, additional, Kulkarni, Shrinivas R., additional, Kupfer, Thomas, additional, Mahabal, Ashish, additional, Mróz, Przemyslaw J., additional, Neill, James D., additional, Riddle, Reed, additional, Rodriguez, Hector, additional, Smith, Roger M., additional, Soumagnac, Maayane T., additional, Walters, Richard, additional, Yan, Lin, additional, and Zolkower, Jeffry, additional

Published
2020
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15. Characterization of the Nucleus, Morphology, and Activity of Interstellar Comet 2I/Borisov by Optical and Near-infrared GROWTH, Apache Point, IRTF, ZTF, and Keck Observations

Author

Bolin, Bryce T., primary, Lisse, Carey M., additional, Kasliwal, Mansi M., additional, Quimby, Robert, additional, Tan, Hanjie, additional, Copperwheat, Chris M., additional, Lin, Zhong-Yi, additional, Morbidelli, Alessandro, additional, Abe, Lyu, additional, Bendjoya, Philippe, additional, Burdge, Kevin B., additional, Coughlin, Michael, additional, Fremling, Christoffer, additional, Itoh, Ryosuke, additional, Koss, Michael, additional, Masci, Frank J., additional, Maeno, Syota, additional, Mamajek, Eric E., additional, Marocco, Federico, additional, Murata, Katsuhiro, additional, Rivet, Jean-Pierre, additional, Sitko, Michael L., additional, Stern, Daniel, additional, Vernet, David, additional, Walters, Richard, additional, Yan, Lin, additional, Andreoni, Igor, additional, Bhalerao, Varun, additional, Bodewits, Dennis, additional, De, Kishalay, additional, Deshmukh, Kunal P., additional, Bellm, Eric C., additional, Blagorodnova, Nadejda, additional, Buzasi, Derek, additional, Cenko, S. Bradley, additional, Chang, Chan-Kao, additional, Chojnowski, Drew, additional, Dekany, Richard, additional, Duev, Dmitry A., additional, Graham, Matthew, additional, Jurić, Mario, additional, Kulkarni, Shrinivas R., additional, Kupfer, Thomas, additional, Mahabal, Ashish, additional, Neill, James D., additional, Ngeow, Chow-Choong, additional, Penprase, Bryan, additional, Riddle, Reed, additional, Rodriguez, Hector, additional, Smith, Roger M., additional, Rosnet, Philippe, additional, Sollerman, Jesper, additional, and Soumagnac, Maayane T., additional

Published
2020
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17. Characterization of the Nucleus, Morphology, and Activity of Interstellar Comet 2I/Borisov by Optical and Near-infrared GROWTH, Apache Point, IRTF, ZTF, and Keck Observations

Author

Bolin, Bryce T., Lisse, Carey M., Kasliwal, Mansi M., Quimby, Robert, Tan, Hanjie, Copperwheat, Chris M., Lin, Zhong-Yi, Morbidelli, Alessandro, Abe, Lyu, Bendjoya, Philippe, Burdge, Kevin B., Coughlin, Michael, Fremling, Christoffer, Itoh, Ryosuke, Koss, Michael, Masci, Frank J., Maeno, Syota, Mamajek, Eric E., Marocco, Federico, Murata, Katsuhiro, Rivet, Jean-Pierre, Sitko, Michael L., Stern, Daniel, Vernet, David, Walters, Richard, Yan, Lin, Andreoni, Igor, Bhalerao, Varun, Bodewits, Dennis, De, Kishalay, Deshmukh, Kunal P., Bellm, Eric C., Blagorodnova, Nadejda, Buzasi, Derek, Cenko, S. Bradley, Chang, Chan-Kao, Chojnowski, Drew, Dekany, Richard, Duev, Dmitry A., Graham, Matthew, Juric, Mario, Kulkarni, Shrinivas R., Kupfer, Thomas, Mahabal, Ashish, Neill, James D., Ngeow, Chow-Choong, Penprase, Bryan, Riddle, Reed, Rodriguez, Hector, Smith, Roger M., Rosnet, Philippe, Sollerman, Jesper, Soumagnac, Maayane T., Bolin, Bryce T., Lisse, Carey M., Kasliwal, Mansi M., Quimby, Robert, Tan, Hanjie, Copperwheat, Chris M., Lin, Zhong-Yi, Morbidelli, Alessandro, Abe, Lyu, Bendjoya, Philippe, Burdge, Kevin B., Coughlin, Michael, Fremling, Christoffer, Itoh, Ryosuke, Koss, Michael, Masci, Frank J., Maeno, Syota, Mamajek, Eric E., Marocco, Federico, Murata, Katsuhiro, Rivet, Jean-Pierre, Sitko, Michael L., Stern, Daniel, Vernet, David, Walters, Richard, Yan, Lin, Andreoni, Igor, Bhalerao, Varun, Bodewits, Dennis, De, Kishalay, Deshmukh, Kunal P., Bellm, Eric C., Blagorodnova, Nadejda, Buzasi, Derek, Cenko, S. Bradley, Chang, Chan-Kao, Chojnowski, Drew, Dekany, Richard, Duev, Dmitry A., Graham, Matthew, Juric, Mario, Kulkarni, Shrinivas R., Kupfer, Thomas, Mahabal, Ashish, Neill, James D., Ngeow, Chow-Choong, Penprase, Bryan, Riddle, Reed, Rodriguez, Hector, Smith, Roger M., Rosnet, Philippe, Sollerman, Jesper, and Soumagnac, Maayane T.

Abstract

We present visible and near-infrared (NIR) photometric and spectroscopic observations of interstellar object (ISO) 2I/Borisov taken from 2019 September 10 to 2019 December 20 using the GROWTH, the Apache Point Observatory Astrophysical Research Consortium 3.5 m, and the NASA Infrared Telescope Facility 3.0 m combined with pre- and postdiscovery observations of 2I obtained by the Zwicky Transient Facility from 2019 March 17 to 2019 May 5. Comparison with imaging of distant solar system comets shows an object very similar to mildly active solar system comets with an outgassing rate of similar to 10(27)mol s(-1). The photometry, taken in filters spanning the visible and NIR range, shows a gradual brightening trend of similar to 0.03 mag day(-1)since 2019 September 10 UTC for a reddish object becoming neutral in the NIR. The light curve from recent and prediscovery data reveals a brightness trend suggesting the recent onset of significant H2O sublimation with the comet being active with super volatiles such as CO at heliocentric distances >6 au consistent with its extended morphology. Using the advanced capability to significantly reduce the scattered light from the coma enabled by high-resolution NIR images from Keck adaptive optics taken on 2019 October 4, we estimate a diameter for 2I's nucleus of less than or similar to 1.4 km. We use the size estimates of 1I/'Oumuamua and 2I/Borisov to roughly estimate the slope of the ISO size distribution, resulting in a slope of similar to 3.4 1.2, similar to solar system comets and bodies produced from collisional equilibrium.

Published
2020
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18. Initial Characterization of Active Transitioning Centaur, P/2019 LD2 (ATLAS), Using Hubble, Spitzer, ZTF, Keck, Apache Point Observatory, and GROWTH Visible and Infrared Imaging and Spectroscopy.

Author

Bolin, Bryce T., Fernandez, Yanga R., Lisse, Carey M., Holt, Timothy R., Lin, Zhong-Yi, Purdum, Josiah N., Deshmukh, Kunal P., Bauer, James M., Bellm, Eric C., Bodewits, Dennis, Burdge, Kevin B., Carey, Sean J., Copperwheat, Chris M., Helou, George, Ho, Anna Y. Q., Horner, Jonathan, van Roestel, Jan, Bhalerao, Varun, Chang, Chan-Kao, and Chen, Christine

Published
2021
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19. Characterization of Temporarily Captured Minimoon 2020 CD3 by Keck Time-resolved Spectrophotometry.

Author

Bolin, Bryce T., Fremling, Christoffer, Holt, Timothy R., Hankins, Matthew J., Ahumada, Tomás, Anand, Shreya, Bhalerao, Varun, Burdge, Kevin B., Copperwheat, Chris M., Coughlin, Michael, Deshmukh, Kunal P., De, Kishalay, Kasliwal, Mansi M., Morbidelli, Alessandro, Purdum, Josiah N., Quimby, Robert, Bodewits, Dennis, Chang, Chan-Kao, Ip, Wing-Huen, and Hsu, Chen-Yen

Published
2020
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20. The first post-Kepler brightness dips of KIC 8462852

Author

Boyajian, Tabetha. S., Alonso, Roi, Ammerman, Alex, Armstrong, David, Ramos, A. Asensio, Barkaoui, K., Beatty, Thomas G., Benkhaldoun, Z., Benni, Paul, O. Bentley, Rory, Berdyugin, Andrei, Berdyugina, Svetlana, Bergeron, Serge, Bieryla, Allyson, Blain, Michaela G., Blanco, Alicia Capetillo, Bodman, Eva H. L., Boucher, Anne, Bradley, Mark, Brincat, Stephen M., Brink, Thomas G., Briol, John, Brown, David J. A., Budaj, J., Burdanov, A., Cale, B., Carbo, Miguel Aznar, García, R. Castillo, Clark, Wendy J, Clayton, Geoffrey C., Clem, James L., Coker, Phillip H, Cook, Evan M., Copperwheat, Chris M., Curtis, J. L., Cutri, R. M., Cseh, B., Cynamon, C. H., Daniels, Alex J., Davenport, James R. A., Deeg, Hans J., Lorenzo, Roberto De, Jaeger, Thomas De, Desrosiers, Jean-bruno, Dolan, John, Dowhos, D. J., Dubois, Franky, Durkee, R., Dvorak, Shawn, Easley, Lynn, Edwards, N., Ellis, Tyler G., Erdelyi, Emery, Ertel, Steve, Farfán, Rafael. G., Farihi, J., Filippenko, Alexei V., Foxell, Emma, Gandolfi, Davide, Garcia, Faustino, Giddens, F., Gillon, M., González-carballo, Juan-luis, González-fernández, C., Hernández, J. I. González, Graham, Keith A., Greene, Kenton A., Gregorio, J., Hallakoun, Na’ama, Hanyecz, Ottó, Harp, G. R., Henry, Gregory W., Herrero, E., Hildbold, Caleb F., Hinzel, D., Holgado, G., Ignácz, Bernadett, Ilyin, Ilya, Ivanov, Valentin D., Jehin, E., Jermak, Helen E., Johnston, Steve, Kafka, S., Kalup, Csilla, Kardasis, Emmanuel, Kaspi, Shai, Kennedy, Grant M., Kiefer, F., Kielty, C. L., Kessler, Dennis, Kiiskinen, H., Killestein, T. L., King, Ronald A., Kollar, V., Korhonen, H., Kotnik, C., Könyves-tóth, Réka, Kriskovics, Levente, Krumm, Nathan, Krushinsky, Vadim, Kundra, E., Lachapelle, Francois-rene, Lacourse, D., Lake, P., Lam, Kristine, Lamb, Gavin P., Lane, Dave, Lau, Marie Wingyee, Lewin, Pablo, Lintott, Chris, Lisse, Carey, Logie, Ludwig, Longeard, Nicolas, Villanueva, M. Lopez, Ludington, E. Whit, Mainzer, A., Malo, Lison, Maloney, Chris, Mann, A., Mantero, A., Marengo, Massimo, Marchant, Jon, Martínez González, M. J., Masiero, Joseph R., Mauerhan, Jon C., Mccormac, James, Mcneely, Aaron, Meng, Huan Y. A., Miller, Mike, Molnar, Lawrence A., Morales, J. C., Morris, Brett M., Muterspaugh, Matthew W., Nespral, David, Nugent, C. R., Nugent, Katherine M., Odasso, A., O’keeffe, Derek, Oksanen, A., O’meara, John M., Ordasi, András, Osborn, Hugh, Ott, John J., Parks, J. R., Perez, Diego Rodriguez, Petriew, Vance, Pickard, R, Pál, András, Plavchan, P., Pollacco, Don, Nuñez, F. Pozo, J. Pozuelos, F., Rau, Steve, Redfield, Seth, Relles, Howard, Ribas, Ignasi, Richards, Jon, Saario, Joonas L. O., Safron, Emily J., Sallai, J. Martin, Sárneczky, Krisztián, Schaefer, Bradley E., Schumer, Clea F., Schwartzendruber, Madison, Siegel, Michael H., Siemion, Andrew P. V., Simmons, Brooke D., Simon, Joshua D., Simón-díaz, S., Sitko, Michael L., Socas-navarro, Hector, Sódor, Á., Starkey, Donn, Steele, Iain A., Stone, Geoff, Strassmeier, Klaus G., Street, R. A., Sullivan, Tricia, Suomela, J., Swift, J. J., Szabó, Gyula M., Szabó, Róbert, Szakáts, Róbert, Szalai, Tamás, Tanner, Angelle M., Toledo-padrón, B., Tordai, Tamás, Triaud, Amaury H. M. J., Turner, Jake D., Ulowetz, Joseph H., Urbanik, Marian, Vanaverbeke, Siegfried, Vanderburg, Andrew, Vida, Krisztián, Vietje, Brad P., Vinkó, József, Braun, K. Von, Waagen, Elizabeth O., Walsh, Dan, Watson, Christopher A., Weir, R. C., Wenzel, Klaus, Plaza, C. Westendorp, Williamson, Michael W., Wright, Jason T., Wyatt, M. C., Zheng, Weikang, Zsidi, Gabriella, Boyajian, Tabetha. S., Alonso, Roi, Ammerman, Alex, Armstrong, David, Ramos, A. Asensio, Barkaoui, K., Beatty, Thomas G., Benkhaldoun, Z., Benni, Paul, O. Bentley, Rory, Berdyugin, Andrei, Berdyugina, Svetlana, Bergeron, Serge, Bieryla, Allyson, Blain, Michaela G., Blanco, Alicia Capetillo, Bodman, Eva H. L., Boucher, Anne, Bradley, Mark, Brincat, Stephen M., Brink, Thomas G., Briol, John, Brown, David J. A., Budaj, J., Burdanov, A., Cale, B., Carbo, Miguel Aznar, García, R. Castillo, Clark, Wendy J, Clayton, Geoffrey C., Clem, James L., Coker, Phillip H, Cook, Evan M., Copperwheat, Chris M., Curtis, J. L., Cutri, R. M., Cseh, B., Cynamon, C. H., Daniels, Alex J., Davenport, James R. A., Deeg, Hans J., Lorenzo, Roberto De, Jaeger, Thomas De, Desrosiers, Jean-bruno, Dolan, John, Dowhos, D. J., Dubois, Franky, Durkee, R., Dvorak, Shawn, Easley, Lynn, Edwards, N., Ellis, Tyler G., Erdelyi, Emery, Ertel, Steve, Farfán, Rafael. G., Farihi, J., Filippenko, Alexei V., Foxell, Emma, Gandolfi, Davide, Garcia, Faustino, Giddens, F., Gillon, M., González-carballo, Juan-luis, González-fernández, C., Hernández, J. I. González, Graham, Keith A., Greene, Kenton A., Gregorio, J., Hallakoun, Na’ama, Hanyecz, Ottó, Harp, G. R., Henry, Gregory W., Herrero, E., Hildbold, Caleb F., Hinzel, D., Holgado, G., Ignácz, Bernadett, Ilyin, Ilya, Ivanov, Valentin D., Jehin, E., Jermak, Helen E., Johnston, Steve, Kafka, S., Kalup, Csilla, Kardasis, Emmanuel, Kaspi, Shai, Kennedy, Grant M., Kiefer, F., Kielty, C. L., Kessler, Dennis, Kiiskinen, H., Killestein, T. L., King, Ronald A., Kollar, V., Korhonen, H., Kotnik, C., Könyves-tóth, Réka, Kriskovics, Levente, Krumm, Nathan, Krushinsky, Vadim, Kundra, E., Lachapelle, Francois-rene, Lacourse, D., Lake, P., Lam, Kristine, Lamb, Gavin P., Lane, Dave, Lau, Marie Wingyee, Lewin, Pablo, Lintott, Chris, Lisse, Carey, Logie, Ludwig, Longeard, Nicolas, Villanueva, M. Lopez, Ludington, E. Whit, Mainzer, A., Malo, Lison, Maloney, Chris, Mann, A., Mantero, A., Marengo, Massimo, Marchant, Jon, Martínez González, M. J., Masiero, Joseph R., Mauerhan, Jon C., Mccormac, James, Mcneely, Aaron, Meng, Huan Y. A., Miller, Mike, Molnar, Lawrence A., Morales, J. C., Morris, Brett M., Muterspaugh, Matthew W., Nespral, David, Nugent, C. R., Nugent, Katherine M., Odasso, A., O’keeffe, Derek, Oksanen, A., O’meara, John M., Ordasi, András, Osborn, Hugh, Ott, John J., Parks, J. R., Perez, Diego Rodriguez, Petriew, Vance, Pickard, R, Pál, András, Plavchan, P., Pollacco, Don, Nuñez, F. Pozo, J. Pozuelos, F., Rau, Steve, Redfield, Seth, Relles, Howard, Ribas, Ignasi, Richards, Jon, Saario, Joonas L. O., Safron, Emily J., Sallai, J. Martin, Sárneczky, Krisztián, Schaefer, Bradley E., Schumer, Clea F., Schwartzendruber, Madison, Siegel, Michael H., Siemion, Andrew P. V., Simmons, Brooke D., Simon, Joshua D., Simón-díaz, S., Sitko, Michael L., Socas-navarro, Hector, Sódor, Á., Starkey, Donn, Steele, Iain A., Stone, Geoff, Strassmeier, Klaus G., Street, R. A., Sullivan, Tricia, Suomela, J., Swift, J. J., Szabó, Gyula M., Szabó, Róbert, Szakáts, Róbert, Szalai, Tamás, Tanner, Angelle M., Toledo-padrón, B., Tordai, Tamás, Triaud, Amaury H. M. J., Turner, Jake D., Ulowetz, Joseph H., Urbanik, Marian, Vanaverbeke, Siegfried, Vanderburg, Andrew, Vida, Krisztián, Vietje, Brad P., Vinkó, József, Braun, K. Von, Waagen, Elizabeth O., Walsh, Dan, Watson, Christopher A., Weir, R. C., Wenzel, Klaus, Plaza, C. Westendorp, Williamson, Michael W., Wright, Jason T., Wyatt, M. C., Zheng, Weikang, and Zsidi, Gabriella

Published
2018

21. The First Post- Kepler Brightness Dips of KIC 8462852

Author

Boyajian, Tabetha. S., primary, Alonso, Roi, additional, Ammerman, Alex, additional, Armstrong, David, additional, Ramos, A. Asensio, additional, Barkaoui, K., additional, Beatty, Thomas G., additional, Benkhaldoun, Z., additional, Benni, Paul, additional, O. Bentley, Rory, additional, Berdyugin, Andrei, additional, Berdyugina, Svetlana, additional, Bergeron, Serge, additional, Bieryla, Allyson, additional, Blain, Michaela G., additional, Blanco, Alicia Capetillo, additional, Bodman, Eva H. L., additional, Boucher, Anne, additional, Bradley, Mark, additional, Brincat, Stephen M., additional, Brink, Thomas G., additional, Briol, John, additional, Brown, David J. A., additional, Budaj, J., additional, Burdanov, A., additional, Cale, B., additional, Carbo, Miguel Aznar, additional, García, R. Castillo, additional, Clark, Wendy J, additional, Clayton, Geoffrey C., additional, Clem, James L., additional, Coker, Phillip H, additional, Cook, Evan M., additional, Copperwheat, Chris M., additional, Curtis, J. L., additional, Cutri, R. M., additional, Cseh, B., additional, Cynamon, C. H., additional, Daniels, Alex J., additional, Davenport, James R. A., additional, Deeg, Hans J., additional, Lorenzo, Roberto De, additional, Jaeger, Thomas de, additional, Desrosiers, Jean-Bruno, additional, Dolan, John, additional, Dowhos, D. J., additional, Dubois, Franky, additional, Durkee, R., additional, Dvorak, Shawn, additional, Easley, Lynn, additional, Edwards, N., additional, Ellis, Tyler G., additional, Erdelyi, Emery, additional, Ertel, Steve, additional, Farfán, Rafael. G., additional, Farihi, J., additional, Filippenko, Alexei V., additional, Foxell, Emma, additional, Gandolfi, Davide, additional, Garcia, Faustino, additional, Giddens, F., additional, Gillon, M., additional, González-Carballo, Juan-Luis, additional, González-Fernández, C., additional, Hernández, J. I. González, additional, Graham, Keith A., additional, Greene, Kenton A., additional, Gregorio, J., additional, Hallakoun, Na’ama, additional, Hanyecz, Ottó, additional, Harp, G. R., additional, Henry, Gregory W., additional, Herrero, E., additional, Hildbold, Caleb F., additional, Hinzel, D., additional, Holgado, G., additional, Ignácz, Bernadett, additional, Ilyin, Ilya, additional, Ivanov, Valentin D., additional, Jehin, E., additional, Jermak, Helen E., additional, Johnston, Steve, additional, Kafka, S., additional, Kalup, Csilla, additional, Kardasis, Emmanuel, additional, Kaspi, Shai, additional, Kennedy, Grant M., additional, Kiefer, F., additional, Kielty, C. L., additional, Kessler, Dennis, additional, Kiiskinen, H., additional, Killestein, T. L., additional, King, Ronald A., additional, Kollar, V., additional, Korhonen, H., additional, Kotnik, C., additional, Könyves-Tóth, Réka, additional, Kriskovics, Levente, additional, Krumm, Nathan, additional, Krushinsky, Vadim, additional, Kundra, E., additional, Lachapelle, Francois-Rene, additional, LaCourse, D., additional, Lake, P., additional, Lam, Kristine, additional, Lamb, Gavin P., additional, Lane, Dave, additional, Lau, Marie Wingyee, additional, Lewin, Pablo, additional, Lintott, Chris, additional, Lisse, Carey, additional, Logie, Ludwig, additional, Longeard, Nicolas, additional, Villanueva, M. Lopez, additional, Ludington, E. Whit, additional, Mainzer, A., additional, Malo, Lison, additional, Maloney, Chris, additional, Mann, A., additional, Mantero, A., additional, Marengo, Massimo, additional, Marchant, Jon, additional, Martínez González, M. J., additional, Masiero, Joseph R., additional, Mauerhan, Jon C., additional, McCormac, James, additional, McNeely, Aaron, additional, Meng, Huan Y. A., additional, Miller, Mike, additional, Molnar, Lawrence A., additional, Morales, J. C., additional, Morris, Brett M., additional, Muterspaugh, Matthew W., additional, Nespral, David, additional, Nugent, C. R., additional, Nugent, Katherine M., additional, Odasso, A., additional, O’Keeffe, Derek, additional, Oksanen, A., additional, O’Meara, John M., additional, Ordasi, András, additional, Osborn, Hugh, additional, Ott, John J., additional, Parks, J. R., additional, Perez, Diego Rodriguez, additional, Petriew, Vance, additional, Pickard, R, additional, Pál, András, additional, Plavchan, P., additional, Pollacco, Don, additional, Nuñez, F. Pozo, additional, J. Pozuelos, F., additional, Rau, Steve, additional, Redfield, Seth, additional, Relles, Howard, additional, Ribas, Ignasi, additional, Richards, Jon, additional, Saario, Joonas L. O., additional, Safron, Emily J., additional, Sallai, J. Martin, additional, Sárneczky, Krisztián, additional, Schaefer, Bradley E., additional, Schumer, Clea F., additional, Schwartzendruber, Madison, additional, Siegel, Michael H., additional, Siemion, Andrew P. V., additional, Simmons, Brooke D., additional, Simon, Joshua D., additional, Simón-Díaz, S., additional, Sitko, Michael L., additional, Socas-Navarro, Hector, additional, Sódor, Á., additional, Starkey, Donn, additional, Steele, Iain A., additional, Stone, Geoff, additional, Strassmeier, Klaus G., additional, Street, R. A., additional, Sullivan, Tricia, additional, Suomela, J., additional, Swift, J. J., additional, Szabó, Gyula M., additional, Szabó, Róbert, additional, Szakáts, Róbert, additional, Szalai, Tamás, additional, Tanner, Angelle M., additional, Toledo-Padrón, B., additional, Tordai, Tamás, additional, Triaud, Amaury H. M. J., additional, Turner, Jake D., additional, Ulowetz, Joseph H., additional, Urbanik, Marian, additional, Vanaverbeke, Siegfried, additional, Vanderburg, Andrew, additional, Vida, Krisztián, additional, Vietje, Brad P., additional, Vinkó, József, additional, Braun, K. von, additional, Waagen, Elizabeth O., additional, Walsh, Dan, additional, Watson, Christopher A., additional, Weir, R. C., additional, Wenzel, Klaus, additional, Plaza, C. Westendorp, additional, Williamson, Michael W., additional, Wright, Jason T., additional, Wyatt, M. C., additional, Zheng, WeiKang, additional, and Zsidi, Gabriella, additional

Published
2018
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22. The New Robotic Telescope: progress report

Author

Marshall, Heather K., Spyromilio, Jason, Usuda, Tomonori, Jermak, Helen E., Barrera, Josué, Copley, David, Copperwheat, Chris M., De Cos Juez, Javier, Gracia Rodriquez, Javier, Fernandez-Valdivia, J. J., Garcí a Piñero, A., Gutiérrez, Carlos M., Harvey, Éamonn, Insausti, Maider, Knapen, Johan H., Maudes Gutiérrez, Antonio, McGrath, Adrian M., Oria, Asier, Ranjbar, Ali, Rebolo-López, Rafael, Steele, Iain A., Torres, Miguel, Xu, Dong, Panyaphirawat, Thirasak, and Aukkaravittayapun, Suparerk

Published
2020
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23. Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1

Author

Gillon, Michaël, primary, Triaud, Amaury H. M. J., additional, Demory, Brice-Olivier, additional, Jehin, Emmanuël, additional, Agol, Eric, additional, Deck, Katherine M., additional, Lederer, Susan M., additional, de Wit, Julien, additional, Burdanov, Artem, additional, Ingalls, James G., additional, Bolmont, Emeline, additional, Leconte, Jeremy, additional, Raymond, Sean N., additional, Selsis, Franck, additional, Turbet, Martin, additional, Barkaoui, Khalid, additional, Burgasser, Adam, additional, Burleigh, Matthew R., additional, Carey, Sean J., additional, Chaushev, Aleksander, additional, Copperwheat, Chris M., additional, Delrez, Laetitia, additional, Fernandes, Catarina S., additional, Holdsworth, Daniel L., additional, Kotze, Enrico J., additional, Van Grootel, Valérie, additional, Almleaky, Yaseen, additional, Benkhaldoun, Zouhair, additional, Magain, Pierre, additional, and Queloz, Didier, additional

Published
2017
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26. The AM Canum Venaticorum binary SDSS J173047.59+554518.5

Author

Carter, P. J., Steeghs, D., Marsh, Tom, Kupfer, T., Copperwheat, Chris M., Groot, Paul J., and Nelemans, Gijs

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics, QC, QB
Abstract

The AM Canum Venaticorum (AM CVn) binaries are a rare group of hydrogen-deficient, ultrashort period, mass-transferring white dwarf binaries and are possible progenitors of Type Ia supernovae. We present time-resolved spectroscopy of the recently discovered AM CVn binary SDSS J173047.59+554518.5. The average spectrum shows strong double-peaked helium emission lines, as well as a variety of metal lines, including neon; this is the second detection of neon in an AM CVn binary, after the much brighter system GP Com. We detect no calcium in the accretion disc, a puzzling feature that has been noted in many of the longer period AM CVn binaries. We measure an orbital period, from the radial velocities of the emission lines, of 35.2 ± 0.2 min, confirming the ultracompact binary nature of the system. The emission lines seen in SDSS J1730 are very narrow, although double-peaked, implying a low-inclination, face-on accretion disc; using the measured velocities of the line peaks, we estimate i ≤ 11°. This low inclination makes SDSS J1730 an excellent system for the identification of emission lines.

Published
2014

27. The planets around NN Serpentis : still there

Author

Marsh, Tom, Parsons, S. G., Bours, Madelon C. P., Littlefair, Stuart P., Copperwheat, Chris M., Dhillon, Vik S., Breedt, E., Caceres, Claudio, and Schreiber, M. R.

Subjects
Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, QC
Abstract

We present 25 new eclipse times of the white dwarf binary NN Ser taken with the high-speed camera ULTRACAM on the William Herschel Telescope and New Technology Telescope, the RISE camera on the Liverpool Telescope and HAWK-I on the Very Large Telescope to test the two-planet model proposed to explain variations in its eclipse times measured over the last 25 yr. The planetary model survives the test with flying colours, correctly predicting a progressive lag in eclipse times of 36 s that has set in since 2010 compared to the previous 8 yr of precise times. Allowing both orbits to be eccentric, we find orbital periods of 7.9 ± 0.5 and 15.3 ± 0.3 yr, and masses of 2.3 ± 0.5 and 7.3 ± 0.3 MJ. We also find dynamically long-lived orbits consistent with the data, associated with 2:1 and 5:2 period ratios. The data scatter by 0.07 s relative to the best-fitting model, by some margin the most precise of any of the proposed eclipsing compact object planet hosts. Despite the high precision, degeneracy in the orbit fits prevents a significant measurement of a period change of the binary and of N-body effects. Finally, we point out a major flaw with a previous dynamical stability analysis of NN Ser, and by extension, with a number of analyses of similar systems.

Published
2014

28. PG 1018-047: the longest period subdwarf B binary

Author

Deca, Jan, Marsh, Thomas R, Ostensen, Roy, Morales-Rueda, Luisa, Copperwheat, Chris M, Wade, Richard A, Stark, Michelle A, Maxted, Pierre FL, Nelemans, Gijs, and Heber, Uli

Subjects
close [binaries], subdwarfs, evolution [stars], PG 1018−047, spectroscopic [binaries], individual [stars]
Abstract

About 50 per cent of all known hot subdwarf B stars (sdBs) reside in close (short-period) binaries, for which common-envelope ejection is the most likely formation mechanism. However, Han et al. predict that the majority of sdBs should form through stable mass transfer leading to long-period binaries. Determining orbital periods for these systems is challenging and while the orbital periods of ∼100 short-period systems have been measured, there are no periods measured above 30 d. As part of a large programme to characterize the orbital periods of sdB binaries and their formation history, we have found that PG 1018−047 has an orbital period of 759.8 ± 5.8 d, easily making it the longest period ever detected for a sdB binary. Exploiting the Balmer lines of the subdwarf primary and the narrow absorption lines of the companion present in the spectra, we derive the radial velocity amplitudes of both stars, and estimate the mass ratio M_MS/M_sdB= 1.6 ± 0.2. From the combination of visual and infrared photometry, the spectral type of the companion star is determined to be mid-K. Submitted for publication in MNRAS, 12 pages, 6 figures, 8 tables ispartof: Monthly Notices of the Royal Astronomical Society vol:421 issue:4 pages:2798-2808 status: published

Published
2012

29. Discovery of ZZ cetis in detached white dwarf plus main-sequence binaries

Author

Pyrzas, S, Gansicke, B, Hermes, J. J., Copperwheat, Chris M., Rebassa-Mansergas, A, Dhillon, Vik S., Littlefair, Stuart P., Marsh, Tom R., Parsons, Steven G., Bento (Da Silva Bento), Joao, Pyrzas, S, Gansicke, B, Hermes, J. J., Copperwheat, Chris M., Rebassa-Mansergas, A, Dhillon, Vik S., Littlefair, Stuart P., Marsh, Tom R., Parsons, Steven G., and Bento (Da Silva Bento), Joao

Abstract

We present the first results of a dedicated search for pulsating white dwarfs (WDs) in detached WD plus main-sequence (MS) binaries. Candidate systems were selected from a catalogue of WD+MS binaries, based on the surface gravities and effective temperatures of the WDs. We observed a total of 26 systems using ULTRACAM mounted on ESO's 3.5 m New Technology Telescope at La Silla. Our photometric observations reveal pulsations in seven WDs of our sample, including the first pulsating WD with an MS companion in a post-common envelope (CE) binary, SDSS J1136+0409. Asteroseismology of these new pulsating systems will provide crucial insight into how binary interactions, particularly the CE phase, affect the internal structure and evolution of WDs. In addition, our observations have revealed the partially eclipsing nature of one of our targets, SDSS J1223-0056

Published
2015

30. PHL 1445: An eclipsing cataclysmic variable with a substellar donor near the period minimum

Author

McAllister, M J, Tunnicliffe, Rachel L., Littlefair, Stuart P., Baraffe, I, Dhillon, Vik S., Marsh, T. R., Bento (Da Silva Bento), Joao, Bochinski, J, Bours, M. C. P., Breedt, E., Copperwheat, Chris M., McAllister, M J, Tunnicliffe, Rachel L., Littlefair, Stuart P., Baraffe, I, Dhillon, Vik S., Marsh, T. R., Bento (Da Silva Bento), Joao, Bochinski, J, Bours, M. C. P., Breedt, E., and Copperwheat, Chris M.

Abstract

We present high-speed, three-colour photometry of the eclipsing dwarf nova PHL 1445, which, with an orbital period of 76.3 min, lies just below the period minimum of ∼82 min for cataclysmic variable stars (CVs). Averaging four eclipses reveals resolved eclipses of the white dwarf and bright spot. We determined the system parameters by fitting a parametrized eclipse model to the averaged light curve. We obtain a mass ratio of q = 0.087 ± 0.006 and inclination i = 85 ∘. 2 ± 0 ∘. 9. The primary and donor masses were found to be Mw = 0.73 ± 0.03 M⊙ and Md = 0.064 ± 0.005 M⊙, respectively. Through multicolour photometry a temperature of the white dwarf of Tw = 13 200 ± 700 K and a distance of 220 ± 50 pc were determined. The evolutionary state of PHL 1445 is uncertain. We are able to rule out a significantly evolved donor, but not one that is slightly evolved. Formation with a brown dwarf donor is plausible, though the brown dwarf would need to be no older than 600 Myr at the start of mass transfer, requiring an extremely low mass ratio (q = 0.025) progenitor system. PHL 1445 joins SDSS 1433 as a sub-period minimum CV with a substellar donor. The existence of two such systems raises an alternative possibility that current estimates for the intrinsic scatter and/or position of the period minimum may be in error.

Published
2015

31. Optical transmission photometry of the highly inflated exoplanet WASP-17b

Author

Bento (Da Silva Bento), Joao, Wheatley, P J, Copperwheat, Chris M., Fortney, Jonathon, Dhillon, Vik S., Hickman, R, Littlefair, Stuart P., Marsh, T. R., Parsons, Steven G., Southworth, J, Bento (Da Silva Bento), Joao, Wheatley, P J, Copperwheat, Chris M., Fortney, Jonathon, Dhillon, Vik S., Hickman, R, Littlefair, Stuart P., Marsh, T. R., Parsons, Steven G., and Southworth, J

Abstract

We present ground-based high-precision observations of the transit of WASP-17b using the multiband photometer ULTRACAM on ESO's New Technology Telescope (NTT) in the context of performing transmission spectrophotometry of this highly inflated exoplanet. Our choice of filters (SDSS u′, g′ and r′ bands) is designed to probe for the presence of opacity sources in the upper atmosphere. We find evidence for a wavelength dependence in the planet radius in the form of enhanced absorption in the SDSS r′ band, consistent with a previously detected broad sodium feature. We present a new independent measurement of the planetary radius at Rpl = 1.97 ± 0.06RJ, which confirms this planet as the most inflated exoplanet known to date. Our measurements are most consistent with an atmospheric profile devoid of enhanced TiO opacity, previously predicted to be present for this planet.

Published
2014

32. Transmission photometry of WASP-12b: Simultaneous measurement of the planetary radius in three bands

Author

Copperwheat, Chris M., Wheatley, P. J., Southworth, J, Bento (Da Silva Bento), Joao, Marsh, T. R., Dhillon, Vik S., Fortney, Jonathon, Littlefair, Stuart P., Hickman, R, Copperwheat, Chris M., Wheatley, P. J., Southworth, J, Bento (Da Silva Bento), Joao, Marsh, T. R., Dhillon, Vik S., Fortney, Jonathon, Littlefair, Stuart P., and Hickman, R

Abstract

Transmission spectroscopy has been successfully used from both the ground and in space to characterize the atmospheres of transiting exoplanets. This technique is challenging from the ground because ground-based spectrographs tend not to be designed to be photometrically stable, and effects such as variable slit losses cause significant systematic uncertainties. An alternative approach is to use simultaneous photometric observations in multiple wavebands to determine wavelength-dependent transit depth differences. We report an application of this technique to one of the hottest known exoplanets, WASP-12b, using the triple-beam camera ULTRACAM. We obtained simultaneous light curves in Sloan u, and two narrow-band filters centred on 4169 and 6010 Å, with full widths at half-maximum 52 and 118 Å, respectively. We fit these light curves with a photometric model and determine the planetary radius in the three different bands. Our data show no evidence for a difference in planetary radius over the wavelength range we study, and are consistent with an atmosphere that is dominated by Rayleigh scattering from a high-altitude haze, as well as more complicated atmosphere models which include the effects of molecules such as TiO. Our planetary radius measurements have an average precision of 2.6 per cent, compared to the ̃1.4-2.4 per cent radius differences predicted by the models over this wavelength range. We also find a consistent time of ingress and egress across our three wavebands, in contrast to the early ingress which has been reported for this system at shorter wavelengths

Published
2013

33. An accurate mass and radius measurement for an ultracool white dwarf

Author

Parsons, Steven G., Gansicke, B, Marsh, Tom R., Bergeron, P, Copperwheat, Chris M., Dhillon, Vik S., Bento (Da Silva Bento), Joao, Littlefair, Stuart P., Schreiber, Matthias R, Parsons, Steven G., Gansicke, B, Marsh, Tom R., Bergeron, P, Copperwheat, Chris M., Dhillon, Vik S., Bento (Da Silva Bento), Joao, Littlefair, Stuart P., and Schreiber, Matthias R

Abstract

Studies of cool white dwarfs in the solar neighbourhood have placed a limit on the age of the Galactic disc of 8-9 billion years. However, determining their cooling ages requires the knowledge of their effective temperatures, masses, radii and atmospheric composition. So far, these parameters could only be inferred for a small number of ultracool white dwarfs for which an accurate distance is known, by fitting their spectral energy distributions in conjunction with a theoretical mass-radius relation. However, themass-radius relation remains largely untested, and the derived cooling ages are hence model dependent. Here we report direct measurements of the mass and radius of an ultracool white dwarf in the double-lined eclipsing binary SDSS J013851.54-001621.6. We find M WD = 0.529 ± 0.010M⊙ and R WD = 0.0131 ± 0.0003 R⊙. Our measurements are consistent with the mass-radius relation and we determine a robust cooling age of 9.5 billion years for the 3570K white dwarf. We find that the mass and radius of the low-mass companion star, M sec = 0.132 ± 0.003M⊙ and R sec = 0.165 ± 0.001 R⊙, are in agreement with evolutionarymodels. We also find evidence that this > 9.5Gyr old M5 star is still active, far beyond the activity lifetime for a star of its spectral type. This is likely caused by the high tidally enforced rotation rate of the star. The companion star is close to filling its Roche lobe and the system will evolve into a cataclysmic variable in only 70 Myr. Our direct measurements demonstrate that this system can be used to calibrate ultracool white dwarf atmospheric models

Published
2012

34. PROPERTIES OF AN ECLIPSING DOUBLE WHITE DWARF BINARY NLTT 11748

Author

Kaplan, David L., primary, Marsh, Thomas R., additional, Walker, Arielle N., additional, Bildsten, Lars, additional, Bours, Madelon C. P., additional, Breedt, Elmé, additional, Copperwheat, Chris M., additional, Dhillon, Vik S., additional, Howell, Steve B., additional, Littlefair, Stuart P., additional, Shporer, Avi, additional, and Steinfadt, Justin D. R., additional

Published
2013
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35. The Planets around the post-Common Envelope Binary NN Serpentis

Author

Hessman, Frederic V., primary, Beuermann, Klaus, additional, Dreizler, Stefan, additional, Marsh, Tom R., additional, Parsons, Steven G., additional, Copperwheat, Chris M., additional, Winget, Don E., additional, Miller, George F., additional, Hermes, James J., additional, Schreiber, Matthias R., additional, Kley, Wilhelm, additional, Dhillon, Vik S., additional, and Littlefair, Stuart P., additional

Published
2011
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36. The Planets around the post-Common Envelope Binary NN Serpentis.

Author

Hessman, Frederic V., Beuermann, Klaus, Dreizler, Stefan, Marsh, Tom R., Parsons, Steven G., Copperwheat, Chris M., Winget, Don E., Miller, George F., Hermes, James J., Schreiber, Matthias R., Kley, Wilhelm, Dhillon, Vik S., and Littlefair, Stuart P.

Subjects
ECLIPSING binaries, PLANETARY orbits, WHITE dwarf stars, CATACLYSMIC variable stars, STAR formation, STELLAR evolution, EVOLUTIONARY theories
Abstract

We have detected 2 circumbinary planets around the close binary system NN Serpentis using the orbital time delay effect measured via the sharp eclipses of the white dwarf primary. The present pre-cataclysmic binary was formed when the original ∼2 M⊙ primary expanded into a red giant, causing the secondary star to drop from its original orbit at a separation of about 1.4 A.U. down to its current separation at 0.0043 A.U. A quasi-adiabatic evolution of the circumbinary planets' orbits during the common-envelope phase would have placed them in unstable configurations, suggesting that they may have suffered significant orbital drag effects and were originally in much larger orbits. Alternatively, they may have been created as 2nd-generation planets during the last million years from the substantial amount of material lost during the creation of the binary, making them the youngest planets known. Either solution shows how little we actually understand about planetary formation. [ABSTRACT FROM AUTHOR]

Published
2011
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37. PROPERTIES OF AN ECLIPSING DOUBLE WHITE DWARF BINARY NLTT 11748.

Author

Kaplan, David L., Marsh, Thomas R., Walker, Arielle N., Bildsten, Lars, Bours, Madelon C. P., Breedt, Elmé, Copperwheat, Chris M., Dhillon, Vik S., Howell, Steve B., Littlefair, Stuart P., Shporer, Avi, and Steinfadt, Justin D. R.

Subjects
WHITE dwarf stars, BINARY stars, ECLIPSES, STELLAR orbits, STELLAR mass
Abstract

We present high-quality ULTRACAM photometry of the eclipsing detached double white dwarf binary NLTT 11748. This system consists of a carbon/oxygen white dwarf and an extremely low mass (<0.2 M☼) helium-core white dwarf in a 5.6 hr orbit. To date, such extremely low-mass white dwarfs, which can have thin, stably burning outer layers, have been modeled via poorly constrained atmosphere and cooling calculations where uncertainties in the detailed structure can strongly influence the eventual fates of these systems when mass transfer begins. With precise (individual precision ≈1%), high-cadence (≈2 s), multicolor photometry of multiple primary and secondary eclipses spanning >1.5 yr, we constrain the masses and radii of both objects in the NLTT 11748 system to a statistical uncertainty of a few percent. However, we find that overall uncertainty in the thickness of the envelope of the secondary carbon/oxygen white dwarf leads to a larger (≈13%) systematic uncertainty in the primary He WD's mass. Over the full range of possible envelope thicknesses, we find that our primary mass (0.136-0.162 M☼) and surface gravity (log (g) = 6.32-6.38; radii are 0.0423-0.0433 R☼) constraints do not agree with previous spectroscopic determinations. We use precise eclipse timing to detect the Rømer delay at 7σ significance, providing an additional weak constraint on the masses and limiting the eccentricity to ecos ω = (– 4 ± 5) × 10–5. Finally, we use multicolor data to constrain the secondary's effective temperature (7600 ± 120 K) and cooling age (1.6-1.7 Gyr). [ABSTRACT FROM AUTHOR]

Published
2014
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