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4 results on '"Boyajian, TS"'

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

Author

Boyajian, TS, Alonso, R, Ammerman, A, Armstrong, D, Ramos, AA, Barkaoui, K, Beatty, TG, Benkhaldoun, Z, Benni, P, Bentley, RO, Berdyugin, A, Berdyugina, S, Bergeron, S, Bieryla, A, Blain, MG, Blanco, AC, Bodman, EHL, Boucher, A, Bradley, M, Brincat, SM, Brink, TG, Briol, J, Brown, DJA, Budaj, J, Burdanov, A, Cale, B, Carbo, MA, Garcia, RC, Clark, WJ, Clayton, GC, Clem, JL, Coker, PH, Cook, EM, Copperwheat, CM, Curtis, JL, Cutri, RM, Cseh, B, Cynamon, CH, Daniels, AJ, Davenport, JRA, Deeg, HJ, Lorenzo, RD, Jaeger, TD, Desrosiers, JB, Dolan, J, Dowhos, DJ, Dubois, F, Durkee, R, Dvorak, S, Easley, L, Edwards, N, Ellis, TG, Erdelyi, E, Ertel, S, Farfán, RG, Farihi, J, Filippenko, AV, Foxell, E, Gandolfi, D, Garcia, F, Giddens, F, Gillon, M, González-Carballo, JL, González-Fernández, C, Hernández, JIG, Graham, KA, Greene, KA, Gregorio, J, Hallakoun, N, Hanyecz, O, Harp, GR, Henry, GW, Herrero, E, Hildbold, CF, Hinzel, D, Holgado, G, Ignácz, B, Ilyin, I, Ivanov, VD, Jehin, E, Jermak, HE, Johnston, S, Kafka, S, Kalup, C, Kardasis, E, Kaspi, S, Kennedy, GM, Kiefer, F, Kielty, CL, Kessler, D, Kiiskinen, H, Killestein, TL, King, RA, Kollar, V, Korhonen, H, Kotnik, C, Könyves-Tóth, R, Kriskovics, L, Krumm, N, Krushinsky, V, Boyajian, TS [0000-0001-9879-9313], Clayton, GC [0000-0002-0141-7436], Davenport, JRA [0000-0002-0637-835X], Farihi, J [0000-0003-1748-602X], Hallakoun, N [0000-0002-0430-7793], Hanyecz, O [0000-0002-9415-5219], Kennedy, GM [0000-0001-6831-7547], Korhonen, H [0000-0003-0529-1161], Kriskovics, L [0000-0002-1792-546X], and Apollo - University of Cambridge Repository

Subjects
comets: general, stars: activity, stars: peculiar, stars: individual (KIC 8462852)
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 <

Published
2018

2. EVIDENCE for REFLECTED LIGHT from the MOST ECCENTRIC EXOPLANET KNOWN

Author

Kane, SR, Wittenmyer, RA ; https://orcid.org/0000-0001-9957-9304, Hinkel, NR, Roy, A, Mahadevan, S, Dragomir, D, Matthews, JM, Henry, GW, Chakraborty, A, Boyajian, TS, Wright, JT, Ciardi, DR, Fischer, DA, Butler, RP, Tinney, CG ; https://orcid.org/0000-0002-7595-0970, Carter, BD, Jones, HRA, Bailey, J ; https://orcid.org/0000-0002-5726-7000, O'Toole, SJ, Kane, SR, Wittenmyer, RA ; https://orcid.org/0000-0001-9957-9304, Hinkel, NR, Roy, A, Mahadevan, S, Dragomir, D, Matthews, JM, Henry, GW, Chakraborty, A, Boyajian, TS, Wright, JT, Ciardi, DR, Fischer, DA, Butler, RP, Tinney, CG ; https://orcid.org/0000-0002-7595-0970, Carter, BD, Jones, HRA, Bailey, J ; https://orcid.org/0000-0002-5726-7000, and O'Toole, SJ

Abstract

Planets in highly eccentric orbits form a class of objects not seen within our solar system. The most extreme case known among these objects is the planet orbiting HD 20782, with an orbital period of 597 days and an eccentricity of 0.96. Here we present new data and analysis for this system as part of the Transit Ephemeris Refinement and Monitoring Survey. We obtained CHIRON spectra to perform an independent estimation of the fundamental stellar parameters. New radial velocities from Anglo-Australian Telescope and PARAS observations during periastron passage greatly improve our knowledge of the eccentric nature of the orbit. The combined analysis of our Keplerian orbital and Hipparcos astrometry show that the inclination of the planetary orbit is , ruling out stellar masses for the companion. Our long-term robotic photometry show that the star is extremely stable over long timescales. Photometric monitoring of the star during predicted transit and periastron times using Microvariability and Oscillations of STars rule out a transit of the planet and reveal evidence of phase variations during periastron. These possible photometric phase variations may be caused by reflected light from the planet's atmosphere and the dramatic change in star-planet separation surrounding the periastron passage.

Published
2016

3. THREE TEMPERATE NEPTUNES ORBITING NEARBY STARS

Author

Fulton, BJ, Fulton, BJ, Howard, AW, Weiss, LM, Sinukoff, E, Petigura, EA, Isaacson, H, Hirsch, L, Marcy, GW, Henry, GW, Grunblatt, SK, Huber, D, Braun, KV, Boyajian, TS, Kane, SR, Wittrock, J, Horch, EP, Ciardi, DR, Howell, SB, Wright, JT, Ford, EB, Fulton, BJ, Fulton, BJ, Howard, AW, Weiss, LM, Sinukoff, E, Petigura, EA, Isaacson, H, Hirsch, L, Marcy, GW, Henry, GW, Grunblatt, SK, Huber, D, Braun, KV, Boyajian, TS, Kane, SR, Wittrock, J, Horch, EP, Ciardi, DR, Howell, SB, Wright, JT, and Ford, EB

Abstract

We present the discovery of three modestly irradiated, roughly Neptune-mass planets orbiting three nearby Solartype stars. HD 42618 b has a minimum mass of 15.4±2.4 M⊕, a semimajor axis of 0.55 au, an equilibrium temperature of 337 K, and is the first planet discovered to orbit the solar analogue host star, HD 42618. We also discover new planets orbiting the known exoplanet host stars HD 164922 and HD 143761 (p CrB). The new planet orbiting HD 164922 has a minimum mass of 12.9±1.6 M⊕ and orbits interior to the previously known Jovian mass planet orbiting at 2.1 au. HD 164922 c has a semimajor axis of 0.34 au and an equilibrium temperature of 418 K. HD 143761 c orbits with a semimajor axis of 0.44 au, has a minimum mass of 25±2 M⊕, and is the warmest of the three new planets with an equilibrium temperature of 445 K. It orbits exterior to the previously known warm Jupiter in the system. A transit search using space-based CoRoT data and ground-based photometry from the Automated Photometric Telescopes (APTs) at Fairborn Observatory failed to detect any transits, but the precise, high-cadence APT photometry helped to disentangle planetary-reflex motion from stellar activity. These planets were discovered as part of an ongoing radial velocity survey of bright, nearby, chromospherically inactive stars using the Automated Planet Finder (APF) telescope at Lick Observatory. The high-cadence APF data combined with nearly two decades of radial velocity data from Keck Observatory and gives unprecedented sensitivity to both short-period low-mass, and long-period intermediate-mass planets.

Published
2016

4. Planet Hunters IX. KIC 8462852 - Where's the flux?

Author

Boyajian, TS, LaCourse, DM, Rappaport, SA, Fabrycky, D, Fischer, DA, Gandolfi, D, Kennedy, GM, Korhonen, H, Liu, MC, Moor, A, Olah, K, Vida, K, Wyatt, MC, Best, WMJ, Brewer, J, Ciesla, F, Csák, B, Deeg, HJ, Dupuy, TJ, Handler, G, Heng, K, Howell, SB, Ishikawa, ST, Kovács, J, Kozakis, T, Kriskovics, L, Lehtinen, J, Lintott, C, Lynn, S, Nespral, D, Nikbakhsh, S, Schawinski, K, Schmitt, Smith, AM, Szabo, G, Szabo, R, Viuho, J, Wang, J, Weiksnar, A, Bosch, M, Connors, JL, Goodman, S, Green, G, Hoekstra, AJ, Jebson, T, Jek, KJ, Omohundro, MR, Schwengeler, HM, and Szewczyk, A

Subjects
planets and satellites: dynamical evolution and stability, 13. Climate action, comets: general, stars: activity, stars: individual: KIC 8462852, stars: peculiar
Abstract

Over the duration of the Kepler mission, KIC 8462852 was observed to undergo irregularly shaped, aperiodic dips in flux of up to ~20 per cent. The dipping activity can last for between 5 and 80 d.We characterize the object with high-resolution spectroscopy, spectral energy distribution fitting, radial velocity measurements, high-resolution imaging, and Fourier analyses of the Kepler light curve. We determine that KIC 8462852 is a typical main-sequence F3 V star that exhibits no significant IR excess, and has no very close interacting companions. In this paper, we describe various scenarios to explain the dipping events observed in the Kepler light curve.We confirm that the dipping signals in the data are not caused by any instrumental or data processing artefact, and thus are astrophysical in origin. We construct scenario-independent constraints on the size and location of a body in the system that are needed to reproduce the observations. We deliberate over several assorted stellar and circumstellar astrophysical scenarios, most of which have problems explaining the data in hand. By considering the observational constraints on dust clumps in orbit around a normal main-sequence star, we conclude that the scenario most consistent with the data in hand is the passage of a family of exocomet or planetesimal fragments, all of which are associated with a single previous break-up event, possibly caused by tidal disruption or thermal processing. The minimum total mass associated with these fragments likely exceeds 10-6 M⊕, corresponding to an original rocky body of >100 km in diameter. We discuss the necessity of future observations to help interpret the system.

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