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9 results on '"Kardasis, Emmanuel"'

1. The Rise and Fall of the King: The Correlation between FO Aquarii's Low States and the White Dwarf's Spindown

Author

Littlefield, Colin, Garnavich, Peter, Kennedy, Mark R., Patterson, Joseph, Kemp, Jonathan, Stiller, Robert A., Hambsch, Franz-Josef, Heras, Teofilo Arranz, Myers, Gordon, Stone, Geoffrey, Sjoberg, George, Dvorak, Shawn, Nelson, Peter, Popov, Velimir, Bonnardeau, Michel, Vanmunster, Tonny, de Miguel, Enrique, Alton, Kevin B., Harris, Barbara, Cook, Lewis M., Graham, Keith A., Brincat, Stephen M., Lane, David J., Foster, James, Pickard, Roger, Sabo, Richard, Vietje, Brad, Lemay, Damien, Briol, John, Krumm, Nathan, Dadighat, Michelle, Goff, William, Solomon, Rob, Padovan, Stefano, Bolt, Greg, Kardasis, Emmanuel, Debackere, Andre, Thrush, Jeff, Stein, William, Coulter, Daniel, Tsehmeystrenko, Valery, Gout, Jean-Francois, Lewin, Pablo, Galdies, Charles, Fernandez, David Cejudo, Walker, Gary, Boardman Jr., James, and Pellett, Emil

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

The intermediate polar FO Aquarii (FO Aqr) experienced its first-reported low-accretion states in 2016, 2017, and 2018, and using newly available photographic plates, we identify pre-discovery low states in 1965, 1966, and 1974. The primary focus of our analysis, however, is an extensive set of time-series photometry obtained between 2002 and 2018, with particularly intensive coverage of the 2016-2018 low states. After computing an updated spin ephemeris for the white dwarf (WD), we show that its spin period began to increase in 2014 after having spent 27 years decreasing; no other intermediate polar has experienced a sign change of its period derivative, but FO Aqr has now done so twice. Our central finding is that the recent low states all occurred shortly after the WD began to spin down, even though no low states were reported in the preceding quarter-century, when it was spinning up. Additionally, the system's mode of accretion is extremely sensitive to the mass-transfer rate, with accretion being almost exclusively disk-fed when FO Aqr is brighter than V~14 and substantially stream-fed when it is not. Even in the low states, a grazing eclipse remains detectable, confirming the presence of a disk-like structure (but not necessarily a Keplerian accretion disk). We relate these various observations to theoretical predictions that during the low state, the system's accretion disk dissipates into a non-Keplerian ring of diamagnetic blobs. Finally, a new XMM-Newton observation from a high state in 2017 reveals an anomalously soft X-ray spectrum and diminished X-ray luminosity compared to pre-2016 observations., Comment: Accepted for publication in ApJ

Published
2019
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2. 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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3. The need for Professional-Amateur collaborations in studies of Jupiter and Saturn

Author

Kardasis, Emmanuel, Rogers, John H., Orton, Glenn, Delcroix, Marc, Christou, Apostolos, Foulkes, Mike, Yanamandra-Fisher, Padma, Jacquesson, Michel, and Maravelias, Grigoris

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

The observation of gaseous giant planets is of high scientific interest. Although they have been the targets of several spacecraft missions, there still remains a need for continuous ground-based observations. As their atmospheres present fast dynamic environments on various time scales, the availability of time at professional telescopes is neither uniform nor of sufficient duration to assess temporal changes. However, numerous amateurs with small telescopes (of 15-40 cm) and modern hardware and software equipment can monitor these changes daily (within the 360-900nm range). Amateurs are able to trace the structure and the evolution of atmospheric features, such as major planetary-scale disturbances, vortices, and storms. Their observations provide a continuous record and it is not uncommon to trigger professional observations in cases of important events, such as sudden onset of global changes, storms and celestial impacts. For example, the continuous amateur monitoring has led to the discovery of fireballs in Jupiter's atmosphere, providing information not only on Jupiter's gravitational influence but also on the properties and populations of the impactors. Photometric monitoring of stellar occultations by the planets can reveal spatial/temporal variability in their atmospheric structure. Therefore, co-ordination and communication between professionals and amateurs is important. We present examples of such collaborations that: (i) engage systematic multi-wavelength observations and databases, (ii) examine the variability of cloud features over timescales from days to decades, (iii) provide, by ground-based professional and amateur observations, the necessary spatial and temporal resolution of features that will be studied by the interplanetary mission Juno, (iv) investigate video observations of Jupiter to identify impacts of small objects, (v) carry out stellar-occultation campaigns., Comment: 21 pages, 15 figures, accepted for publication in the Journal of the British Astronomical Association

Published
2015

4. First long-term study of the Venus' Cloud Discontinuity with uninterrupted observations

Author

Peralta, Javier, primary, Cidadão, António, additional, Morrone, Luigi, additional, Foster, Clyde, additional, Bullock, Mark, additional, Young, Eliot F., additional, Garate-Lopez, Itziar, additional, Sánchez-Lavega, Agustín, additional, Horinouchi, Takeshi, additional, Imamura, Takeshi, additional, Kardasis, Emmanuel, additional, Yamazaki, Atsushi, additional, and Watanabe, Shigeto, additional

Published
2023
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5. Amateur Observers Witness the Return of Venus’ Cloud Discontinuity

Author

Kardasis, Emmanuel (Manos), primary, Peralta, Javier, additional, Maravelias, Grigoris, additional, Imai, Masataka, additional, Wesley, Anthony, additional, Olivetti, Tiziano, additional, Naryzhniy, Yaroslav, additional, Morrone, Luigi, additional, Gallardo, Antonio, additional, Calapai, Giovanni, additional, Camarena, Joaquin, additional, Casquinha, Paulo, additional, Kananovich, Dzmitry, additional, MacNeill, Niall, additional, Viladrich, Christian, additional, and Takoudi, Alexia, additional

Published
2022
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6. The Rise and Fall of the King: The Correlation between FO Aquarii’s Low States and the White Dwarf’s Spin-down

Author

Littlefield, Colin, primary, Garnavich, Peter, additional, Kennedy, Mark R., additional, Patterson, Joseph, additional, Kemp, Jonathan, additional, Stiller, Robert A., additional, Hambsch, Franz-Josef, additional, Heras, Teófilo Arranz, additional, Myers, Gordon, additional, Stone, Geoffrey, additional, Sjöberg, George, additional, Dvorak, Shawn, additional, Nelson, Peter, additional, Popov, Velimir, additional, Bonnardeau, Michel, additional, Vanmunster, Tonny, additional, Miguel, Enrique de, additional, Alton, Kevin B., additional, Harris, Barbara, additional, Cook, Lewis M., additional, Graham, Keith A., additional, Brincat, Stephen M., additional, Lane, David J., additional, Foster, James, additional, Pickard, Roger, additional, Sabo, Richard, additional, Vietje, Brad, additional, Lemay, Damien, additional, Briol, John, additional, Krumm, Nathan, additional, Dadighat, Michelle, additional, Goff, William, additional, Solomon, Rob, additional, Padovan, Stefano, additional, Bolt, Greg, additional, Kardasis, Emmanuel, additional, Debackère, André, additional, Thrush, Jeff, additional, Stein, William, additional, Walter, Bradley, additional, Coulter, Daniel, additional, Tsehmeystrenko, Valery, additional, Gout, Jean-François, additional, Lewin, Pablo, additional, Galdies, Charles, additional, Fernandez, David Cejudo, additional, Walker, Gary, additional, Boardman, James, additional, and Pellett, Emil, additional

Published
2020
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7. 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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8. The need for professional-amateur collaboration in studies of Jupiter and Saturn.

Author

Kardasis, Emmanuel, Rogers, John H., Orton, Glenn, Delcroix, Marc, Christou, Apostolos, Foulkes, Mike, Yanamandra-Fisher, Padma, Jacquesson, Michel, and Maravelias, Grigoris

Subjects
*AMATEUR archaeologists, *JUPITER (Planet) research, *SATURN (Planet) research, *SPACE flight, *TELESCOPES, *ATMOSPHERIC structure, *COMPUTER software, *PLANETARY research, *ASTRONOMICAL observations
Abstract

The observation of the gaseous giant planets is of high scientific interest. Although they have been the targets of several spacecraft missions, there still remains a need for continuous ground-based observations. As their atmospheres present fast dynamic environments on varied timescales, the availability of time at professional telescopes is neither uniform nor of sufficient duration to assess temporal changes. On the other hand, numerous amateurs with small telescopes (with typical apertures of 15-40 cm) and modern hardware and software equipment can monitor these changes daily (within the 360-900nm wavelength range).Amateur observers are able to trace the structure and the evolution of atmospheric features, such as major planetary-scale disturbances, vortices, and storms.Their observations provide a continuous record and it is not uncommon to trigger professional observations in cases of important events, such as sudden onset of global changes, storms and celestial impacts. For example, the continuous amateur monitoring has led to the discovery of fireballs in Jupiter's atmosphere, which provide information not only on Jupiter's gravitational influence but also on the properties and populations of the impactors. Photometric monitoring of stellar occultations by the planets can reveal spatial/temporal variability in their atmospheric structure. Co-ordination and communication between professionals and amateurs is therefore important. We present examples of such collaborations that: (i) engage systematic multi-wavelength observations and databases, (ii) examine the variability of cloud features over timescales from days to decades, (iii) provide, by ground-based professional and amateur observations, the necessary spatial and temporal resolution of features that will be studied by the interplanetary mission Juno, (iv) investigate video observations of Jupiter to identify impacts of small objects, (v) carry out stellar-occultation campaigns. [ABSTRACT FROM AUTHOR]

Published
2016

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