Article
Astronomy & Astrophysics
S. Geier, M. Dorsch, I Pelisoli, N. Reindl, U. Heber, A. Irrgang
Summary: Hot subdwarf stars are likely formed by close binary interactions and represent a late stage in the evolution of low-mass stars. A study of radial velocity variability reveals completely different behavior between He-poor and He-rich hot subdwarfs. There is likely no evolutionary connection between these subtypes, and the majority of hot subdwarf stars are formed through binary merger channels.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
V Schaffenroth, S. L. Casewell, D. Schneider, D. Kilkenny, S. Geier, U. Heber, A. Irrgang, N. Przybilla, T. R. Marsh, S. P. Littlefair, V. S. Dhillon
Summary: Subdwarf B stars are core-helium-burning stars located on the extreme horizontal branch (EHB), formed through extensive mass loss on the red giant branch. The system J08205+0008 with a hot subdwarf and substellar companion was analyzed in-depth using high-quality data and various methods, leading to precise constraints on the characteristics of both stars. The hot subdwarf was found to have a mass of 0.39-0.50 Solar masses, while the companion is likely a massive brown dwarf with a mass of 0.061-0.071 Solar masses.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
V Schaffenroth, S. L. Casewell, D. Schneider, D. Kilkenny, S. Geier, U. Heber, A. Irrgang, N. Przybilla, T. R. Marsh, S. P. Littlefair, V. S. Dhillon
Summary: Subdwarf B stars are core-helium-burning stars located on the extreme horizontal branch, requiring extensive mass loss on the red giant branch for their formation. Through in-depth analysis of the system, chemical abundances, rotational velocity, and radius constraints of the hot subdwarf and its companion were derived. The study suggests that the companion is most likely a massive brown dwarf based on various observational methods.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
P. Nemeth, J. Vos, F. Molina, A. Bastian
Summary: This study aims to investigate the chemical composition and Galactic kinematics of the spectroscopic binary SB 744, revealing it as an old Population II system with a heavy-metal subclass hot subdwarf star and super-solar lead abundances. The presence of fluorine suggests a past hierarchical triple system or single-star evolution through late core helium flash and atmospheric mixing to explain the observed abundances.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
F. Kahraman Alicavus, T. Pawar, K. G. Helminiak, G. Handler, A. Moharana, F. Alicavus, P. De Cat, F. Leone, G. Catanzaro, M. Giarrusso, N. Ukita, E. Kambe
Summary: Pulsating eclipsing binary systems are important for studying stellar interiors and determining fundamental stellar parameters. In this study, the pulsating detached eclipsing binary system AI Hya was analyzed. The more luminous component was found to be a massive, cool, and chemically normal star, while the hotter component was slightly metal-rich. The age of the system was determined to be 850 +/- 20 Myr, and both binary components were found to be located in the delta Scuti instability strip. The frequency analysis revealed pulsation frequencies between 5.5 and 13.0 d(-1), with origins from both binary components.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Nicole Reindl, Ramazan Islami, Klaus Werner, S. O. Kepler, Max Pritzkuleit, Harry Dawson, Matti Dorsch, Alina Istrate, Ingrid Pelisoli, Stephan Geier, Murat Uzundag, Judith Provencal, Stephen Justham
Summary: We report on the spectroscopic confirmation of 68 new bright and blue white dwarfs, which nearly doubles the number of the hottest known white dwarfs. We also discovered new types of white dwarfs and found that a significant fraction of them exhibit photometric variability. These findings are important for understanding the formation and evolution of white dwarfs.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
H. Xiong, L. Casagrande, X. Chen, J. Vos, X. Zhang, S. Justham, J. Li, T. Wu, Y. Li, Z. Han
Summary: Blue large-amplitude pulsators (BLAPs) are a newly discovered and extremely rare type of variable star. Their origins and internal structures have attracted a great deal of attention. This study uses MESA models to explore whether shell helium-burning subdwarfs type B (SHeB sdBs) can explain the properties of BLAPs. The models that best match existing observational constraints have helium core masses in the range of 0.45-0.5 solar masses and predict a possible change from positive to negative rate of period change. Binary evolution is a potential formation channel for SHeB sdBs.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Klaus Werner, Nicole Reindl, Matti Dorsch, Stephan Geier, Ulisse Munari, Roberto Raddi
Summary: Hot, compact, hydrogen-deficient pre-white dwarfs are rare objects that are believed to be the outcome of either single star evolution or binary star evolution. Their study is important for understanding the physics of thermonuclear flashes and merger events. Spectroscopically, they are divided into three different classes, namely PG1159, O(He), or He-sdO. This study presents a spectroscopic analysis of five such stars and found that some of them have hydrogen content that cannot be explained by current evolution models.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Kareem El-Badry, Eliot Quataert
Summary: HR 6819 was originally believed to be a triple star system, but is actually a binary system without a black hole. It consists of a rapidly rotating Be star and a slowly rotating B star, with the B star being at least 10 times less massive than the Be star. The B star is thought to be a bloated, recently stripped helium star that is currently contracting to become a hot subdwarf.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
A. S. Baran, R. H. Ostensen, U. Heber, A. Irrgang, S. Sanjayan, J. H. Telting, M. D. Reed, J. Ostrowski
Summary: This study provides an overview of HW-Vir type eclipsing systems based on space observations from the TESS mission. The analysis focuses on AA Doradus, with detailed examination of its properties and confirmation of stable orbital period through eclipse timing measurements. The study also suggests possible pulsations in the system, which will be confirmed or rejected with further cadence data in the future.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Francisco Molina, Joris Vos, Peter Nemeth, Roy Ostensen, Maja Vuckovic, Andrew Tkachenko, Hans van Winckel
Summary: This study solves the orbital and atmospheric parameters of two long-period sdO binaries and investigates the chemical composition of their main-sequence companions for the first time. The results show a depletion of yttrium in both systems and a C overabundance in BD-11(o)162. Feige 80 matches the same correlation as the majority of the systems, while BD-11(o)162 is an exceptional system with a lower mass and a higher progenitor mass may have caused the C overabundance. The depletion of yttrium in the MS companions could indicate the existence of a circumbinary disk in these systems' pasts.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Yangyang Zhang, Hailiang Chen, Xuefei Chen, Zhanwen Han
Summary: The study demonstrates that the mass transfer scheme can significantly influence the evolution of red giant binaries, resulting in differences in final donor masses and orbital periods. Models using the 'Kolb' scheme show larger orbital periods compared to the 'classical' scheme under the same donor mass conditions.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
E. J. Snowdon, C. S. Jeffery, S. Schlagenhauf, M. Dorsch, I. M. Monageng
Summary: Hot subdwarfs are a type of stars located between the main sequence and the white dwarf sequence. They have diverse properties and mostly unknown origins. By studying Ton S 415, researchers have confirmed that it is a close binary star with an unseen white dwarf companion. The analysis of its spectrum and light curves has provided information about its physical properties and predicted its evolutionary pathway.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Huseyin Er, Aykut Ozdonmez, Ilham Nasiroglu
Summary: Several post-common envelope eclipsing binaries have been found to have variations in their orbital periods, potentially due to the presence of additional bodies in the system or other physical effects. The sdB+M eclipsing system NY Vir has shown such variations in the past decade, with recent observations indicating a new trend in the O - C diagram. Further research is needed to understand the mechanism behind these changes.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
R. Culpan, S. Geier, N. Reindl, I Pelisoli, N. Gentile Fusillo, A. Vorontseva
Summary: Based on the ongoing spectroscopic surveys and Gaia EDR3 data, this study compiled new releases of two catalogues of hot subluminous stars. The new catalogues provide more observational sources, improved accuracy in astrometry, and refined selection functions, particularly in crowded regions of the Galactic plane and towards the Magellanic Clouds.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Chris Evans, Stefano Cristiani, Cyrielle Opitom, Gabriele Cescutti, Valentina D'Odorico, Juan Manuel Alcala, Silvia H. P. Alencar, Sergei Balashev, Beatriz Barbuy, Nate Bastian, Umberto Battino, Pamela Cambianica, Roberta Carini, Brad Carter, Santi Cassisi, Bruno Vaz Castilho, Norbert Christlieb, Ryan Cooke, Stefano Covino, Gabriele Cremonese, Katia Cunha, Andre R. da Silva, Valerio D'Elia, Annalisa De Cia, Gayandhi De Silva, Marcos Diaz, Paolo Di Marcantonio, Heitor Ernandes, Alan Fitzsimmons, Mariagrazia Franchini, Boris T. Gansicke, Matteo Genoni, Riano E. Giribaldi, Andrea Grazian, Camilla Juul Hansen, Fiorangela La Forgia, Monica Lazzarin, Wagner Marcolino, Marcella Marconi, Alessandra Migliorini, Pasquier Noterdaeme, Claudio Pereira, Bogumil Pilecki, Andreas Quirrenbach, Sofia Randich, Silvia Rossi, Rodolfo Smiljanic, Colin Snodgrass, Julian Stuermer, Andrea Trost, Eros Vanzella, Paolo Ventura, Duncan Wright, Tayyaba Zafar
Summary: This paper introduces the scientific motivations for the development of the Cassegrain U-Band Efficient Spectrograph (CUBES) for the Very Large Telescope. It covers a wide range of astronomical topics where current ground-based spectrographs are limited. Each topic's background is presented, and specific technical requirements for the instrument design are identified. The CUBES design aims to greatly improve the efficiency of astronomical spectroscopy over a specific wavelength range, and its predicted performance is compared to existing facilities.
EXPERIMENTAL ASTRONOMY
(2023)
Article
Astronomy & Astrophysics
Mairi W. O'Brien, P-E Tremblay, N. P. Gentile Fusillo, M. A. Hollands, B. T. Gansicke, D. Koester, I Pelisoli, E. Cukanovaite, T. Cunningham, A. E. Doyle, A. Elms, J. Farihi, J. J. Hermes, J. Holberg, S. Jordan, B. L. Klein, S. J. Kleinman, C. J. Manser, D. De Martino, T. R. Marsh, J. McCleery, C. Melis, A. Nitta, S. G. Parsons, R. Raddi, A. Rebassa-Mansergas, M. R. Schreiber, R. Silvotti, D. Steeghs, O. Toloza, S. Toonen, S. Torres, A. J. Weinberger, B. Zuckerman
Summary: We conducted a spectroscopic survey of 248 white dwarf candidates within a distance of 40 pc from the Sun, with 244 of them located in the Southern hemisphere. Using the Very Large Telescope and Southern Astrophysical Research Telescope, we confirmed a total of 246 white dwarfs, with 209 having no previously published spectra. Among the identified white dwarfs, 100 display hydrogen Balmer lines, 69 have featureless spectra, and two show only neutral helium lines. Additionally, we observed 35 magnetic white dwarfs through Zeeman splitting of their spectral lines.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
S. Scaringi, M. Monguio, C. Knigge, M. Fratta, B. Gaensicke, P. J. Groot, A. Rebassa-Mansergas, O. Toloza
Summary: This paper presents a sub-arcsec cross-match of Gaia DR3 with IGAPS and UKIDSS, resulting in a catalogue called XGAPS. The XGAPS catalogue provides additional precise photometry to Gaia photometry and has various applications, such as selecting Galactic targets for spectroscopic surveys and identifying specific Galactic populations.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Felipe Lagos, Monica Zorotovic, Matthias R. Schreiber, B. T. Gansicke
Summary: The recently discovered system Gaia 0007-1605, consisting of a white dwarf with a brown dwarf companion and a distant white dwarf tertiary, resembles the triple system WD 1856+534, which is the first transiting planet candidate around a white dwarf. The formation of the inner binary in Gaia 0007-1605 could be attributed to either common envelope evolution, triple dynamics, or a combination of both mechanisms. The energy budget and Von Zeipel-Lidov-Kozai oscillations play important roles in understanding the system's current configuration.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Antonio C. Rodriguez, Shrinivas R. Kulkarni, Thomas A. Prince, Paula Szkody, Kevin B. Burdge, Ilaria Caiazzo, Jan van Roestel, Zachary P. Vanderbosch, Kareem El-Badry, Eric C. Bellm, Boris T. Gensicke, Matthew J. Graham, Ashish A. Mahabal, Frank J. Masci, Przemek Mroz, Reed Riddle, Ben Rusholme
Summary: Two new magnetic cataclysmic variables (CVs) have been discovered through crossmatching the eFEDS catalog with photometry data, one of which is pulsating and the other is non-pulsating.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Andrew P. Cooper, Sergey E. Koposov, Carlos Allende Prieto, Christopher J. Manser, Namitha Kizhuprakkat, Adam D. Myers, Arjun Dey, Boris T. Gansicke, Ting S. Li, Constance Rockosi, Monica Valluri, Joan Najita, Alis Deason, Anand Raichoor, M. -Y. Wang, Y. -S. Ting, Bokyoung Kim, Andreia Carrillo, Wenting Wang, Leandro Beraldo e Silva, Jiwon Jesse Han, Jiani Ding, Miguel Sanchez-Conde, Jessica N. Aguilar, Steven Ahlen, Stephen Bailey, Vasily Belokurov, David Brooks, Katia Cunha, Kyle Dawson, Axel de la Macorra, Peter Doel, Daniel J. Eisenstein, Parker Fagrelius, Kevin Fanning, Andreu Font-Ribera, Jaime E. Forero-Romero, Enrique Gaztanaga, Satya Gontcho A. Gontcho, Julien Guy, Klaus Honscheid, Robert Kehoe, Theodore Kisner, Anthony Kremin, Martin Landriau, Michael E. Levi, Paul Martini, Aaron M. Meisner, Ramon Miquel, John Moustakas, Jundan J. D. Nie, Nathalie Palanque-Delabrouille, Will J. Percival, Claire Poppett, Francisco Prada, Nabeel Rehemtulla, Edward Schlafly, David Schlegel, Michael Schubnell, Ray M. Sharples, Gregory Tarle, Risa H. Wechsler, David H. Weinberg, Zhimin Zhou, Hu Zou
Summary: We describe the Milky Way Survey (MWS), which will be conducted with the Dark Energy Spectroscopic Instrument (DESI), aiming to observe approximately seven million stars and investigate the Galactic structure and stellar evolution. The MWS target selection scheme focuses on the thick disk and stellar halo, including rare stellar types such as white dwarfs, low-mass stars near the Sun, and horizontal branch stars. Our pipelines for deriving radial velocities, atmospheric parameters, and chemical abundances are validated using the DESI Survey Validation program (SV) data, showing good agreement with expectations from mock catalogs and previous surveys.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Christopher J. Manser, Boris T. Gansicke, Keith Inight, Akshay Robert, S. Ahlen, C. Allende Prieto, D. Brooks, A. P. Cooper, A. de la Macorra, A. Font-Ribera, K. Honscheid, T. Kisner, M. Landriau, Aaron M. Meisner, R. Miquel, Jundan Nie, C. Poppett, Gregory Tarle, Zhimin Zhou
Summary: A new class of white dwarfs, called DAHe, has been discovered to have Zeeman-split Balmer lines in emission, but the origins of these emission lines are still unknown. By studying a sample of 21 newly identified DAHe systems, researchers have determined the magnetic field strengths and rotation periods of these systems. These DAHe systems cluster together on the Gaia Hertzsprung-Russell diagram and represent about 1% of white dwarfs in that region.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Odette Toloza, Boris T. Gansicke, Laura M. Guzman-Rincon, Tom R. Marsh, Paula Szkody, Matthias R. Schreiber, Domitilla de Martino, Monica Zorotovic, Kareem El-Badry, Detlev Koester, Felipe Lagos
Summary: Research suggests that white dwarfs that accrete from non-degenerate companions exhibit abnormal carbon and nitrogen abundances in their stellar components, indicating they may be descendants of supersoft X-ray binaries. Measuring the carbon-to-nitrogen abundance ratio can provide insights into their past evolution. By analyzing far-ultraviolet spectroscopy of the cataclysmic variable HS 0218 + 3229, it was found that the ratio of carbon-to-nitrogen is about one tenth of the solar value. Other elemental abundances were also estimated, and the system's past was reconstructed. The study predicts that HS 0218 + 3229 will evolve to a period minimum below 76.2 +/- 1 minutes for normal cataclysmic variables.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Abbigail K. Elms, Pier-Emmanuel Tremblay, Boris T. Gaensicke, Andrew Swan, Carl Melis, Antoine Bedard, Christopher J. Manser, James Munday, J. J. Hermes, Erik Dennihy, Atsuko Nitta, Ben Zuckerman
Summary: Two recently discovered white dwarfs, WD J041246.84 + 754942.26 and WD J165335.21 - 100116.33, exhibit H alpha and H beta Balmer line emission similar to stars in the emerging DAHe class, yet intriguingly have not been found to have detectable magnetic fields. These white dwarfs are assigned the spectral type DAe. We present detailed follow-up of the two known DAe stars using new time-domain spectroscopic observations and analysis of the latest photometric time-series data from TESS and ZTF. We measure the upper magnetic field strength limit of both stars as B < 0.05 MG.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
A. Rebassa-Mansergas, J. Maldonado, R. Raddi, S. Torres, M. Hoskin, T. Cunningham, M. A. Hollands, J. Ren, B. T. Gansicke, P-E Tremblay, M. Camisassa
Summary: Magnetic activity and rotation are related to the age of low-mass main-sequence stars. The rotational velocities tend to decrease over time, but there are moderately old stars that rotate faster than expected. The activity fractions for stars younger than 5 Gyr range between 10% and 40%, while older stars may also have higher activity fractions.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Keith Inight, Boris T. Gaensicke, Elme Breedt, Henry T. Israel, Stuart P. Littlefair, Christopher J. Manser, Tom R. Marsh, Tim Mulvany, Anna Francesca Pala, John R. Thorstensen
Summary: We present a catalogue of 507 cataclysmic variables (CVs) observed in SDSS I to IV, including 70 new classifications. This sample provides unbiased space densities and period distributions for different CV sub-types. The study also reports on peculiar CVs, period bouncers, and CVs with large changes in accretion rates. The catalogue and material included in it will be useful for observational population studies of CVs.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Pablo Rodriguez-Gil, Jesus M. Corral-Santana, N. Elias-Rosa, Boris T. Gansicke, Margarita Hernanz, Gloria Sala
Summary: This study presents the first reliable determination of the orbital period of the recurrent nova V2487 Oph. The derived value is significantly shorter than previous claims, making V2487 Oph one of the longest period cataclysmic variables known. The analysis of the spectra suggests that the broad Balmer absorptions in V2487 Oph come from an accretion disc viewed at low inclination.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Multidisciplinary Sciences
Ilaria Caiazzo, Kevin B. Burdge, Pier-Emmanuel Tremblay, James Fuller, Lilia Ferrario, Boris T. Gansicke, J. J. Hermes, Jeremy Heyl, Adela Kawka, S. R. Kulkarni, Thomas R. Marsh, Przemek Mroz, Thomas A. Prince, Harvey B. Richer, Antonio C. Rodriguez, Jan van Roestel, Zachary P. Vanderbosch, Stephane Vennes, Dayal Wickramasinghe, Vikram S. Dhillon, Stuart P. Littlefair, James Munday, Ingrid Pelisoli, Daniel Perley, Eric C. Bellm, Elme Breedt, Alex J. Brown, Richard Dekany, Andrew Drake, Martin J. Dyer, Matthew J. Graham, Matthew J. Green, Russ R. Laher, Paul Kerry, Steven G. Parsons, Reed L. Riddle, Ben Rusholme, Dave I. Sahman
Summary: White dwarfs, the dense remnants of dead stars, have a mass comparable to the Sun compressed into the size of a planet.The composition of a white dwarf's atmosphere can change as it cools, with some transitioning from a hydrogen-dominated atmosphere to a helium-dominated one. The observed white dwarf ZTF J203349.8+322901.1 shows a peculiar nature, with one side of its atmosphere dominated by hydrogen and the other by helium. This may be caused by the presence of a small magnetic field, creating temperature, pressure, or mixing variations.
Article
Astronomy & Astrophysics
Na'ama Hallakoun, Dan Maoz, Alina G. Istrate, Carles Badenes, Elme Breedt, Boris T. Gansicke, Saurabh W. Jha, Bruno Leibundgut, Filippo Mannucci, Thomas R. Marsh, Gijs Nelemans, Ferdinando Patat, Alberto Rebassa-Mansergas
Summary: We report observations of an extremely irradiated low-mass companion to the hot white dwarf WD 0032-317. Our analysis indicates a day-side temperature of about 8000K and a day-to-night temperature difference of about 6000K. The extreme-ultraviolet radiation received by WD 0032-317B is equivalent to that received by planets orbiting close to hot stars and about 5600 times higher than that of KELT-9b. With a mass of about 75-88 Jupiter masses, this near-hydrogen-burning-limit object is potentially one of the most massive brown dwarfs known.
Article
Astronomy & Astrophysics
K. E. Harborne, A. Serene, E. J. A. Davies, C. Derkenne, S. Vaughan, A. I. Burdon, C. del P. Lagos, R. Mcdermid, S. O'Toole, C. Power, A. S. G. Robotham, G. Santucci, R. Tobar
Summary: This work presents a methodology and code-base for constructing mock IFS observations of simulated galaxies, aiming to improve collaboration and comparison between observation and theory, and accelerate our understanding of galaxy kinematics evolution. The open-source package SimSpin, written in R, can be interacted with in any coding language via an API interface and is being utilized by international IFS collaborations.
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF AUSTRALIA
(2023)