Article
Astronomy & Astrophysics
A. Santamaria-Miranda, I. de Gregorio-Monsalvo, A. L. Plunkett, N. Huelamo, C. Lopez, A. Ribas, M. R. Schreiber, K. Muzic, A. Palau, L. B. G. Knee, A. Bayo, F. Comeron, A. Hales
Summary: The study aims to identify and characterize pre- and proto-BDs, as well as Class II BDs in Lupus 1 and 3 molecular clouds using ALMA observations. The results suggest that the sources in the sample are likely formed as a scaled-down version of low-mass star formation, with disk fragmentation potentially responsible for a considerable fraction of BDs.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
S. G. Parsons, B. T. Gansicke, M. R. Schreiber, T. R. Marsh, R. P. Ashley, E. Breedt, S. P. Littlefair, H. Meusinger
Summary: Magnitude-limited samples have shown that a higher percentage of cataclysmic variables contain white dwarfs with strong magnetic fields compared to single white dwarfs. The lack of identifiable progenitor systems for magnetic cataclysmic variables presents challenges in understanding their formation and evolution. In a sample of magnetic white dwarfs in detached binaries, it is found that they are more massive and have cooling ages of over 1Gyr, residing in systems close to Roche lobe filling. Unusual asymmetric light curves may be a way to identify these systems in larger numbers in the future.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Matthias R. Schreiber, Diogo Belloni, Boris T. Gansicke, Steven G. Parsons, Monica Zorotovic
Summary: The study investigates the origin of magnetic fields in white dwarfs and their impact on binary star systems. By incorporating evolutionary models, it is found that cataclysmic variables have a higher proportion of strongly magnetic white dwarfs, which can be explained by core crystallization and rotation-driven dynamo mechanisms.
Article
Astronomy & Astrophysics
A. F. Pala, B. T. Gansicke, D. Belloni, S. G. Parsons, T. R. Marsh, M. R. Schreiber, E. Breedt, C. Knigge, E. M. Sion, P. Szkody, D. Townsley, L. Bildsten, D. Boyd, M. J. Cook, D. De Martino, P. Godon, S. Kafka, V Kouprianov, K. S. Long, B. Monard, G. Myers, P. Nelson, D. Nogami, A. Oksanen, R. Pickard, G. Poyner, D. E. Reichart, D. Rodriguez Perez, J. Shears, R. Stubbings, O. Toloza
Summary: This article reports on the masses, effective temperatures, and secular mean accretion rates of 43 cataclysmic variable white dwarfs. The study reveals that there is no evidence of mass evolution with orbital period and identifies systems with low white dwarf masses that are most likely helium-core white dwarfs. It also suggests the presence of an additional mechanism of angular momentum loss that is more efficient at low white dwarf masses.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
M. S. Hernandez, M. R. Schreiber, S. G. Parsons, B. T. Gansicke, O. Toloza, G. Tovmassian, M. Zorotovic, F. Lagos, R. Raddi, A. Rebassa-Mansergas, J. J. Ren, C. Tappert
Summary: Establishing a large sample of post-common-envelope binaries (PCEBs) that consist of a white dwarf plus an intermediate mass companion star of spectral type AFGK, offers the potential to provide new constraints on theoretical models of white dwarf binary formation and evolution. Two new systems, TYC 110-755-1 and TYC 3858-1215-1, have been analyzed in detail in this study. The orbital periods of the two systems were found to be similar to 0.85 and similar to 1.64 d, respectively. The mass of the white dwarf in TYC 110-755-1 was measured to be 0.78 M-circle dot using HST spectroscopy. TESS high-time-resolution photometry revealed that both secondary stars were magnetically extremely active.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
F. Lagos, M. R. Schreiber, S. G. Parsons, O. Toloza, B. T. Gansicke, M. S. Hernandez, L. Schmidtobreick, D. Belloni
Summary: This study presents the discovery of three binary systems with eccentric orbits and orbital periods ranging from 10 to 42 days. Based on observations, two of these systems are likely triple systems, while the other one could be either a binary or a hierarchical triple. Interestingly, none of these systems are post-common envelope binaries, indicating a transition between two different mechanisms responsible for the formation of very close and somewhat wider WD + AFGK binaries.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Matthias R. Schreiber, Diogo Belloni, Monica Zorotovic, Sarai Zapata, Boris T. Gansicke, Steven G. Parsons
Summary: The origin of strong magnetic fields in white dwarfs has puzzled scientists for decades. A proposed dynamo mechanism operating in rapidly rotating and crystallizing white dwarfs may explain the occurrence of strong magnetic fields in white dwarfs with low-mass main-sequence star companions. This study investigates whether the same mechanism can produce strong magnetic fields in close double white dwarfs. The findings suggest that a rotation-and crystallization-driven dynamo plays a major role in the generation of strong magnetic fields in white dwarfs, as supported by the incidence of magnetic fields in close double white dwarfs.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
M. S. Hernandez, M. R. Schreiber, S. G. Parsons, B. T. Gansicke, O. Toloza, M. Zorotovic, R. Raddi, A. Rebassa-Mansergas, J. J. Ren
Summary: The white dwarf binary pathways survey focuses on studying the origin and evolution of white dwarf and intermediate-mass companion star binaries. In this paper, we present CPD-65 264, a new post-common envelope binary system consisting of a massive white dwarf and an intermediate-mass main-sequence secondary star. Through spectroscopic analysis, we characterized the secondary star and measured the orbital period. TESS observations also revealed significant starspots on the surface of the secondary star. The study suggests that the secondary star exhibits latitudinal differential rotation, making it the second example of a G-type secondary star in a post-common envelope binary system. Given the relative mass and short orbital period of the white dwarf, future mass transfer in the system will be stable, leading to the system evolving into a cataclysmic variable.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
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. G. Parsons, M. S. Hernandez, O. Toloza, M. Zorotovic, M. R. Schreiber, B. T. Gansicke, F. Lagos, R. Raddi, A. Rebassa-Mansergas, J. J. Ren, D. Koester
Summary: Virtually all binaries consisting of a white dwarf with a non-degenerate companion can be classified as close post-interaction systems or wide systems. Binaries with periods between these two extremes can provide valuable information about common envelope efficiency and alternative pathways in the creation of compact binaries. The discovery of three white dwarfs in binaries with evolved subgiant stars sheds light on the formation process of these systems and their future evolution.
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
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
Diogo Belloni, Matthias R. Schreiber
Summary: This study demonstrates that cataclysmic variables (CVs) with evolved donors are likely progenitors of AM CVn binaries. It is found that if the donor develops a significant helium core prior to mass transfer, the surface hydrogen abundance of AM CVn binaries will substantially decrease and become undetectable. Additionally, the CV formation channel can explain the observed AM CVn binaries with low mass and bloated donor stars.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
S. G. Parsons, M. S. Hernandez, O. Toloza, M. Zorotovic, M. R. Schreiber, B. T. Gansicke, F. Lagos, R. Raddi, A. Rebassa-Mansergas, J. J. Ren, D. Koester
Summary: This study presents three white dwarfs in binaries with evolved subgiant stars with orbital periods of 41, 52, and 461 days. These low mass white dwarfs are likely formed from stable but non-conservative mass transfer, and one system is part of a hierarchical triple star system.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)