454 citations · 7.2k across the 161 of their papers we have counts for
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A census of massive eclipsing binaries in the Whirlpool Galaxy
Cheyanne Shariat, Kareem El-Badry, Maude Gull +3
We present a census of massive eclipsing binary (EB) candidates in the Whirlpool Galaxy (M51), a face-on spiral galaxy at 7.5 Mpc with . Using 34 epochs of red-optic…
Mass-dependent multiplicity fraction in low mass stars revealed by Gaia astrometry
Ben Pennell, Hans-Walter Rix, Kareem El-Badry +3
Stellar multiplicity at different orbital periods is probed by different techniques: radial velocities at the shortest periods, direct imaging at the longest, and astrometry in bet…
Black hole astrometric binaries in the Roman Galactic Bulge Time Domain Survey
Casey Y. Lam, Jessica R. Lu, Kareem El-Badry +6
The Nancy Grace Roman Space Telescope (Roman), NASA's next flagship mission, is currently scheduled to launch in August 2026. As part of its mission, Roman will conduct the Galacti…
Spectroscopic follow-up of compact object binary candidates from Gaia DR3: White dwarfs, neutron stars, black holes, and the parallax zeropoint
Kareem El-Badry, David W. Latham, Hans-Walter Rix +12
Astrometry and radial velocities (RVs) from Gaia DR3 yielded orbits for hundreds of thousands of binary systems, including several samples proposed to contain black holes (BHs), ne…
A Galactic intermediate-mass stripped star with a Wolf-Rayet-like wind
Johanna Müller-Horn, Kareem El-Badry, Andreas A. C. Sander +17
Binary interaction in massive stars is expected to produce a large population of intermediate-mass (- M) envelope-stripped stars, yet such objects have remained elusi…
Unveiling Massive Main-Sequence Stars in Sextans A through Panchromatic Photometry
Maude Gull, Daniel R. Weisz, Yumi Choi +9
We present a study of the metal-poor (~6% Z_sun) massive (>8 M_sun) main-sequence star population in the star-forming dwarf galaxy Sextans A. By modeling near-UV to near-IR photome…
Hide and Seek with Gaia. Detectability of Predicted Thin-Disc Metal-Rich RR Lyrae Binaries in Gaia DR3 and DR4
Giuliano Iorio, Pranav Nagarajan, Alexey Bobrick +8
RR Lyrae stars (RRLs) are classical tracers of old stellar populations, yet growing evidence suggests the presence of a metal-rich ([Fe/H]>-0.5), intermediate-age (2-7 Gyr) sub-pop…
BE Lyncis is not a Black Hole Binary: Lessons From Gaia and Hipparcos Astrometry
Pranav Nagarajan, Kareem El-Badry, Thomas J. Maccarone +3
BE Lyncis (BE Lyn) is a well-studied high-amplitude Scuti variable star (HADS). Recently, Niu et al. (2026) analyzed a 39-year baseline of times of maximum light of BE Lyn, rep…
The physical properties of post-mass-transfer binaries
Rhys Seeburger, Hans-Walter Rix, Kareem El-Badry +4
Aims. We present and analyse the detailed physical properties of six binary stellar systems, originally proposed as possible star-black hole binaries on the basis of radial velocit…
Dormant black hole candidates from Gaia DR3 summary diagnostics
Johanna Müller-Horn, Hans-Walter Rix, Kareem El-Badry +4
We present a rigorous identification of candidates for dormant black holes (BHs) and neutron stars (NSs) in binaries using summary statistics from Gaia DR3, rather than full orbita…
Complex spectral variability and hints of a luminous companion in the Be star + black hole binary candidate ALS 8814
Kareem El-Badry, Matthias Fabry, Hugues Sana +2
The emission-line binary ALS 8814 was recently proposed as a Be star + black hole (BH) binary based on large-amplitude radial velocity (RV) variations of a Be star and non-detectio…
A Spectroscopic Search for Dormant Black Holes in Low-Metallicity Binaries
Pranav Nagarajan, Kareem El-Badry, Henrique Reggiani +9
The discovery of the massive black hole (BH) system Gaia BH3 in pre-release Gaia DR4 data suggests that wide BH binaries with luminous companions may be significantly overrepresent…
Double White Dwarf Binaries in SDSS-V DR19 : The discovery of a rare DA+DQ white dwarf binary with 31 hour orbital period
Gautham Adamane Pallathadka, Vedant Chandra, Boris T. Gansicke +13
Binaries of two white dwarfs (WDs) are an important class of astrophysical objects that are theorized to lead to Type Ia supernovae and are also used to gain insight into complex p…
Millions of Main-Sequence Binary Stars from Gaia BP/RP Spectra
Jiadong Li, Hans-Walter Rix, Yuan-Sen Ting +6
We present the main-sequence binary (MSMS) Catalog derived from Gaia Data Release 3 BP/RP (XP) spectra. Leveraging the vast sample of low-resolution Gaia XP spectra, we develop a f…
How to use Gaia parallaxes for stars with poor astrometric fits
Kareem El-Badry
Gaia parallax measurements for stars with poor astrometric fits -- as evidenced by high renormalized unit weight error (RUWE) -- are often assumed to be unreliable, but the extent…
Population demographics of white dwarf binaries with intermediate separations: Gaia constraints on post-AGB mass transfer
Natsuko Yamaguchi, Kareem El-Badry, Sahar Shahaf
Astrometry from the Gaia mission has revealed a large population of white dwarf (WD) + main sequence (MS) binaries with periods of d. These systems have separations i…
HIP 15429: A newborn Be star on an eccentric binary orbit
Johanna Müller-Horn, Kareem El-Badry, Hans-Walter Rix +9
We identified a new post-interaction binary, HIP 15429, consisting of a stripped star and a recently formed, rapidly rotating Be star companion ( km/s) sharin…
Resolution of a paradox: SDSS J1257+5428 can be explained as a descendant of a cataclysmic variable with an evolved donor
Diogo Belloni, Matthias R. Schreiber, Kareem El-Badry
The existence of the binary system SDSS J1257+5428 has been described as paradoxical. Here we investigate under which conditions SDSS J1257+5428 could be understood as a descendant…
Discovery of two new polars evolved past the period bounce
Tim Cunningham, Ilaria Caiazzo, Gracjan Sienkiewicz +13
We report the discovery of two new magnetic cataclysmic variables with brown dwarf companions and long orbital periods ( and min). This discovery incr…
Unevolved Li-rich stars at low metallicity: a possible formation pathway through novae
Tadafumi Matsuno, Alex Kemp, Ataru Tanikawa +7
A small fraction of low-mass stars have been found to have anomalously high Li abundances. Although it has been suggested that mixing during the red giant branch phase can lead to…
Variability of Central Stars of Planetary Nebulae with the Zwicky Transient Facility. II. Long-Timescale Variables including Wide Binary and Late Thermal Pulse Candidates
Soumyadeep Bhattacharjee, Nicole Reindl, Howard E. Bond +14
In this second paper on our variability survey of central stars of planetary nebulae (CSPNe) using ZTF, we report 11 long-timescale variables with variability timescales ranging fr…
A ZTF Search for Circumstellar Debris Transits in White Dwarfs: Six New Candidates, one with Gas Disk Emission, identified in a Novel Metric Space
Soumyadeep Bhattacharjee, Zachary P. Vanderbosch, Mark A. Hollands +13
White dwarfs (WDs) showing transits from orbiting planetary debris provide significant insights into the structure and dynamics of debris disks. This is a rare class of objects wit…
A Link Between White Dwarf Pulsars and Polars: Multiwavelength Observations of the 9.36-Minute Period Variable Gaia22ayj
Antonio C. Rodriguez, Kareem El-Badry, Pasi Hakala +30
White dwarfs (WDs) are the most abundant compact objects, and recent surveys have suggested that over a third of WDs in accreting binaries host a strong (B 1 MG) magnetic…
Cyclotron emitting magnetic white dwarfs in post common envelope binaries discovered with the Zwicky Transient Facility
J. van Roestel, A. C. Rodriguez, P. Szkody +20
We present the discovery of 14 new (and recovery of 4 known) low accretion rate magnetic white dwarfs in post-common envelope binaries that emit strong cyclotron emission using the…