106 citations · 446 across the 37 of their papers we have counts for
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Radial Velocity Orbital Solutions for Candidate Black Hole and Neutron Star Binary Systems in the Gaia Data Release 3 Catalog
Joshua D. Simon, Casey Y. Lam, Kareem El-Badry +8
We present spectroscopic followup observations of binary systems from the Gaia Data Release 3 (DR3) binary catalog that were selected to have large enough mass functions for their…
Chemical Signatures of AGB Mass Transfer in Gaia White Dwarf Companions
Natsuko Yamaguchi, Kareem El-Badry, Henrique Reggiani +2
We present a homogeneous abundance analysis of 160 main-sequence stars in astrometric white-dwarf + main-sequence (WD+MS) binaries with orbits from Gaia DR3. These systems have AU-…
Beyond OCCAM: Measuring Optical Neutron Capture Abundances of Open Cluster Stars
Natalie Myers, Sarah Loebman, Henrique Reggiani +1
Open clusters have long been used to determine ages of stars, as well as calibrate stellar evolution models and other methods of age-dating stellar groups, e.g., gyrochronology, as…
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…
Extreme Lithium Depletion in Solar Twins: Challenging Non-Standard Mixing Models
Isabelle Winnick, Jhon Yana Galarza, Henrique Reggiani +12
Lithium (Li) is a powerful tracer of stellar mixing, gradually depleted in solar twins by non-standard transport below the convective zone. Here, we identify six new solar twins wi…
HIP 8522: A Puzzling Young Solar Twin with the Lowest Detected Lithium
Jhon Yana Galarza, Diego Lorenzo-Oliveira, Thiago Ferreira +8
We present HIP 8522, a young solar twin with the lowest detected lithium, potentially a field blue straggler or the result of episodic early accretion. Its stellar parameters ($T_{…
Constraining Extra Mixing during the Main Sequence: What Depletes Lithium Does Not Touch Beryllium
Henrique Reggiani, Jhon Yana Galarza, Diego Lorenzo-Oliveira +4
Measurements of lithium abundances in solar-type stars have shown that standard models of stellar evolution are incapable of explaining the observed depletion as a function of stel…
Detailed abundances of the planet-hosting TOI-1173 A/B system: Possible evidence of planet engulfment in a very wide binary
Jhon Yana Galarza, Henrique Reggiani, Thiago Ferreira +7
Over the last decade, studies of large samples of binary systems identified chemical anomalies, and showed that they might be attributed to planet formation or planet engulfment. H…
Accurate, Precise, and Physically Self-consistent Ages and Metallicities for 400,000 Solar Neighborhood Subgiant Branch Stars
David M. Nataf, Kevin C. Schlaufman, Henrique Reggiani +1
Age is the most difficult fundamental stellar parameter to infer for isolated stars. While isochrone-based ages are in general imprecise for both main sequence dwarfs and red giant…
The Symbiotic X-ray Binary IGR J16194-2810: A Window on the Future Evolution of Wide Neutron Star Binaries From Gaia
Pranav Nagarajan, Kareem El-Badry, Casey Lam +1
We present optical follow-up of IGR J16194-2810, a hard X-ray source discovered by the INTEGRAL mission. The optical counterpart is a red giant at a distance of…
A neutron star candidate in a 2-year orbit
Kareem El-Badry, Joshua D. Simon, Henrique Reggiani +10
We report discovery and characterization of a main-sequence G star orbiting a dark object with mass . The system was discovered via Gaia astrometry and has…
Spectacular nucleosynthesis from early massive stars
Alexander P. Ji, Sanjana Curtis, Nicholas Storm +39
Stars formed with initial mass over 50 Msun are very rare today, but they are thought to be more common in the early universe. The fates of those early, metal-poor, massive stars a…
Insight into the Formation of Pic b through the Composition of Its Parent Protoplanetary Disk as Revealed by the Pic Moving Group Member HD 181327
Henrique Reggiani, Jhon Yana Galarza, Kevin C. Schlaufman +5
It has been suggested that Pic b has a supersolar metallicity and subsolar C/O ratio. Assuming solar carbon and oxygen abundances for the star Pic and therefore the planet'…
Iron-rich Metal-poor Stars and the Astrophysics of Thermonuclear Events Observationally Classified as Type Ia Supernovae. I. Establishing the Connection
Henrique Reggiani, Kevin C. Schlaufman, Andrew R. Casey
The progenitor systems and explosion mechanisms responsible for the thermonuclear events observationally classified as Type Ia supernovae are uncertain and difficult to uniquely co…
The Chemical Composition of Extreme-Velocity Stars
Henrique Reggiani, Alexander P. Ji, Kevin C. Schlaufman +5
Little is known about the origin of the fastest stars in the Galaxy. Our understanding of the Milky Way and surrounding dwarf galaxies chemical evolution history allows us to use t…
Searching for new solar twins: The Inti survey for the Northern Sky
J. Y. Galarza, R. López-Valdivia, D. Lorenzo-Oliveira +9
Solar twins are key in different areas of astrophysics, however only just over a hundred were identified and well-studied in the last two decades. In this work, we take advantage o…
The Most Metal-poor Stars in the Inner Bulge
Henrique Reggiani, Kevin C. Schlaufman, Andrew R. Casey +1
The bulge is the oldest component of the Milky Way. Since numerous simulations of Milky Way formation have predicted that the oldest stars at a given metallicity are found on tight…
An empirical metallicity tracer in CEMP and C-normal stars
D. Singh, C. J. Hansen, J. S. Byrgesen +2
Deriving the metallicity, [Fe/H], in low-resolution spectra of carbon-enhanced metal-poor (CEMP) stars is a tedious task that, owing to the large number of line blends, often leads…
The effect of stellar activity on the spectroscopic stellar parameters of the young solar twin HIP 36515
Jhon Yana Galarza, Jorge Meléndez, Diego Lorenzo-Oliveira +7
Spectroscopic equilibrium allows us to obtain precise stellar parameters in Sun-like stars. It relies on the assumption of the iron excitation and ionization equilibrium. However,…
G64-12 and G64-37 are Carbon-Enhanced Metal-Poor Stars
Vinicius M. Placco, Timothy C. Beers, Henrique Reggiani +1
We present new high-resolution chemical-abundance analyses for the well-known high proper-motion subdwarfs G64-12 and G64-37, based on very high signal-to-noise spectra (S/N ~ 700/…