Search Publications
Unresolved Binaries in the Intermediate Mass Range in the Pleiades Star Cluster
Carraro, Giovanni; Seleznev, Anton F.; Malofeeva, Alina A.
The identification of binary stars of different mass ratios in resolved stellar populations is a challenging task. We show how the photometric diagram constructed with the pseudocolors (H-W2)-W1 versus W2-(BP-K) can be employed to estimate the binary and multiple star ratios and the distribution of their component mass ratio q effectively. As an a…
Galactic Chemical Evolution of Exoplanet Hosting Stars: Are High-mass Planetary Systems Young?
Manoj, P.; Narang, Mayank; Swastik, C. +5 more
The imprints of stellar nucleosynthesis and chemical evolution of the galaxy can be seen in different stellar populations, with older generation stars showing higher α-element abundances and the later generations becoming enriched with iron-peak elements. The evolutionary connections and chemical characteristics of circumstellar disks, stars, and …
The COS CGM Compendium. IV. Effects of Varying Ionization Backgrounds on Metallicity Determinations in the z < 1 Circumgalactic Medium
Fox, Andrew J.; Lehner, Nicolas; Howk, J. Christopher +3 more
Metallicity estimates of circumgalactic gas based on absorption-line measurements typically require photoionization modeling to account for unseen ionization states. We explore the impact of uncertainties in the extreme-ultraviolet background (EUVB) radiation on such metallicity determinations for the z < 1 circumgalactic medium. In particular,…
Two Massive Jupiters in Eccentric Orbits from the TESS Full-frame Images
Butler, R. Paul; Vanderburg, Andrew; Bieryla, Allyson +43 more
We report the discovery of two short-period massive giant planets from NASA's Transiting Exoplanet Survey Satellite (TESS). Both systems, TOI-558 (TIC 207110080) and TOI-559 (TIC 209459275), were identified from the 30 minute cadence full-frame images and confirmed using ground-based photometric and spectroscopic follow-up observations from TESS's…
The LHS 1678 System: Two Earth-sized Transiting Planets and an Astrometric Companion Orbiting an M Dwarf Near the Convective Boundary at 20 pc
Kostov, Veselin B.; Torres, Guillermo; Barclay, Thomas +48 more
We present the Transiting Exoplanet Survey Satellite (TESS) discovery of the LHS 1678 (TOI-696) exoplanet system, comprised of two approximately Earth-sized transiting planets and a likely astrometric brown dwarf orbiting a bright (V J = 12.5, K s = 8.3) M2 dwarf at 19.9 pc. The two TESS-detected planets are of radius 0.7…
Spectroscopic Orbits of Subsystems in Multiple Stars. VIII.
Tokovinin, Andrei
Periods, eccentricities, and masses in hierarchical stellar systems inform us on the formation and early evolution of these fascinating objects. To complement the multiplicity statistics of nearby solar-type stars, 19 new spectroscopic orbits of inner subsystems in 15 hierarchies (10 triples and 5 quadruples) are determined based on high-resolutio…
The POKEMON Speckle Survey of Nearby M Dwarfs. I. New Discoveries
Kiman, Rocio; Ciardi, David R.; Clark, Catherine A. +4 more
M dwarfs are favorable targets for exoplanet detection with current instrumentation, but stellar companions can induce false positives and inhibit planet characterization. Knowledge of stellar companions is also critical to our understanding of how binary stars form and evolve. We have therefore conducted a survey of stellar companions around near…
Mapping the Pressure-dependent Day-Night Temperature Contrast of a Strongly Irradiated Atmosphere with HST Spectroscopic Phase Curve
Mayorga, L. C.; Apai, Dániel; Marley, Mark +6 more
Many brown dwarfs are on ultrashort-period and tidally locked orbits around white dwarf hosts. Because of these small orbital separations, the brown dwarfs are irradiated at levels similar to hot Jupiters. Yet, they are easier to observe than hot Jupiters because white dwarfs are fainter than main-sequence stars at near-infrared wavelengths. Irrad…
Prediction of Astrometric-microlensing Events from Gaia eDR3 Proper Motions
Bastian, Ulrich; Wambsganss, Joachim; Klüter, Jonas +1 more
Astrometric microlensing is a unique tool to measure stellar masses. It allows us to determine the mass of the lensing star with an accuracy of a few percent. In this paper, we update, extend, and refine our predictions of astrometric-microlensing events based on Gaia's early Data release 3 (eDR3). We selected about 500.000 high-proper-motion star…
The Chemical Composition of Extreme-velocity Stars
Hawkins, Keith; Frebel, Anna; Ji, Alexander P. +5 more
Little is known about the origin of the fastest stars in the Galaxy. Our understanding of the chemical evolution history of the Milky Way and surrounding dwarf galaxies allows us to use the chemical composition of a star to investigate its origin and to say whether it was formed in situ or was accreted. However, the fastest stars, the hypervelocit…