Search Publications
NICMOS Kernel-phase Interferometry. II. Demographics of Nearby Brown Dwarfs
Kraus, Adam L.; Factor, Samuel M.
Star formation theories have struggled to reproduce binary brown dwarf population demographics (e.g., frequency, separation, and mass ratio). Kernel-phase interferometry is sensitive to companions at separations inaccessible to classical imaging, enabling tests of these theories at new physical scales below the hydrogen burning limit. We analyze t…
The Unexpected Optical and Ultraviolet Variability of the Standard Star α Sex (HD 87887)
Bowman, Dominic M.; Lebreton, Yveline; Monier, Richard +1 more
The analysis of the available Transiting Exoplanet Survey Satellite (TESS) light curves of α Sex (HD 87887) reveals low-frequency pulsations with a period of about 9.1 hr in this spectroscopic A0 III standard star. The IUE observations in 1992 December reveal large flux variations both in the far-UV and in the mid-UV, which are accompanied by vari…
The Wagging Plasma Tail of Comet C/2020 S3 (Erasmus)
Jewitt, David; Li, Jing; Kim, Yoonyoung
Long-period comet C/2020 S3 (Erasmus) reached perihelion at 0.398 au on UT 2020 December 12.67, making it a bright, near-Sun object. Images taken between 2020 mid-November and December using the HI-1 camera and COR2 coronagraph on board STEREO-A, as well as the LASCO/C3 coronagraph on board SoHO, show significant variations in the plasma tail posi…
Comprehensive Analysis of a Symbiotic Candidate V503 Her
Boussin, Christophe; Buil, Christian; Medulka, Tomáš +10 more
V503 Her was previously proposed as an eclipsing symbiotic candidate based on photometric behavior and spectroscopic appearance indicating the composite optical spectrum. To investigate its nature, we analyzed long-term photometric observations covering 100 yr of its photometric history and new low-resolution optical spectroscopic data, supplement…
Variability in Early Post-main-sequence Stars in Globular Cluster NGC 3201
Villanova, S.; Parisi, C.; Cortés, C. C. +3 more
In this paper we study stellar variability in the globular cluster NGC 3201 in the magnitude range V = 16-17, corresponding to the subgiant branch and blue stragglers region of the cluster. Our aim is to expand the sample of new type of variables with low amplitude and a short period found in previous papers. We used observations obtained at the C…
The Dependence of Iron-rich Metal-poor Star Occurrence on Galactic Environment Supports an Origin in Thermonuclear Supernova Nucleosynthesis
Reggiani, Henrique; Schlaufman, Kevin C.; Reeves, Zachary
It has been suggested that a class of chemically peculiar metal-poor stars called iron-rich metal-poor (IRMP) stars formed from molecular cores with metal contents dominated by thermonuclear supernova nucleosynthesis. If this interpretation is accurate, then IRMP stars should be more common in environments where thermonuclear supernovae were impor…
A Study of Eight Visual-spectroscopic Southern Binaries Using Recent SOAR Observations
Docobo, José A.; Campo, Pedro P.; Costa, Edgardo +2 more
Speckle observations performed between 2019 and 2022 with the HRCam attached to the 4.1 m SOAR telescope (Cerro Pachón, Chile) permitted to improve visual orbits of the southern binaries WDS 01243-0655 (BU 1163), WDS 09275-5806 (CHR 240), WDS 12114-1647 (S 643 AaAb), WDS 13317-0219 (HDS 1895), WDS 15282-0921 (BAG 25 AaAb), WDS 17304-0104 (STF 2173…
Optical Studies of Seven Bright Southern Cataclysmic Variable Stars
Thorstensen, John R.; Alvarado-Anderson, Chase K.; Burrows, Abigail D. +2 more
We report spectroscopic observations of seven bright southern cataclysmic variable stars, collected on a single two-week observing run using the 1.9 m Radcliffe telescope at the South African Astronomical Observatory. We used a radial-velocity time series, in some cases in combination with other data, to determine or clarify orbital periods for fi…
Physical Properties of the Young Asteroid Pair 2010 UM26 and 2010 RN221
Mutchler, Max; Jewitt, David; Li, Jing +1 more
The main belt asteroids 458271 (2010 UM26) and 2010 RN221 share almost identical orbital elements, and currently appear as comoving objects ~30″ apart in the plane of the sky. They are products of the breakup of a parent object, or the splitting of a binary, with a separation age measured in decades rather than thousands or millions of years as fo…
Empirical 2MASS-WFC3/IR Filter Transformations Across the H-R Diagram from Synthetic Photometry
Dalcanton, J. J.; Durbin, M. J.; Beaton, R. L. +2 more
Near-infrared bandpasses on spaceborne observatories diverge from their ground-based counterparts as they are free of atmospheric telluric absorption. Available transformations between respective filter systems in the literature rely on theoretical stellar atmospheres, which are known to have difficulties reproducing the observed spectral energy d…