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A Study of Nine Extremely Low Mass Ratio-contact Binary Systems
Ferreira Lopes, C. E.; Catelan, Márcio; Lalounta, Eleni +2 more
Low-mass ratio systems (LMR) are a very interesting class of contact eclipsing binaries challenging the theoretical models of stability. These systems are also considered possible progenitors of the rare low-mass optical transients called red novae. In this study, we present the identification of 7 new totally eclipsing LMR systems from Catalina S…
Scalable, Advanced Machine Learning Based Approaches for Stellar Flare Identification: Application to TESS Short-cadence Data and Analysis of a New Flare Catalog
Apai, Dániel; Lin, Chia-Lung; Giampapa, Mark S. +1 more
We apply multialgorithm machine learning models to TESS 2 minute survey data from Sectors 1–72 to identify stellar flares. Models trained with deep neural network, random forest, and XGBoost algorithms utilize four flare light-curve characteristics as input features. Model performance is evaluated using the accuracy, precision, recall, and F …
The POKEMON Speckle Survey of Nearby M Dwarfs. III. The Stellar Multiplicity Rate of M Dwarfs within 15 pc
Skiff, Brian A.; Hartman, Zachary D.; Ciardi, David R. +8 more
M dwarfs are ubiquitous in our Galaxy, and the rate at which they host stellar companions, and the properties of these companions, provide a window into the formation and evolution of the star(s), and of any planets that they may host. The Pervasive Overview of "Kompanions" of Every M dwarf in Our Neighborhood (POKEMON) speckle survey of nearby M …
The TESS-Keck Survey. XVIII. A Sub-Neptune and Spurious Long-period Signal in the TOI-1751 System
Kostov, Veselin B.; Bieryla, Allyson; Mayo, Andrew W. +37 more
We present and confirm TOI-1751 b, a transiting sub-Neptune orbiting a slightly evolved, solar-type, metal-poor star (T eff = 5996 ± 110 K, $\mathrm{log}(g)=4.2\pm 0.1$ , V = 9.3 mag, [Fe/H] = ‑0.40 ± 0.06 dex) every 37.47 days. We use TESS photometry to measure a planet radius of ${2.77}_{-0.07}^{+0.15}\,{R}_{\oplus }$ . We also use bo…
Speckle Interferometry at SOAR Telescope in 2023
Tokovinin, Andrei; Mason, Brian D.; Mendez, Rene A. +1 more
Results of the speckle-interferometry observations at the 4.1 m Southern Astrophysical Research Telescope obtained during 2023 are presented: 1913 measurements of 1533 resolved pairs or subsystems (median separation 0.″16) and nonresolutions of 552 targets; 42 pairs are resolved here for the first time. This work continues our long-term effort to …
An Absolute Mass, Precise Age, and Hints of Planetary Winds for WASP-121A and b from a JWST NIRSpec Phase Curve
Sing, David K.; Lothringer, Joshua D.; Rustamkulov, Zafar +3 more
We have conducted a planetary radial velocity measurement of the ultrahot Jupiter WASP-121b using JWST NIRSpec phase curve data. Our analysis reveals the Doppler shift of the planetary spectral lines across the full orbit, which shifts considerably across the detector (∼10 pixels). Using cross-correlation techniques, we have determined an overall …
A Testbed for Tidal Migration: The 3D Architecture of an Eccentric Hot Jupiter HD 118203 b Accompanied by a Possibly Aligned Outer Giant Planet
Huber, Daniel; Claytor, Zachary R.; Saunders, Nicholas +32 more
Characterizing outer companions to hot Jupiters plays a crucial role in deciphering their origins. We present the discovery of a long-period giant planet, HD 118203 c (
The Emerging Stellar Complex in Mon R2: Membership and Optical Variability Classification
Hillenbrand, Lynne A.; Jiang, Sally D.
Monoceros R2 (Mon R2) is one of the closest large active star-forming regions. This extremely young and partially embedded region provides an excellent laboratory for studying star formation and the early evolution of young stellar objects (YSOs). In this paper, we conduct an optical study of the greater Mon R2 region. Beginning with 1690 previous…
Magnetic Fields in the Southern Coalsack and Beyond
Magalhães, A. M.; Kawabata, Koji S.; Rodrigues, C. V. +4 more
Starlight polarimetry, when combined with accurate distance measurements, allows for exploration of the three-dimensional structure of local magnetic fields in great detail. We present optical polarimetric observations of stars in and close to the Southern Coalsack, taken from the Interstellar Polarization Survey. Located in five fields of view ap…
Velocity Dispersion of the Open Cluster NGC 2571 by Radial Velocities and Proper Motions
Carraro, Giovanni; Seleznev, Anton F.; Kulesh, Maxim V. +3 more
We use a kernel density estimator method to evaluate the stellar velocity dispersion in the open cluster NGC 2571. We derive the 3D velocity dispersion using both proper motions as extracted from Gaia Data Release 3 and single-epoch radial velocities as obtained with the instrument FLAMES at ESO's Very Large Telescope. The mean-square velocity alo…