Search Publications
Roaring to Softly Whispering: X-Ray Emission after ∼3.7 yr at the Location of the Transient AT2018cow and Implications for Accretion-powered Scenarios
Berger, E.; Vignali, C.; Maccarone, T. +11 more
We present the first deep X-ray observations of luminous fast blue optical transient (LFBOT) AT 2018cow at ∼3.7 yr since discovery, together with the reanalysis of the observation at δ t ∼ 220 days. X-ray emission is significantly detected at a location consistent with AT 2018cow. The very soft X-ray spectrum and sustained luminosity are distinct …
Stellar Loci. VII. Photometric Metallicities of 5 Million FGK Stars Based on GALEX GR6+7 AIS and Gaia EDR3
Huang, Yang; Beers, Timothy C.; Yuan, Haibo +5 more
We combine photometric data from GALEX GR6+7 All-Sky Imaging Survey and Gaia Early Data Release 3 with stellar parameters from the SAGA and PASTEL catalogs to construct high-quality training samples for dwarfs (0.4 < BP ‑ RP < 1.6) and giants (0.6 < BP ‑ RP < 1.6). We apply careful reddening corrections using empirical temperature- and…
Mining the GALAH Data. I. Study of Five Super Lithium-rich Metal-poor Giants
Reddy, Bacham E.; Susmitha, Antony; Mallick, Anohita
The presence of a large amount of Li in giants is still a mystery. Most of the super Li-rich (SLR) giants reported in recent studies are in the solar metallicity regime. Here, we study the five metal-poor SLRs from the Galactic Archeology with HERMES Data Release 3, with their [Fe/H] ranging from ‑1.35 to ‑2.38 with lithium abundance of A(Li) ≥ 3.…
Rotational Evolution of Classical T Tauri Stars: Models and Observations
Pinsonneault, Marc; Stassun, Keivan G.; Kounkel, Marina +17 more
We developed a grid of stellar rotation models for low-mass and solar-type classical T Tauri stars (CTTS; 0.3M ⊙ < M * < 1.2M ⊙). These models incorporate the star–disk interaction and magnetospheric ejections to investigate the evolution of the stellar rotation rate as a function of the mass of the star M
Ring Gap Structure around Class I Protostar WL 17
Shoshi, Ayumu; Harada, Naoto; Tokuda, Kazuki +7 more
WL 17 is a Class I object and was considered to have a ring–hole structure. We analyzed the structure around WL 17 to investigate the detailed properties of this object. We used Atacama Large Millimeter/submillimeter Array archival data, which have a higher angular resolution than previous observations. We investigated the WL 17 system with the 1.…
High-energy spectra of LTT 1445A and GJ 486 reveal flares and activity
France, K.; Buchhave, L. A.; Kreidberg, L. +19 more
The high-energy radiative output, from the X-ray to the ultraviolet, of exoplanet host stars drives photochemical reactions and mass loss in the upper regions of planetary atmospheres. In order to place constraints on the atmospheric properties of the three closest terrestrial exoplanets transiting M dwarfs, we observe the high-energy spectra of t…
A MIRI Search for Planets and Dust around WD 2149+021
Barclay, Thomas; Hermes, J. J.; Reach, William T. +9 more
The launch of JWST has ushered in a new era of high-precision infrared astronomy, allowing us to probe nearby white dwarfs for cold dust, exoplanets, and tidally heated exomoons. While previous searches for these exoplanets have successfully ruled out companions as small as 7–10 Jupiter masses (M Jup), no instrument prior to JWST has be…
Accurate and Model-independent Radius Determination of Single FGK and M Dwarfs Using Gaia DR3 Data
Kiman, Rocio; Faherty, Jacqueline K.; Brandt, Timothy D. +1 more
Measuring fundamental stellar parameters is key to fully comprehending the evolution of stars. However, current theoretical models overpredict effective temperatures, and underpredict radii, compared to observations of K and M dwarfs (radius inflation problem). In this work, we have developed a model-independent method to infer precise radii of si…
KMT-2023-BLG-2669: Ninth Free-floating Planet Candidate with θ E Measurements
Han, Cheongho; Lee, Chung-Uk; Zang, Weicheng +17 more
We report a free-floating planet (FFP) candidate identified from the analysis of the microlensing event KMT-2023-BLG-2669. The lensing light curve is characterized by a short duration (≲3 days) and a small amplitude (≲0.7 mag). From the analysis, we find an Einstein timescale of t E ⋍ 0.33 days and an Einstein radius of θ E ⋍…
Properties of the gas escaping from a non-isothermal porous dust surface layer of a comet
Mottola, S.; Küppers, M.; Thomas, N. +6 more
Estimation of the properties of the sublimation products leaving the cometary nucleus is one of the significant questions in the study of the dusty-gas flow following the Rosetta mission. It is widely assumed that the temperature of the water molecules emitted is the temperature of ice directly exposed to the surface. However, it is the simplest n…