Search Publications
Dependence of Virial Factors on Optical Spectral Properties of Active Galactic Nuclei
Du, Pu; Wang, Jian-Min; Yang, Sen
Reverberation mapping (RM) has long been a powerful tool for measuring the masses of supermassive black holes (SMBHs) at the centers of active galactic nuclei (AGNs), but the precision of these mass measurements depends on the so-called virial factors. It has been demonstrated that the virial factors exhibit significant diversity, spanning approxi…
Every Data Point Counts: Stellar Flares as a Case Study of Atmosphere-aided Studies of Transients in the LSST Era
Davenport, James R. A.; Bosch, James; Graham, Melissa L. +9 more
Due to their short timescale, stellar flares are a challenging target for the most modern synoptic sky surveys. The upcoming Vera C. Rubin Legacy Survey of Space and Time (LSST), a project designed to collect more data than any precursor survey, is unlikely to detect flares with more than one data point in its main survey. We developed a methodolo…
USmorph: An Updated Framework of Automatic Classification of Galaxy Morphologies and Its Application to Galaxies in the COSMOS Field
Lin, Zesen; Zhang, Hongxin; Kong, Xu +9 more
Morphological classification conveys abundant information on the formation, evolution, and environment of galaxies. In this work, we refine a two-step galaxy morphological classification framework (USmorph), which employs a combination of unsupervised machine-learning and supervised machine-learning techniques, along with a self-consistent and rob…
The NuSTAR Serendipitous Survey: The 80 Month Catalog and Source Properties of the High-energy Emitting Active Galactic Nucleus and Quasar Population
Noirot, Gaël; Brandt, William N.; Aird, James +32 more
We present a catalog of hard X-ray serendipitous sources detected in the first 80 months of observations by the Nuclear Spectroscopic Telescope Array (NuSTAR). The NuSTAR serendipitous survey 80 month (NSS80) catalog has an unprecedented ∼62 Ms of effective exposure time over 894 unique fields (a factor of 3 increase over the 40 month catalog, NSS…
A Blueprint for the Milky Way's Stellar Populations. V. 3D Local Dust Extinction
Beers, Timothy C.; Chiti, Anirudh; An, Deokkeun
Using a grid of empirically calibrated synthetic spectra developed in our previous study, we construct an all-sky 3D extinction map from the large collection of low-resolution XP spectra in Gaia DR3. Along each line of sight, with an area ranging from 0.2 to 13.4 deg2, we determine both the reddening and metallicity of main-sequence sta…
Metallicities and Refined Stellar Parameters for 52 Cool Dwarfs with Transiting Planets and Planet Candidates
Mayo, Andrew W.; Schlieder, Joshua E.; Giacalone, Steven +8 more
We collected near-infrared spectra of 65 cool stars with the NASA Infrared Telescope Facility and analyzed them to calculate accurate metallicities and stellar parameters. The sample of 55 M dwarfs and 10 K dwarfs includes 25 systems with confirmed planets and 27 systems with planet candidates identified by the K2 and TESS missions. Three of the 2…
Reconstructing Intrinsic Stellar Noise with Stellar Atmospheric Parameters and Chromospheric Activity
Xiang, Maosheng; Bi, Shaolan; Li, Yaguang +9 more
Accurately characterizing the intrinsic stellar photometric noise induced by stellar astrophysics, such as stellar activity, granulation, and oscillations, is of crucial importance for detecting transiting exoplanets. In this study, we investigate the relation between the intrinsic stellar photometric noise, quantified by the Kepler combined diffe…
Observational Properties of 155 β Cephei Pulsating Variable Stars
Shi, Xiang-dong; Qian, Sheng-bang; Zhu, Li-ying +3 more
β Cephei pulsating variable (BCEP) stars are the most massive pulsating variable stars in the main sequence, exhibiting both p- and g-mode pulsations. In this study, we identified 155 BCEP stars or candidates using data from TESS and Gaia, of which 83 were first confirmed as BCEP stars. They have visual magnitudes ranging from 8 to 12 mag and effe…
The XMM-Newton Line Emission Analysis Program (X-LEAP). I. Emission-line Survey of O VII, O VIII, and Fe L-shell Transitions
Bregman, Joel N.; Liu, Jifeng; Qu, Zhijie +1 more
The XMM-Newton Line Emission Analysis Program (X-LEAP) is designed to study diffuse X-ray emissions from the Milky Way (MW) hot gas, as well as emissions from the foreground solar wind charge exchange (SWCX). This paper presents an all-sky survey of spectral feature intensities corresponding to the O VII, O VIII, and iron L-shell (Fe-L) emissions.…
The ZTF Source Classification Project. III. A Catalog of Variable Sources
Riddle, Reed; Szkody, Paula; Graham, Matthew J. +22 more
The classification of variable objects provides insight into a wide variety of astrophysics ranging from stellar interiors to galactic nuclei. The Zwicky Transient Facility (ZTF) provides time-series observations that record the variability of more than a billion sources. The scale of these data necessitates automated approaches to make a thorough…