Search Publications
Massive Quiescent Disk Galaxies at 0.5 ≤ z ≤ 1 in CANDELS: Color Gradients and Likely Origin
Cui, Qifan; Liu, F. S.; Zhao, Pinsong
A rare population of massive disk-dominated quiescent galaxies has recently drawn much attention, which intrudes the red sequence (RS) population without destroying the underlying stellar disks. In this study, we have carefully identified 48 RS, disk-dominated galaxies with M * > 1010 M ⊙ between redshift 0.5 an…
Period–Luminosity–Metallicity–Color Relations of Late-type Contact Binaries in the Big Data Era
Tian, Zhi-Jia; Song, Lian-Yun
Binary stars ubiquitous throughout the Universe are important. Contact binaries (CBs) possessing period–luminosity (PL) relations could be adopted as distance tracers. The PL relations of CBs are influenced by metallicity abundance and color index, which are connected to both the radius and luminosity of stars. Here we propose fine relations of th…
A New Cosmic-Ray Rejection Routine for HST WFC3/UVIS via Label-free Training of deepCR
Williams, Benjamin F.; Zhang, Keming; Durbin, Meredith +1 more
deepCR is a deep-learning-based cosmic-ray (CR) rejection framework originally presented by Zhang & Bloom. The original approach requires a dedicated training set that consists of multiple frames of the same fields, enabling automatic CR labeling through comparison with their median coadds. Here, we present a novel training approach that circu…
CHARA Near-infrared Imaging of the Yellow Hypergiant Star ρ Cassiopeiae: Convection Cells and Circumstellar Envelope
Gies, Douglas R.; Monnier, John D.; Schaefer, Gail H. +18 more
Massive evolved stars such as red supergiants and hypergiants are potential progenitors of Type II supernovae, and they are known for ejecting substantial amounts of matter, up to half their initial mass, during their final evolutionary phases. The rate and mechanism of this mass loss play a crucial role in determining their ultimate fate and the …
DESI Massive Poststarburst Galaxies at z ∼ 1.2 Have Compact Structures and Dense Cores
Miquel, Ramon; Sanchez, Eusebio; Bezanson, Rachel +34 more
Poststarburst galaxies (PSBs) are young quiescent galaxies that have recently experienced a rapid decrease in star formation, allowing us to probe the fast-quenching period of galaxy evolution. In this work, we obtained Hubble Space Telescope (HST)/WFC3 F110W imaging to measure the sizes of 171 massive (
Integrated Study of X-Ray Spectrum and Time Lags for HBL Mrk 421 within the Framework of the Multiple-zone Leptonic Model
Xiao, Guang-Cheng; Hu, Wen; Kang, Jia-Lai +3 more
We present the timing analysis of 10 archived XMM-Newton observations with an exposure of >40 ks of Markarian 421. Mrk 421 is the brightest high-frequency-peaked BL Lac object emitting in X-rays produced by electrons accelerated in the innermost regions of a relativistic jet pointing toward us. For each observation, we construct averaged X-ray …
Efficiency of Nonthermal Pulsed Emission from Eight MeV Pulsars
Takata, J.; Wang, H. -H.; Lin, L. C. -C., +1 more
We report on the properties of pulsed X-ray emission from eight MeV pulsars using XMM-Newton, NICER, NuSTAR, and HXMT data. For five of the eight MeV pulsars, the X-ray spectra can be fit by a broken power-law model with a break energy of ∼5–10 keV. The photon indices below and above the break energy are ∼1 and ∼1.5, respectively. In comparison wi…
Spatial Variations and Breaks in the Optical–Near-infrared Spectra of the Pulsar and Pulsar Wind Nebula in Supernova Remnant 0540–69.3
Tenhu, L.; Larsson, J.; Sollerman, J. +4 more
The supernova remnant (SNR) 0540–69.3, twin of the Crab Nebula, offers an excellent opportunity to study the continuum emission from a young pulsar and pulsar wind nebula (PWN). We present observations taken with the Very Large Telescope instruments MUSE and X-shooter in the wavelength range 3000–25000 Å, which allow us to study spatial variations…
Probing Populations of Dark Stellar Remnants in the Globular Clusters 47 Tuc and Terzan 5 Using Pulsar Timing
Baumgardt, Holger; Smith, Peter J.; Hénault-Brunet, Vincent +2 more
We present a new method to combine multimass equilibrium dynamical models and pulsar timing data to constrain the mass distribution and remnant populations of Milky Way globular clusters (GCs). We first apply this method to 47 Tuc, a cluster for which there exists an abundance of stellar kinematic data and which is also host to a large population …
Discovery of a Barium Blue Straggler Star in M67 and "Sighting" of Its White Dwarf Companion
Jadhav, Vikrant V.; Reddy, Arumalla B. S.; Subramaniam, Annapurni +1 more
We report the discovery of a barium blue straggler star (BSS) in M67, exhibiting enhancements in slow neutron-capture (s-)process elements. Spectroscopic analysis of two BSSs (WOCS 9005 & WOCS 1020) and four stars located near the main-sequence turn-off using GALAH spectra, showed that WOCS 9005 has a significantly high abundance of the s-proc…