Search Publications
Correction to the Photometric Colors of Gaia Early Data Release 3
Niu, Zexi; Liu, Jifeng; Yuan, Haibo
In this work, we use the spectroscopy-based stellar color regression method with ∼0.7 million common stars between LAMOST DR7 and Gaia EDR3 to acquire color corrections in G - GRP and GBP - GRP. A sub-millimagnitude precision is achieved. Our results demonstrate that improvements in the calibration process of the E…
Spiral Arm Pattern Motion in the SAO 206462 Protoplanetary Disk
Dong, Ruobing; Pueyo, Laurent; Stolker, Tomas +5 more
Spiral arms have been observed in more than a dozen protoplanetary disks, yet the origin of nearly all systems is under debate. Multi-epoch monitoring of spiral arm morphology offers a dynamical way to distinguish two leading arm formation mechanisms: companion-driven and gravitational instability induction, since these mechanisms predict distinct…
Multiple Stellar Populations in Asymptotic Giant Branch Stars of Galactic Globular Clusters
Milone, A. P.; Cordoni, G.; Marino, A. F. +8 more
Multiple stellar populations (MPs) are a distinct characteristic of globular clusters (GCs). Their general properties have been widely studied among main-sequence, red giant branch (RGB), and horizontal branch (HB) stars, but a common framework is still missing at later evolutionary stages. We studied the MP phenomenon along the asymptotic giant b…
The Late-time Radio Behavior of Gamma-ray Burst Afterglows: Testing the Standard Model
Fruchter, Andrew S.; Kangas, Tuomas
We examine a sample of 21 gamma-ray burst (GRB) afterglow light curves at radio frequencies and compare them to the X-ray and/or optical properties of the afterglows and to the predictions of the standard jet/fireball model. Our sample includes every Swift GRB with an X-ray light curve indicating a jet break and with a published radio light curve,…
A Near-infrared Survey of UV-excited Molecular Hydrogen in Photodissociation Regions
Kim, Hwihyun; Dinerstein, Harriet L.; Jaffe, Daniel T. +1 more
We present a comparative study of the near-infrared (NIR) H2 line emission from five regions near hot young stars: Sharpless 140, NGC 2023, IC 63, the Horsehead Nebula, and the Orion Bar. This emission originates in photodissociation or photon-dominated regions (PDRs), interfaces between photoionized and molecular gas near hot (O) stars…
The Be Star 66 Ophiuchi: 60 Years of Disk Evolution
Carciofi, A. C.; Mota, B. C.; Jones, C. E. +5 more
We use a time-dependent hydrodynamic code and a non-LTE Monte Carlo code to model disk dissipation for the Be star 66 Ophiuchi. We compiled 63 years of observations from 1957 to 2020 to encompass the complete history of the growth and subsequent dissipation of the star's disk. Our models are constrained by new and archival photometry, spectroscopy…
Caltech-NRAO Stripe 82 Survey (CNSS). V. AGNs That Transitioned to Radio-loud State
Gromadzki, Mariusz; Hallinan, Gregg; Ishwara-Chandra, C. H. +6 more
A recent multiyear Caltech-NRAO Stripe 82 Survey revealed a group of objects that appeared as new radio sources after >5-20 yr of absence. They are transient phenomena with respect to the Faint Images of the Radio Sky at Twenty Centimeters survey and constitute the first unbiased sample of renewed radio activity. Here we present a follow-up, ra…
Hybrid Comptonization and Electron-Positron Pair Production in the Black-hole X-Ray Binary MAXI J1820+070
Poutanen, Juri; Zdziarski, Andrzej A.; Szanecki, Michał +6 more
We study X-ray and soft gamma-ray spectra from the hard state of the accreting black-hole binary MAXI J1820+070. We perform an analysis of two joint spectra from NuSTAR and INTEGRAL, covering the range of 3-650 keV, and of an average joint spectrum over the rise of the hard state, covering the 3-2200 keV range. The spectra are well modeled by Comp…
Dynamical Analysis of the Dark Matter and Central Black Hole Mass in the Dwarf Spheroidal Leo I
Gebhardt, Karl; Zeimann, Greg; Thomas, Jens +4 more
We measure the central kinematics for the dwarf spheroidal galaxy Leo I using integrated-light measurements and previously published data. We find a steady rise in the velocity dispersion from 300″ into the center. The integrated-light kinematics provide a velocity dispersion of 11.76 ± 0.66 km s-1 inside 75″. After applying appropriate…
A Blueprint for the Milky Way's Stellar Populations. III. Spatial Distributions and Population Fractions of Local Halo Stars
Beers, Timothy C.; An, Deokkeun
We analyze the observed spatial, chemical and dynamical distributions of local metal-poor stars, based on photometrically derived metallicity and distance estimates along with proper motions from the Gaia mission. Along the Galactic prime meridian, we identify stellar populations with distinct properties in the metallicity versus rotational veloci…