Search Publications
ALMA Observations of the Asymmetric Dust Disk around DM Tau
Dong, Ruobing; Liu, Hauyu Baobab; Tsukagoshi, Takashi +5 more
We report an analysis of the dust disk around DM Tau, newly observed with the Atacama Large Millimeter/submillimeter Array (ALMA) at 1.3 mm. The ALMA observations with high sensitivity (8.4 µJy beam-1) and high angular resolution (35 mas, 5.1 au) detect two asymmetries on the ring at r ∼ 20 au. They could be two vortices in early …
The ALMA Survey of 70 µm Dark High-mass Clumps in Early Stages (ASHES). IV. Star Formation Signatures in G023.477
Jackson, James M.; Sanhueza, Patricio; Lu, Xing +15 more
With a mass of ~1000 M ⊙ and a surface density of ~0.5 g cm-2, G023.477+0.114, also known as IRDC 18310-4, is an infrared dark cloud (IRDC) that has the potential to form high-mass stars and has been recognized as a promising prestellar clump candidate. To characterize the early stages of high-mass star formation, we have obs…
The Red Supergiant Binary Fraction as a Function of Metallicity in M31 and M33
Neugent, Kathryn F.
Recent work measuring the binary fraction of evolved red supergiants (RSGs) in the Magellanic Clouds points to a value between 15% and 30%, with the majority of the companions being unevolved B-type stars as dictated by stellar evolution. Here I extend this research to the Local Group galaxies M31 and M33 and investigate the RSG binary fraction as…
The Age of Westerlund 1 Revisited
Smith, Nathan; Gehrz, Robert D.; Figer, Donald F. +2 more
The cluster Westerlund 1 (Wd1) is host to a large variety of post-main-sequence (MS) massive stars. The simultaneous presence of these stars can only be explained by stellar models if the cluster has a finely tuned age of 4-5 Myr, with several published studies independently claiming ages within this range. At this age, stellar models predict that…
Distant Relatives: The Chemical Homogeneity of Comoving Pairs Identified in Gaia
Ting, Yuan-Sen; Hawkins, Keith; El-Badry, Kareem +3 more
Comoving pairs, even at the separations of ${ \mathcal O }({10}^{6})$ au, are a predicted reservoir of conatal stars. We present detailed chemical abundances of 62 stars in 31 comoving pairs with separations of 102-107 au and 3D velocity differences <2 km s-1. This sample includes both bound comoving pairs/wide …
NGC 5128 Globular Cluster Candidates Out to 150 kpc: A Comprehensive Catalog from Gaia and Ground-based Data
Forbes, Duncan A.; Caldwell, Nelson; Strader, Jay +9 more
We present a new catalog of 40,502 globular cluster (GC) candidates in NGC 5128 out to a projected radius of ~150 kpc based on data from the Panoramic Imaging Survey of Centaurus and Sculptor, the Gaia Data Release 2, and the NOAO Source Catalog. Ranking these candidates based on the likelihood that they are true GCs, we find that approximately 19…
Observations of Magnetic Fields Surrounding LkHα 101 Taken by the BISTRO Survey with JCMT-POL-2
Zhang, Yapeng; Pattle, Kate; Ward-Thompson, Derek +146 more
We report the first high spatial resolution measurement of magnetic fields surrounding LkHα 101, part of the Auriga-California molecular cloud. The observations were taken with the POL-2 polarimeter on the James Clerk Maxwell Telescope within the framework of the B-fields In Star-forming Region Observations (BISTRO) survey. Observed polarization o…
Extensive Lensing Survey of Optical and Near-infrared Dark Objects (El Sonido): HST H-faint Galaxies behind 101 Lensing Clusters
Pérez-González, Pablo G.; Koekemoer, Anton M.; Smail, Ian +22 more
We present a Spitzer/IRAC survey of H-faint (H 160 ≳ 26.4, < 5σ) sources in 101 lensing cluster fields. Across a CANDELS/Wide-like survey area of ~648 arcmin2 (effectively ~221 arcmin2 in the source plane), we have securely discovered 53 sources in the IRAC Channel-2 band (CH2, 4.5 µm; median CH2 = 22.46 ±…
Detection of Flare Multiperiodic Pulsations in Mid-ultraviolet Balmer Continuum, Lyα, Hard X-Ray, and Radio Emissions Simultaneously
Li, Gang; Gan, Weiqun; Li, Xiaobo +7 more
Quasi-periodic pulsations (QPPs), which usually appear as temporal pulsations of the total flux, are frequently detected in the light curves of solar/stellar flares. In this study, we present the investigation of nonstationary QPPs with multiple periods during the impulsive phase of a powerful flare on 2017 September 6, which were simultaneously m…
Testing Evolutionary Models with Red Supergiant and Wolf-Rayet Populations
Massey, Philip; Dorn-Wallenstein, Trevor Z.; Levesque, Emily M. +3 more
Despite the many successes that modern massive star evolutionary theory has enjoyed, reproducing the apparent trend in the relative number of red supergiants (RSGs) and Wolf-Rayet (WR) stars has remained elusive. Previous estimates show the RSG/WR ratio decreasing strongly with increasing metallicity. However, the evolutionary models have always p…