Search Publications
The Detection of a Hot Molecular Core in the Extreme Outer Galaxy
Shimonishi, Takashi; Furuya, Kenji; Izumi, Natsuko +1 more
Interstellar chemistry in low-metallicity environments is crucial to understand chemical processes in the past metal-poor universe. Recent studies of interstellar molecules in nearby low-metallicity galaxies have suggested that metallicity has a significant effect on the chemistry of star-forming cores. Here we report the first detection of a hot …
Big Three Dragons: A [N II] 122 µm Constraint and New Dust-continuum Detection of a z = 7.15 Bright Lyman-break Galaxy with ALMA
Fujimoto, Seiji; Inoue, Akio K.; Hashimoto, Takuya +6 more
We present new Atacama Large Millimeter/submillimeter Array Band 7 observational results of a Lyman-break galaxy at z = 7.15, B14-65666 ("Big Three Dragons"), which is an object detected in [O III] 88 µm, [C II] 158 µm, and dust continuum emission during the epoch of reionization. Our targets are the [N II] 122 µm fine-structure …
Red Supergiants in M31 and M33. I. The Complete Sample
Yang, Ming; Ren, Yi; Jiang, Biwei +3 more
The aim of this paper is to establish a complete sample of red supergiants (RSGs) in M31 and M33. The member stars of the two galaxies are selected from the near-infrared (NIR) point sources after removing the foreground dwarfs from their obvious branch in the J - H/H - K diagram with the archival photometric data taken by the UKIRT/WFCAM. This se…
Planets Across Space and Time (PAST). I. Characterizing the Memberships of Galactic Components and Stellar Ages: Revisiting the Kinematic Methods and Applying to Planet Host Stars
Huang, Yang; Dong, Subo; Liu, Chao +7 more
Over 4000 exoplanets have been identified and thousands of candidates are to be confirmed. The relations between the characteristics of these planetary systems and the kinematics, Galactic components, and ages of their host stars have yet to be well explored. To address these questions, we conduct a research project, dubbed Planets Across Space an…
Most "Young" α-rich Stars Have High Masses but are Actually Old
Xiang, Maosheng; Huang, Yang; Ting, Yuan-Sen +8 more
Recent observations have revealed a population of α-element abundances, enhanced giant stars with unexpected high masses (≳1 M ⊙) from asteroseismic analysis and spectroscopy. Assuming single-star evolution, their masses imply young ages (τ < 6 Gyr) incompatible with the canonical Galactic chemical evolution scenario. Here we study t…
VVV CL001: Likely the Most Metal-poor Surviving Globular Cluster in the Inner Galaxy
Majewski, Steven R.; Beers, Timothy C.; Minniti, Dante +11 more
We present the first high-resolution abundance analysis of the globular cluster VVV CL001, which resides in a region dominated by high interstellar reddening toward the Galactic bulge. Using H-band spectra acquired by the Apache Point Observatory Galactic Evolution Experiment, we identified two potential members of the cluster, and estimated from …
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…