Search Publications
Age Determination of LAMOST Red Giant Branch Stars Based on the Gradient Boosting Decision Tree Method
Deng, Li-Cai; Chen, Li; Spina, Lorenzo +5 more
In this study, we estimate the stellar ages of LAMOST DR8 red giant branch (RGB) stars based on the gradient boosting decision tree (GBDT) algorithm. We used 2643 RGB stars extracted from the APOKASC-2 asteroseismological catalog as the training data set. After selecting the parameters ([α/Fe], [C/Fe], T eff, [N/Fe], [C/H], log g) highl…
Multiple Emission Lines of Hα Emitters at z ∼ 2.3 from the Broad- and Medium-band Photometry in the ZFOURGE Survey
Momose, Rieko; Kodama, Tadayuki; Nakajima, Kimihiko +8 more
We present a multiple emission line study of ∼1300 Hα emitters (HAEs) at z ∼ 2.3 in the ZFOURGE survey. In contrast to the traditional spectroscopic method, our sample is selected based on the flux excess in the ZFOURGE K s broadband data relative to the best-fit stellar continuum. Using the same method, we also extract the strong dia…
Constraining Stellar Rotation at the Zero-age Main Sequence with TESS
Huang, C. X.; Wright, N. J.; Zhou, G. +5 more
The zero-age main sequence (ZAMS) is a critical phase for stellar angular momentum evolution, as stars transition from contraction-dominated spin-up to magnetic wind-dominated spin-down. We present the first robust observational constraints on rotation for FGK stars at ≈40 Myr. We have analyzed TESS light curves for 1410 members of five young open…
The Disappearance of the Blue and Luminous Progenitor of the Type IIn SN 2010jl
Niu, Zexi; Sun, Ning-Chen; Liu, Jifeng
Type IIn supernovae (SNe) exhibit narrow hydrogen lines that arise from the strong interaction between ejecta and circumstellar material. It remains poorly understood, however, what progenitor stars give rise to these explosions. In this work, we perform a detailed analysis of the progenitor and environment of the nearby Type IIn SN 2010jl. With n…
The Role of Spiral Arms in Galaxies
Calzetti, Daniela; Battisti, Andrew J.; Sun, Bingqing
We test the influence of spiral arms on the star formation activity of disk galaxies by constructing and fitting multiwavelength spectral energy distributions for the two nearby spiral galaxies NGC 628 and NGC 4321, at a spatial scale of 1–1.5 kpc. Recent results in the literature support the "gatherers" picture, i.e., that spiral arms gather mate…
Four-hundred Very Metal-poor Stars Studied with LAMOST and Subaru. III. Dynamically Tagged Groups and Chemodynamical Properties
Shi, Jianrong; Zhao, Gang; Chen, Yuqin +9 more
Very metal-poor (VMP) stars record the signatures of early accreted galaxies, making them essential tools for unraveling the early stages of Galaxy formation. Understanding the origin of VMP stars requires comprehensive studies of their chemical compositions and kinematics, which are currently lacking. Hence, we conduct a chemodynamical analysis o…
Age of Massive Galaxies at Redshift 8
López-Corredoira, M.; Melia, F.; Wei, J. -J. +1 more
Recent James Webb Space Telescope data analyses have shown that massive red galaxies existed at redshifts z ≳ 6, a discovery that is difficult to understand in the context of standard cosmology (ΛCDM). Here, we analyze these observations more deeply, by fitting a stellar population model to the optical and near-infrared photometric data. These fit…
Deep Chandra Observation of the Remarkable Ionization Cones of NGC 5252
Elvis, Martin; Guainazzi, Matteo; Bianchi, Stefano +4 more
Seyfert galaxy NGC 5252 harbors enormously extended ionization cones that have been previously detected in the optical and X-ray band, offering a unique opportunity to investigate the interaction between the central active galactic nucleus (AGN) and the surrounding gas in the AGN host galaxy. We present deep Chandra imaging spectroscopy of NGC 525…
JWST-FEAST: Feedback in Emerging extrAgalactic Star clusTers: Calibration of Star Formation Rates in the Mid-infrared with NGC 628
Östlin, Göran; Smith, Linda J.; Melinder, Jens +19 more
New JWST near-infrared imaging of the nearby galaxy NGC 628 from the JWST Cycle 1 program Feedback in Emerging extrAgalactic Star clusTers (JWST-FEAST) is combined with archival JWST mid-infrared imaging to calibrate the 21 µm emission as a star formation rate (SFR) indicator at ∼120 pc scales. The Paα (1.8756 µm) hydrogen recombinatio…
X-Ray Characterization of the Pulsar PSR J1849-0001 and Its Wind Nebula G32.64+0.53 Associated with TeV Sources Detected by H.E.S.S., HAWC, Tibet ASγ, and LHAASO
Woo, Jooyun; An, Hongjun; Mori, Kaya +6 more
We report on the X-ray emission properties of the pulsar PSR J1849-0001 and its wind nebula (PWN), as measured by Chandra, XMM-Newton, NICER, Swift, and NuSTAR. In the X-ray data, we detected the 38 ms pulsations of the pulsar up to ~60 keV with high significance. Additionally, we found that the pulsar's on-pulse spectral energy distribution displ…