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 Physalis system: discovery of ORC-like radio shells around a massive pair of interacting early-type galaxies with offset X-ray emission
Koribalski, Bärbel S.; Khabibullin, Ildar; Dolag, Klaus +7 more
We present the discovery of large radio shells around a massive pair of interacting galaxies and extended diffuse X-ray emission within the shells. The radio data were obtained with the Australian Square Kilometre Array Pathfinder (ASKAP) in two frequency bands centred at 944 MHz and 1.4 GHz, respectively, while the X-ray data are from the XMM-New…
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…
Full orbital solutions in pre-main sequence high-order multiple systems: GG Tau Ab and UX Tau B
Duchêne, Gaspard; Ménard, François; Langlois, Maud +3 more
Context. High-order multiple (triple and beyond) systems are relatively common. Their interaction with circumstellar and circumbinary material can have a large impact on the formation and evolution of planetary systems and depends on their orbital properties.
Aims: GG Tau and UX Tau are two pre-main sequence high-order multiple systems in whi…
A Data-driven Search For Mid-infrared Excesses Among Five Million Main-sequence FGK Stars
Hogg, David W.; Contardo, Gabriella
Stellar infrared excesses can indicate various phenomena of interest, from protoplanetary disks to debris disks, or (more speculatively) techno-signatures along the lines of Dyson spheres. In this paper, we conduct a large search for "extreme" infrared excesses, designed as a data-driven contextual anomaly detection pipeline. We focus our search o…
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…