Boquan Chen

Star ages with ML and GALAH DR3 spectra

Hayden M.R, Sanjib Sharma, Joss Bland‐Hawthorn, L. Spina et autres

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The dawn is quiet II: Gaia XP constraints on the Milky Way’s proto-Galaxy from very metal-poor MDF tails

Boquan Chen, Matthew D A Orkney, Yuan-Sen Ting, Michael R. Hayden

The earliest phase of the Milky Way’s evolution involved a transition from a dispersion-supported proto-galaxy to a rotationally supported disk. A key chemical signature of this transition is the moderate rise in [ α /Fe] near [ F e / H ] …

The GALAH survey: Data release 4

Sven Buder, Janez Kos, Xi Ella Wang, Madeleine McKenzie et autres

The stars of the Milky Way carry the chemical history of our Galaxy in their atmospheres as they journey through its vast expanse. Like barcodes, we can extract the chemical fingerprints of stars from high-resolution spectroscopy. The fourth data release (DR4) of …

C3PO – IV. Co-natal stars depleted in refractories are magnetically more active – possible imprints of planets

Jie Yu, Yuan-Sen Ting, L. Casagrande, Fan Liu et autres

ABSTRACT Chemical abundance anomalies in twin stars have recently been considered tell-tale signs of interactions between stars and planets. While such signals are prevalent, their nature remains a subject of debate. On the one hand, exoplanet formation may induce chemical depletion in …

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C3PO IV: co-natal stars depleted in refractories are magnetically more active -- possible imprints of planets

Jie Yu, Yuan-Sen Ting, L. Casagrande, Fan Liu et autres

Chemical abundance anomalies in twin stars have recently been considered tell-tale signs of interactions between stars and planets. While such signals are prevalent, their nature remains a subject of debate. On one hand, exoplanet formation may induce chemical depletion in host stars …

Discovery of A Starburst in the Early Milky Way at [Fe/H] $< -2$

Boquan Chen, Matthew D A Orkney, Yuan-Sen Ting, Michael Hayden

We present an analysis of very metal-poor (VMP) and metal-poor stars ($-3.0 < \mathrm{Fe/H]} < -1.5$) in the Gaia BP/RP or XP catalog, which reveals two distinct metallicity distribution functions (MDFs) in regions of the Galactic disk above and below $|z| = …

The GALAH survey: Data release 4

Sven Buder, Janez Kos, Xinghuan Wang, Madeleine McKenzie et autres

Abstract The stars of the Milky Way carry the chemical history of our Galaxy in their atmospheres as they journey through its vast expanse. Like barcodes, we can extract the chemical fingerprints of stars from high-resolution spectroscopy. The fourth data release (DR4) …

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A Data-Assisted and Inter-Symbol Spectrum Analysis-Based Speed Estimation Method for Radiated Signals from Moving Sources

Gaohui Liu, Boquan Chen

Aiming at the problem of estimating the speed of M-ary Phase Shift Keying (MPSK) communication radiated sources and their carrying platform targets, this paper proposes a data-assisted and inter-symbol spectrum analysis-based speed estimation method for MPSK communication radiated sources. The method first …

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New evidence of binarity in young α-rich turn-off and subgiant stars: fast rotation and strong magnetic activity

Jie Yu, L. Casagrande, Ioana Ciucă, Yuan-Sen Ting et autres

ABSTRACT Young α-rich (YAR) stars within the old Galactic thick disc exhibit a dual characteristic of relative youth determined with asteroseismology and abundance enhancement in α elements measured from high-resolution spectroscopy. The youth origin of YAR stars has been proposed to be …

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New Evidence of Binarity in Young α-Rich Turn-off and Subgiant Stars: Fast Rotation and Strong Magnetic Activity

Jie Yu, L. Casagrande, Ioana Ciucă, Yuan-Sen Ting et autres

Young α-rich (YAR) stars within the old Galactic thick disk exhibit a dual characteristic of relative youth determined with asteroseismology and abundance enhancement in α elements measured from high-resolution spectroscopy. The youth origin of YAR stars has been proposed to be binary …

The dawn is quiet here: Rise in [ $\alpha$ /Fe] is a signature of massive gas accretion that fueled the proto-Milky Way

Boquan Chen, Yuan-Sen Ting, Michael Hayden

Abstract The proto-Milky Way epoch forms the earliest stars in our galaxy and sets the initial conditions for the subsequent disk formation. Recent observations showed that the [ $\alpha$ /Fe] ratio among in situ metal-poor stars declined between [Fe/H] $=-3$ and $-1.3$ …

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The dawn is quiet here: Rise in [$α$/Fe] is a signature of massive gas accretion that fueled proto-Milky Way

Boquan Chen, Yuan-Sen Ting, Michael Hayden

The proto-Milky Way epoch forms the earliest stars in our Galaxy and sets the initial conditions for subsequent disk formation. Recent observations from APOGEE and H3 surveys showed that the [$α$/Fe] ratio slowly declined between [Fe/H] $=-3$ and $-1.3$ until it reached …