8 papers
A Uniform Census of Variable Stars in M101 Based on HST/ACS Photometry
Jiyu Wang, Xiaodian Chen, Pinjian Chen +3
We present a homogeneous HST/ACS F555W/F814W time-series census of variable stars in two M101 disk fields, using a uniform multi-band reduction and reproducible variable-selection…
A Stable Mineral Fingerprint in the Fading Warm Debris Disk around HD 15407A
Shu Wang, Zhuochao Huang, Xiaodian Chen +2
Extreme debris disks provide time-domain probes of rocky planet assembly after giant impacts. We compare Spitzer and JWST spectra of the warm debris disk around HD 15407A, obtained…
Divergent Evolution of Radial Metallicity Gradients in the Thin and Thick Disks of the Milky Way
Weixiang Sun, Gaohuan Long, Hui Li +6
Using 200,388 red clump stars from LAMOST and APOGEE, we investigate the radial metallicity gradients of the Galactic disk as a function of vertical height and stellar age. The thi…
Distance-Ladder Measurements of the Hubble Constant: Recent Progress, Systematics, and Prospects
Xiaodian Chen, Shu Wang
The Hubble constant, \(H_0\), links the nearby distance scale to the present cosmic expansion rate. Local distance-ladder measurements now reach percent-level precision and remain…
A Planetary Nebula from a 5.7 Progenitor in a 90 Myr M31 Star Cluster
Pinjian Chen, Bingqiu Chen, Xiaodian Chen +2
Planetary nebulae (PNe) trace the late evolution of low-to-intermediate-mass stars, yet the masses of their progenitors are rarely measured directly. Here we present a PN physicall…
Discovery of an Extremely Luminous Type II Cepheid in the Andromeda Giant Stellar Stream: Evidence for a Hierarchical Triple with an Inner Binary Merger
Pinjian Chen, Bingqiu Chen, Xiaodian Chen +7
We report the discovery of LAMOST J0041+3948, the most luminous post-AGB Type II Cepheid (TIIC) known, located in the Andromeda Giant Stellar Stream. Its spectral energy distributi…
A Massive Yellow Supergiant in the Far Outer Disk of M31: Evidence for In Situ Massive Star Formation Beyond the Optical Radius
Pinjian Chen, Bingqiu Chen, Haibo Yuan +5
While massive stars are known to shape galactic ecosystems, their formation has long been assumed to require the high-density environments of inner galactic disks. This paradigm is…
Investigating the Period-Luminosity Relations of delta Scuti Stars: A Pathway to Distance and 3-D Dust Map Inference
Fangzhou Guo, Joshua S. Bloom, Xiaofeng Wang +12
While delta Scuti stars are the most numerous class of kappa-mechanism pulsators in the instability strip, the short periods and small peak-to-peak amplitudes have left them unders…