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We develop a new and powerful method to analyze time series to rigorously detect flares in the presence of an irregularly oscillatory baseline, and apply it to stellar light curves observed with TESS. First, we remove the underlying…

Solar and Stellar Astrophysics · Physics 2025-12-23 Qiyuan Wang , Giovanni Motta , Genaro Sucarrat , Vinay L. Kashyap

The number of known periodic variable stars has increased rapidly in recent years. As an all-sky transit survey, the Transiting Exoplanet Survey Satellite (TESS) plays an important role in detecting low-amplitude variable stars. Using…

Solar and Stellar Astrophysics · Physics 2024-12-10 Xinyi Gao , Xiaodian Chen , Shu Wang , Jifeng Liu

We present a synopsis of the project to establish thirty-two new faint ($ 16.5 \leq V \leq 19.8 $) DA white dwarfs as spectrophotometric standards distributed over the whole sky. Our results validate the use of fully radiative pure hydrogen…

During its 2-year Prime Mission, TESS observed over 232,000 stars at a 2-min cadence across ~70% of the sky. These data provide a record of photometric variability across a range of astrophysically interesting time scales, probing stellar…

The inferred effective temperatures (T$_{\rm eff}$) and surface gravities of T Tauri stars (TTS) are usually contaminated by the presence of a non stellar continuum emission (veiling) and the strong chromospheric activity characteristic of…

Astrophysics · Physics 2016-08-30 R. Piorno Schiavon , C. Batalha , B. Barbuy

We present the selection and classification of over a thousand ultraviolet (UV) variable sources discovered in ~ 40 deg^2 of GALEX Time Domain Survey (TDS) NUV images observed with a cadence of 2 days and a baseline of observations of ~ 3…

The Gaia mission has delivered hundreds of thousands of variable star light curves in multiple wavelengths. Recent work demonstrates that these light curves can be used to identify (non-)radial pulsations in the OBAF-type stars, despite the…

Solar and Stellar Astrophysics · Physics 2024-08-14 Daniel Hey , Conny Aerts

The DAV star, HS0507+0434B, was observed by Fu et al. (2013) in 2007 and from 2009 December to 2010 January. There were a total of six triplets with nearly equal split, which were identified as $l$ = 1 modes caused by rotation. In order to…

Solar and Stellar Astrophysics · Physics 2016-04-12 YanHui Chen , Yan Li

Using transient grating spectroscopy (TGS) we measure the thermal diffusivity of tungsten exposed to different levels of 20 MeV self-ion irradiation. Damage as low as 3.2 x 10^-4 displacements per atom (dpa) causes a measurable reduction in…

Materials Science · Physics 2020-02-05 Abdallah Reza , Hongbing Yu , Kenichiro Mizohata , Felix Hofmann

Context: the theory of stellar evolution presents shortcomings when confronted with asteroseismic probes of interior physical properties. The differences between observations and theory are often great because stellar models have mainly…

Solar and Stellar Astrophysics · Physics 2022-06-29 S. Garcia , T. Van Reeth , J. De Ridder , A. Tkachenko , L. IJspeert , C. Aerts

The collections of spectral energy distributions (SEDs) in the \emph{Hubble Space Telescope} (HST) CALSPEC database are augmented by 19 IR SEDs from Wide Field Camera 3 (WFC3) IR grism spectra. Together, the two IR grisms, G102 and G141,…

Instrumentation and Methods for Astrophysics · Physics 2019-03-29 Ralph C. Bohlin , Susana E. Deustua

We have analyzed GHRS data of eight Classical T Tauri stars (CTTSs) and one Weak T Tauri star (WTTS). The GHRS data consist of an spectral range 40 A wide centered on 2800 A. For 4 of the CTTS we have nearly simultaneous optical…

Classical T Tauri stars (CTTS) exhibit strong variability over timescales of minutes to decades. However, much theoretical work assumes that CTTS are in stable spin states. Here, we test expectations for CTTS angular momentum regulation by…

We reinvestigate the question of spatial variation of the local D/H abundance, using both archival GHRS spectra, and new echelle spectra of G191-B2B obtained with the Space Telescope Imaging Spectrograph (STIS) aboard HST. Our analysis uses…

The IR emission of dust heated by stars provides critical information for galaxy evolution studies. Unfortunately, observations are often limited to the MIR, making templates a necessity. Previously published templates were based on small…

Astrophysics of Galaxies · Physics 2021-10-04 Médéric Boquien , Samir Salim

We present a unified experiment, analysis, and benchmark study of multivariate time-series (MTS) anomaly detection. Ten family-representative detectors -- spanning statistical, reconstruction, association, frequency, and generic-transformer…

Machine Learning · Computer Science 2026-05-28 Junhao Wei , Yanxiao Li , Bidong Chen , Yifu Zhao , Haochen Li , Dexing Yao , Baili Lu , Xudong Ye , Jietian Feng , Sio-Kei Im , Yapeng Wang , Xu Yang

We present analysis of the starspot properties and chromospheric activity on HD 134319 using high precision photometry by TESS in sectors 14-16 (T1), 21-23 (T2) and high-resolution spectroscopy by OHP/ELODIE and Keck/HIRES during years…

Solar and Stellar Astrophysics · Physics 2022-06-29 Fukun Xu , Shenghong Gu , Panogiotis Ioannidis

We aim to detect and characterise solar-like oscillations in bright naked-eye (V<6) main-sequence (MS) and subgiant stars observed by TESS. We seek to expand the current benchmark sample of oscillators, provide accurate global asteroseismic…

Hot subdwarf B (sdB) stars are post-main-sequence stars of high temperature and gravity. Approximately 30$\%$ of sdBs exhibit stable pressure and/or gravity-mode pulsations, which can be used via the timing method to test for companion…

Solar and Stellar Astrophysics · Physics 2025-08-05 Tomomi Otani , A. S. Baran , Lindsay C. Spence , Ted von Hippel , E. Lynum-Lozano , Julia. M. Clark

We have observed again two stars inside the ZZ Ceti instability strip that were previously classified as not-observed-to-vary (NOV) by Mukadam et al. (2004) and found them to be low-amplitude variables. Some evidence points to a pure ZZ…