A5062990866- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Space Exploration and Technology
- Pulsars and Gravitational Waves Research
- Spectroscopy and Laser Applications
- History and Developments in Astronomy
- Solar and Space Plasma Dynamics
Beijing Normal University
2016-2024
Centre National de la Recherche Scientifique
2019-2022
Institut de Recherche en Astrophysique et Planétologie
2019-2022
Université de Toulouse
2019-2022
Université Toulouse III - Paul Sabatier
2019-2020
Phase \RNum{2} of the LAMOST-{\sl Kepler/K}2 survey (LK-MRS), initiated in 2018, aims at collecting medium-resolution spectra ($R\sim7,500$; hereafter MRS) for more than $50,000$ stars with multiple visits ($\sim60$ epochs) over a period 5 years (2018 September to 2023 June). We selected 20 footprints distributed across {\sl Kepler} field and six K}2 campaigns, each plate containing number ranging from $\sim2,000$ $\sim 3,000$. During first year observations, LK-MRS has already collected...
Context. The rotation period of stars is an important parameter along with mass, radius, effective temperature. It essential for any radial velocity monitoring, as stellar activity can mimic the presence a planet at period. Several methods exist to measure it, including long sequences photometric measurements or temporal series indicators. Aims. Here, we use circular polarization in near-infrared spectral lines sample 43 quiet M dwarfs and compare measured periods those obtained other...
Stellar flares are critical phenomena on stellar surfaces, which closely tied to magnetism. While extensively studied in main-sequence (MS) stars, their occurrence evolved compact specifically hot subdwarfs and white dwarfs (WDs), remains scarcely explored. Based Cycles 1-5 of TESS photometry, we conducted a pioneering survey flare events $\sim12,000$ corresponding $\sim38,000$ light curves with 2-minute cadence. Through dedicated techniques for detrending curves, identifying preliminary...
Context. A new X-ray Cataclysmic variable (CV) candidate exhibits distinct light-curve characteristics in the ZTF’s g , r and i bands. The paper includes optical identification multiwavelength analysis of this CV candidate. Aims. This work aims to determine if a previously identified candidate, ZTF J0112+5827, is polar system by examining its cyclotron radiation characteristics. Methods. We characterized emission J0112+5827 using ROSAT observations. gri -band light curves were obtained from...
Context. Young solar analogs reaching the main sequence experience very strong magnetic activity, generating angular momentum losses through wind and mass ejections. Aims. We investigate signatures of fields activity at surface in prominence system ultra-rapid rotator V530 Per, a G-type solar-like member young open cluster α Persei. This object has rotation period that is shorter than all stars with available maps. Methods. With time-series spectropolarimetric observations gathered ESPaDOnS...
Aims. In this work we present the results of our analysis 16 300 medium-resolution LAMOST spectra late-type stars in Kepler field with aim determining stellar parameters, activity level, lithium atmospheric content, and binarity. Methods. We have used a version code rotfit specifically developed for lamost to determine parameters via adoption grid real stars. provide catalog ( T eff , log g [Fe/H]), radial velocity (RV), projected rotation v sin i ). For cool ≤ 6500 K), also calculated Ha Li...
Abstract Stellar flares are critical phenomena on stellar surfaces, which closely tied to magnetism. While extensively studied in main-sequence (MS) stars, their occurrence evolved compact specifically hot subdwarfs and white dwarfs (WDs), remains scarcely explored. Based Cycles 1–5 of TESS photometry, we conducted a pioneering survey flare events ∼12,000 corresponding ∼38,000 light curves with 2 minute cadence. Through dedicated techniques for detrending curves, identifying preliminary...
Aims. The very weak magnetic field detected at the surface of Vega hints a widespread population weakly stars A and B spectral types. We contribute here to gather more clues about origin this magnetism by investigating long-term stability geometry prototypical star. Methods. use spectropolarimetric data collected as part campaign, with than 2,000 observations spread between 2008 2018. Using various sub-sets extracted from whole time series, we reconstruct several maps large-scale field....
Abstract Homogeneous metallicities and continuous high-precision light curves play key roles in studying the pulsation properties of RR Lyrae stars. By cross matching LAMOST DR6 with Kepler K2 fields, we have determined seven 50 non-Blazhko RRab stars, respectively, that homogeneous from low-resolution spectra LAMOST–Kepler/K2 survey. The Fourier decomposition method is applied to these stars provided by space-based telescope determine fundamental periods parameters. calculated amplitude...
Aims: We investigate magnetic tracers in the photosphere and chromosphere of ultra-rapid rotator ($P\sim0.32d$) V530 Per, a cool member open cluster $\alpha$ Persei, to characterize short-term variability activity large-scale field this prototypical young, rapidly rotating solar-like star. Methods: With time-resolved spectropolarimetric observations spread over four close-by nights, we reconstructed brightness distribution geometry Per through Zeeman-Doppler imaging. Simultaneously,...
An increasing number of white dwarf stars shows atmospheric chemical composition polluted by heavy elements accreted from debris disc material. The existence such discs strongly suggests the presence one or more planet(s) whose gravitational interaction with rocky planetesimals is responsible for their disruption tidal effect. ZZ Ceti pulsator and DAZ GD 133 are good candidates searching a potential planet. We started in 2011 photometric follow-up its pulsations. As result this work...
Time-series, multi-color photometry and high-resolution spectra of the short period eclipsing binary V Tri were obtained by observations. The completely covered light radial velocity curves system are presented. All times minima derived from both photoelectric CCD used to calculate orbital new ephemerides system. analysis $O-C$ diagram reveals that is $0.58520481\ days$, decreasing at a rate $dP/dt=-7.80\times10^{-8} d\ yr^{-1} $. mass transfer between two components time-travel effect due...
Abstract Based on spectroscopic observations for the eclipsing binaries CSTAR 036162 and 055495 with WiFeS/2.3 m telescope at SSO 057775 Mage/Magellan I LCO in 2017, stellar parameters are derived. More than 100 nights of almost-continuous light curves reduced from time-series photometric by Dome A Antarctic i 2008 g r 2009, respectively, applied to find solutions three Wilson–Devinney code. The results show that is a detached configuration mass ratio q = 0.354 ± 0.0009, while semi-detached...
Context. Tidal deformation breaks the axisymmetric structure of stars, and this may affect stellar activity. This effect has been demonstrated in theoretical analyses simulations, but it lacks observational support. In paper, we use spot-modulated detached binaries to study tides on We show by analyzing properties spot lifetime, harmonic decay timescale, orbital parameters. Aims. aim explore differences lifetimes between single main mechanisms binaries, correlation parameters lifetimes....
KIC 10685175 is a roAp star whose polar magnetic field predicted to be 6 kG through non-adiabatic axisymmetric pulsation theoretical model. In this work, we aim measure the strength of using high-resolution spectropolarimetric observations, and compare it with one by From study two unpolarized spectra, obtained [$T_{\rm eff}$, $\log g$, [Fe/H], [$\alpha$/Fe], $V_{mic}$]=[8250 $\pm$ 200\,K, 4.4 0.1, -0.4 0.2, 0.16 1.73 0.2\,km~s$^{-1}$]. Although Fe absorption lines appear relatively weak in...
Abstract We present a comprehensive analysis of oscillations the helium-rich white dwarf DBV star EPIC 248705247 (SDSS J102106.69+082724.8). extract light curves from 79.7 days K2 Campaign 14 data and identify 21 independent frequencies, including three complete incomplete dipole modes, with an average frequency splitting 20.37 ± 0.40 μ Hz. Our analyses reveal rotation period approximately 6.82 0.07 hr, making it one most rapidly rotating stars currently known. utilize White Dwarf Evolution...
Context . KIC 10685175 is a roAp star whose polar magnetic field predicted to be 6 kG through nonadiabatic axisymmetric pulsation theoretical model. Aims In this work, we aim measure the strength of using high-resolution spectropolarimetric observations, and compare it with one by Methods Two unpolarized spectra have been analyzed ascertain presence magnetically split lines derive iron abundance equivalent width measurements 10 Fe lines. One polarized spectrum has used mean longitudinal...
This paper presents a photometric and spectroscopic study of the short-period binary star Cl*~Melotte~111~AV~1224. Measurements in $B$, $V$, $R$ passbands obtained during three observing runs between 2014 2017 medium-resolution spectra secured 2014, are analyzed together with public data from SuperWASP LAMOST projects. Our light curves show marked asymmetry variable O'Connell effect. The photometry is used to derive mean period 0.345225 days. analysis $(O-C)$ diagram reveals that orbital...
ABSTRACT New multicolour photometric observations were carried out on 22 nights in three observation missions between 2015 October and 2016 February for eclipsing binary HIP 7666. High- low-resolution spectroscopic also the winters of 2015, 2016, 2019, respectively. The fully phase-covered light curves radial velocity are presented. All times minima used to calculate orbital period [2.372 2200(4) d] new ephemerides. solution stellar physical parameters derived, showing that 7666 is a...
ROTSE1 J164341.65+251748.1 was photometrically observed in the V band during three epochs with 0.84-m telescope of San Pedro Mártir Observatory Mexico. Based on additional BVR photometry, we find that primary star has a spectral type around G0V. The light curve system is typical W~UMa binary stars and an orbital period $\sim$ 0.323 days. In effort to gain better understanding determine its physical properties, analyzed Wilson Devinney method. We found mass ratio 0.34 less massive component...
Abstract Young solar analogs reaching the main sequence experience very strong magnetic activity, directly linked to their angular momentum loss through wind and mass ejections. We investigate here surface chromospheric activity of ultra-rapid rotator AP 149 in young open cluster alpha Persei. With a time-series spectropolarimetric observations gathered over two nights with ESPaDOnS, we are able reconstruct distribution brightness field using Zeeman-Doppler-Imaging (ZDI) method. Using same...