相关论文: GALEX J184559.8-413827: a new extreme helium star …

We present a quantitative spectroscopic and kinematic analysis of a volume-complete sample of hot subluminous stars within 500 pc of the Sun, assembled using accurate parallax measurements from Gaia Data Release 3 (DR3). In total, 3226…

Observations of the HBL blazar 1RXS J023832.6-311658 were made in 2013, 2015 and 2016 with the High Energy Stereoscopic System (H.E.S.S.). An excess of very high energy (VHE: > 100 GeV) gamma rays is clearly observed. The spectral energy…

HESS J1745-303 is an extended, unidentified VHE (very high energy) gamma-ray source discovered using HESS in the Galactic Plane Survey. Since no obvious counterpart has previously been found in longer-wavelength data, the processes that…

Subluminous B stars come in a variety of flavours including single stars, close and wide binaries, and pulsating and non-pulsating variables. A majority have helium-poor surfaces (helium by number nHe<1%), whilst a minority have extremely…

We analyze the spectrum of an unusually-low mass white dwarf, SDSSJ123410.37-022802.9 (0335-264-52000), found in our recent, white dwarf catalog from the SDSS DR1 data release. Two independent, model atmosphere fits result in an accurate…

Precise proper motion measurements (sigma_mu ~ 10 mkas/yr) of the recently discovered hyper-velocity star (HVS) SDSS J090745.0+024507 would yield significant constraints on the axis ratios and orientation of a triaxial model for the…

The intermediate Helium subdwarf B star LS IV$-$14$^\circ$116 is a unique object showing extremely peculiar atmospheric abundances as well as long-period pulsations that cannot be explained in terms of the usual opacity mechanism. One…

We present a follow-up study on the recent detection of two X-ray flaring events by MAXI/GSC observations in soft and hard X-rays from MAXI J0709-159 in the direction of HD 54786 (LY CMa), on 2022 January 25. The X-ray luminosity during the…

In the line-of-sight toward the DO-type white dwarf RX J0503.9-2854, the density of the interstellar medium (ISM) is very low, and thus the contamination of the stellar spectrum almost negligible. This allows us to identify many metal lines…

Stars with very large mass loss on the red-giant branch can undergo the helium flash while descending the white-dwarf cooling curve. Under these conditions the flash convection zone will mix the hydrogen envelope with the hot helium-…

We have used the ACS and WFC3 cameras on board HST to resolve stars in the halo of the nearest giant elliptical (gE) galaxy NGC 5128 out to a projected distance of 140 kpc (25 effective radii, Reff) along the major axis and 90 kpc (16 Reff)…

We present the first observations of hydrogen line emission detected around the B-type star HD 46487, a well-studied star in the CoRoT field of view. The emission is only evident in the H$\alpha$ line, for which the observed violet-red peak…

182 single-lined hot subdwarf stars are identified by using spectra from the sixth and seventh data release (DR6 and DR7) of the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) survey. We classified all the hot subdwarf…

We report the analysis of optical spectra of the extreme helium star LSS 3184 (BX Cir) to determine its effective temperature and gravity throughout its pulsation cycle. The spectra were also used to measure its chemical abundances. We…

PG1159 stars are hot, hydrogen-deficient (pre-) white dwarfs with atmospheres mainly composed of helium, carbon, and oxygen. The unusual surface chemistry is the result of a late helium-shell flash. Observed element abundances enable us to…

We used ultra-deep observations obtained with the NIRCam aboard the James Webb Space Telescope to explore the stellar population of NGC 6440: a typical massive, obscured and contaminated globular cluster formed and orbiting within the…

We present a detailed study of a unusually bright, lensed galaxy at $z=5.424$ discovered within the CFHTLS imaging survey. With an observed flux of $i_{\rm AB}=23.0$, J141446.82+544631.9 is one of the brightest galaxies known at $z>5$. It…

The star CD-42o11721 is a curious B[e] star sometimes pointed as an evolved B[e] supergiant and sometimes as a young HAeBe star, due to very uncertain or even unknown stellar parameters, especially the distance. In this paper, we present…

We report the discovery of HE 0430-2457, the first extremely low-mass pre-white dwarf (ELM pre-WD) in a long period binary (P = 771 +- 3 d). The spectroscopic parameters of the primary are determined to be Teff = 26200 +- 1500 K and logg =…

Hot subluminous stars lying up to 0.7 mag below the extreme horizontal branch (EHB) are found in the UV color-magnitude diagrams of omega Cen and NGC 2808. Such stars are unexplained by canonical HB theory. In order to explore the origin of…