相关论文: Variability in NGC 3201 giant stars and its impact…

We present a catalog of 417 luminous infrared variable stars with periods exceeding 250 days. These were identified in 20 nearby galaxies by the ongoing SPIRITS survey with the Spitzer Space Telescope. Of these, 359 variables have…

We describe here results of a photometric time-sequence survey of the globular cluster M3 (NGC 5272), in a search for contact and detached eclipsing binary stars. We have discovered only one likely eclipsing binary and one SX Phe type star…

Very metal-poor stars are of obvious importance for many problems in chemical evolution, star formation, and galaxy evolution. Finding complete samples of such stars which are also bright enough to allow high-precision individual analyses…

Building on previous work, we have expanded our catalog of evolutionary models for stars with variable composition; here we present models for stars of mass 0.5 - 1.2 Msol, at scaled metallicities of 0.1 - 1.5 Zsol, and specific C/Fe,…

Images recorded with the Gemini Multi-Object Spectrograph (GMOS) on Gemini South are combined with archival images from other facilities to search for variable stars in the southern portion of the nearby disk galaxy NGC 247. Fifteen new…

We present the analysis of high-resolution spectra obtained with UVES and UVES-FLAMES at the Very Large Telescope of 17 giants in the globular cluster M22, a stellar system suspected to have an intrinsic spread in the iron abundance. We…

The goal of our study is to provide a reliable classification of variability of A-F stars brighter than 11 mag located in the northern TESS continuous viewing zone. We also aim at thorough discussion about issues in the classification…

We report the first abundance analysis of 17 M giant stars in the inner Galactic bulge at $(l,b)=(0\deg,-1\deg)$, based on $R=25,000$ infrared spectroscopy $(1.5-1.8 ~\mu \rm m)$ using NIRSPEC at the Keck telescope. Based on their…

The variability of optical FeII blends in NGC 4051 is examined from spectra extracted from the AGN Watch program.In our analysis, the FeII complex are subtracted and measured with the following results. Firstly, the FeII variations were…

We present results of time series photometry to search for variable stars in the field of metal-poor globular cluster NGC 4590 (M68). Periods have been revised for 40 known variables and no significant changes were found. A considerable…

Using data from the (intermediate) Palomar Transient Factory (iPTF), we characterize the time variability of ~500 massive stars in M31. Our sample is those stars which are spectrally typed by Massey and collaborators, including Luminous…

We present the results of an intensive photometric and spectroscopic monitoring campaign of the WN4 Wolf-Rayet (WR) star WR1=HD4004. Our broadband V photometry covering a timespan of 91 days shows variability with a period of…

Evolutionary trends in the surface abundances of heavier elements have recently been identified in the globular cluster NGC 6397 ([Fe/H]=-2), indicating the operation of atomic diffusion in these stars. Such trends constitute important…

The well-known correlation between stellar metallicity and planet occurrence is strongest for giant planets, but weaker for smaller planets, suggesting that detailed elemental patterns beyond [Fe/H] may be relevant. Using abundances from…

We determine the iron distribution function (IDF) for bulge field stars, in three different fields along the Galactic minor axis and at latitudes b=-4 deg, b=-6 deg, and b=-12 deg. A fourth field including NGC6553 is also included in the…

We present a study of accurate stellar parameters and iron abundances for 39 giants and 16 dwarfs in the 13 open clusters IC2714, IC4651, IC4756, NGC2360, NGC2423, NGC2447 (M93), NGC2539, NGC2682 (M67), NGC3114, NGC3680, NGC4349, NGC5822,…

NGC5824 is a massive Galactic globular cluster suspected to have an intrinsic spread in its iron content, according to the strength of the calcium triplet lines. We present chemical abundances of 117 cluster giant stars using…

We report time-series photometry for 16 variable stars located in the central part of the globular cluster NGC 6752. The sample includes 13 newly identified objects. The precision of our differential photometry ranges from 1 mmag at V=14.0…

We present the iron abundance and abundance ratios for 18 elements with respect to Fe in a sample of stars with a wide range in luminosity from luminous giants to stars near the turnoff in the globular cluster M5. The analyzed spectra,…

Multiple populations are ubiquitous in the old massive globular clusters (GCs) of the Milky Way. It is still unclear how they arose during the formation of a GC. The topic of iron and metallicity variations has recently attracted attention…