- ID:
- ivo://CDS.VizieR/J/A+A/576/A66
- Title:
- BD+20 1790 radial velocities and photometry
- Short Name:
- J/A+A/576/A66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In a previous paper we reported a planetary companion to the young and very active K5Ve star BD+20 1790. This paper aims to more rigorously assess the nature of the radial velocity measurements with an expanded data set and new methods of analysis. We have employed Bayesian methods to simultaneously analyse the radial velocity and activity measurements based on a combined data set that includes new and previously published observations.
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Search Results
- ID:
- ivo://CDS.VizieR/J/other/Nat/594.365
- Title:
- Betelgeuse during its Great Dimming
- Short Name:
- J/other/Nat/594.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Red supergiants represent the most common final stage of the evolution of stars with initial masses between 8 and 30-35 times the mass of the Sun. During this phase of lifetime ~10^5 yrs, they experience substantial mass loss of unknown mechanism (Arroyo-Torres et al., 2015A&A...575A..50A). This mass loss can affect their evolutionary path, collapse, future supernova light curve, and ultimate fate as a neutron star or a black hole. From November 2019 to March 2020, the second closest red supergiant (RSG, 222^+48^_-34_pc) Betelgeuse experienced a historic dimming of its visible brightness, witnessed worldwide. Usually between 0.1 and 1.0mag, it went down to 1.614+/-0.008mag around 7-13 February 2020. Here we report high angular resolution observations showing that the southern hemisphere of the star was ten times darker than usual in the visible. Observations and modeling support the scenario of a dust clump recently formed in the vicinity of the star due to a local temperature decrease in a cool patch appearing on the photosphere. The directly imaged brightness variations of Betelgeuse evolved on a timescale of weeks. This event suggests that an inhomogeneous component of red supergiant mass loss is linked to a very contrasted and rapidly changing photosphere.
- ID:
- ivo://CDS.VizieR/J/PASP/110/533
- Title:
- BR photometry of Fornax bright stars
- Short Name:
- J/PASP/110/533
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present accurate photometry on the Johnson B, Kron-Cousins R photometric system for approximately 100,000 stars in a 1/3deg^2^ field centered on the dwarf spheroidal galaxy in Fornax. We identify numerous probable short-period variable stars, blue stars that appear to be the main sequence of a small population with an age of order 108yr, and two distinct types of luminous red star: an extended sequence of primarily carbon stars and a clump of mostly M giants slightly more luminous than the giant-branch tip. The spatial distribution of each of these subpopulations within the Fornax dwarf galaxy is considered.
- ID:
- ivo://CDS.VizieR/J/A+A/402/1033
- Title:
- BV photometry of UX Ari in 1987-2002
- Short Name:
- J/A+A/402/1033
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 14.3 years of previously unpublished photometric observations of UX Ari. The observations were obtained between 1987.9 and 2002.2 using the T3 0.4-metre Automatic Photoelectric Telescope at Fairborn Observatory and consist of 1228 B band and 1213 V band measurements. The comparison star was 62 Ari and the check star was 59 Ari. We have analyzed the new data together with previously published photometric observations. The V magnitude shows variations with dominant periods of about 12 and 25 years, where the longest period seems to correspond to an activity cycle. The previously reported anticorrelation between the B V colour and V magnitude variations is confirmed.
- ID:
- ivo://CDS.VizieR/J/MNRAS/289/729
- Title:
- BVRIJHK photometry of red LMC supergiants
- Short Name:
- J/MNRAS/289/729
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (BV)_J_(RI)_C_ observations for 185 and additional JHK observations for 53 red supergiant candidates in the Large Magellanic Cloud (LMC) are presented. The data have been reduced discussing carefully the dependence of effective wavelengths on the spectral energy distribution of the star, which is very strong especially for the Cousins R band. Non-linear colour dependences of transformation coefficients vor the V magnitude and the R-I colour have been taken into account. The mean error of the BVRI data is 0.03 to 0.04 mag, while that of the JHK observations is 0.02mag. The MK types are not given to the stars, as the classifications given in the literature are mostly very uncertain. The spectra we have obtained for 88 of the stars will be discussed in a forthcoming paper where we will give directly physical properties like Mbol and Teff instead of MK types. Most of the stars are supergiants of type late K to early M.
- ID:
- ivo://CDS.VizieR/J/other/NewA/17.46
- Title:
- BVR light curves of V1191 Cyg
- Short Name:
- J/other/NewA/17.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the analysis of photometric and spectroscopic variation, and orbital period study of the late-type contact binary system V1191 Cyg. The system is found to be a contact binary system having strange configuration with very small mass ratio and short orbital period comparing with the other members of the same group. We determined a new set of stellar physical parameters for hot and cooler companion as M_h_=0.13(1)M_{sun}_, M_c_=1.29(8)M_{sun}_, R_h_=0.52(15)R_{sun}_, R_c_=1.31(18)R_{sun}_, L_h_=0.46(25)L_{sun}_, L_c_=2.71(80)L_{sun}_, and the separation between the components a=2.20(8)R_{sun}_ from the simultaneous solution of the light and radial velocity curves. Analyses of the mid-eclipses time of the system indicate a period increase of dP/dt=1.3(1)x10^-6^days/yr that can be interpreted in terms of the high mass transfer dM/dt=2.0(4)x10^-7^M_{sun}_/yr from the less massive component to the more massive one.
- ID:
- ivo://CDS.VizieR/J/A+A/177/131
- Title:
- CaII and MgII excess flux density in cool stars
- Short Name:
- J/A+A/177/131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The relation between the CaII H and K line-tore flux density and rotation period is studied for a sample of 313 cool stars of luminosity classes ranging from II-III to V, and compared to similar relations for MgII h and k and soft X-ray.
- ID:
- ivo://CDS.VizieR/J/MNRAS/426/1591
- Title:
- CaII equivalent widths of dM1 stars
- Short Name:
- J/MNRAS/426/1591
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 187 high-resolution spectra for 62 different M1 dwarfs from observations obtained with the FIbre-fed Echelle Spectrograph (FIES) on the Nordic Optical Telescope (NOT) and from observations with the Fibre-fed Extended Range Echelle Spectrograph (FEROS) from the European Southern Observatory (ESO) data base. We also compiled other measurements available in the literature.
- ID:
- ivo://CDS.VizieR/J/PASP/111/335
- Title:
- CaII-M_v_ Correlation (Wilson-Bappu Effect)
- Short Name:
- J/PASP/111/335
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Hipparcos parallaxes were used to derive absolute visual magnitudes of G, K, and M stars with Ca II emission line widths previously measured by O.C. Wilson. A linear relationship similar to the one derived originally by Wilson & Bappu and improved by Lutz & Kelker was found from M_v_=+7 to -2. For stars brighter than M_v_=-2 a substantial number of stars show Ca II emission lines that are broader than expected from the linear fit. Most of those stars are bright giants and supergiants of type G.
- ID:
- ivo://CDS.VizieR/J/A+AS/124/359
- Title:
- Ca II triplet lines in cool stars
- Short Name:
- J/A+AS/124/359
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD spectra of the infrared triplet lines of ionized calcium at {lambda}{lambda}8498, 8542, 8662 have been obtained at a spectral resolution of 0.4{AA} in 146 stars brighter than V=+7.0 spanning a range in spectral types from F7 to M4 of all luminosity classes and a range in metallicity [Fe/H] from -3.0 to +1.1. These have been analysed to investigate the dependence of the Ca II triplet strengths on stellar parameters like luminosity, temperature and metallicity. A detailed study reveals a strong dependence on luminosity, much stronger for metal rich stars than for the metal poor ones and a milder dependence on metallicity, although much more conspicuous in supergiants than in dwarfs. All these correlations are found to be non-linear over the parameter space covered. The present study also shows chromospheric activity to be an important phenomenon affecting the strength and the shape of the line profiles. Stars of similar luminosity and metallicity have varying Ca II line depths owing to varying chromospheric emission filling in their Ca II absorption. The Ca II triplet strength is thus observed to be a triparametric discriminant in cool stars.
