- ID:
- ivo://CDS.VizieR/III/266
- Title:
- Revised First Byurakan Survey of late-type stars
- Short Name:
- III/266
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Between 1990 and 2010, 15 lists of late-type stars found in the low-dispersion spectroscopic plates of the First Byurakan Survey (FBS) were published. The systematic search and selection was carried out on a surface of 16000 sq.deg. on almost the whole area of the FBS. As a result, a comprehensive catalogue of the late-type stars of the FBS was generated. Its preliminary version has been available at the CDS since 2007 (Cat. III/246). We have revised and updated the FBS catalogue of late-type stars with new data from recently published optical and multiwavelength catalogues to give access to all available data and to make further comparative studies of the properties of these objects possible. We have made cross-correlations with the Digitized First Byurakan Survey (DFBS, Cat. VI/116)), the United States Naval Observatory-B1.0 catalogue (Cat. I/284), the Guide Star Catalogue 2.3.2 (Cat. I/305), Tycho-2 (Cat. I/259), Sloan Digital Sky Survey Data Release 8 (Cat. II/306), the Two-Micron All-Sky Survey (2MASS, Cat. II/246)), the Wide-field Infrared Survey Explorer catalogue (WISE, Cat. II/311), the Infrared Astronomical Satellite Point Source Catalogue/Faint Source Catalogue (IRAS Catalogs II/125, II/156), the AKARI catalogue (Cat. II/297), the ROSAT Bright Source Catalogue (IX/10) and Faint Source (IX/29) Catalogues, the General Catalogue of Variable Stars (B/gcvs) and the Northern Sky Variability Survey. Also, we have added updated SIMBAD data for the objects. We present accurate Digitized Sky Survey 2 positions, approximate spectral subtypes refined from the DFBS low-dispersion spectra, luminosity classes estimated from 2MASS colours and available proper motions for 1045 FBS late-type stars. The FBS revised and updated catalogue lists a large number of completely new objects, which promise to extend very significantly the census of M giants, faint carbon stars at high Galactic latitudes and M dwarfs in the vicinity of the Sun. We study the complete samples, as well as investigating individual interesting objects up to 16.0-16.5mag in visual.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/403/993
- Title:
- Revised HIP periods for long-period variables
- Short Name:
- J/A+A/403/993
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse the K-band luminosities of a sample of galactic long-period variables using parallaxes measured by the Hipparcos mission. The parallaxes are in most cases re-computed from the Hipparcos Intermediate Astrometric Data using improved astrometric fits and chromaticity corrections. The K band magnitudes are taken from the literature and from measurements by COBE, and are corrected for interstellar and circumstellar extinction. The sample contains stars of several spectral types: M, S and C, and of several variability classes: Mira, semiregular SRa, and SRb. We find that the distribution of stars in the period-luminosity plane is independent of circumstellar chemistry, but that the different variability types have different P-L distributions. Both the Mira variables and the SRb variables have reasonably well-defined period-luminosity relationships, but with very different slopes. The SRa variables are distributed between the two classes, suggesting that they are a mixture of Miras and SRb, rather than a separate class of stars. New period-luminosity relationships are derived based on our revised Hipparcos parallaxes. The Miras show a similar period-luminosity relationship to that found for Large Magellanic Cloud Miras by Feast et al. (1989MNRAS.241..375F).
- ID:
- ivo://CDS.VizieR/J/A+A/402/113
- Title:
- (RI)c photometry of variables in M31
- Short Name:
- J/A+A/402/113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Cousins R and I band photometry of variable stars in a ~13'x13' region in the disk of M31 galaxy, obtained during 141 nights. Of the 26 Cepheid variables present in the region, two are newly discovered, 11 are classified as Cepheids for the first time and 13 are confirmed as Cepheids. The extensive photometry of these Cepheids enabled us to determine precise phase and amplitude of pulsation which ranges from 0.11 to 0.48mag in R band. The period of variability ranges from ~7.5 to 56 days. The period-luminosity diagram is used to derive a distance modulus of 24.49+/-0.11mag for M31 galaxy. We also report variability in 333 other stars, of them, 115 stars appear to be long period variables, 2 suspected eclipsing binaries and remaining 216 are irregular variables.
- ID:
- ivo://CDS.VizieR/J/A+A/509/A17
- Title:
- R light curves of NGC 6253 variables
- Short Name:
- J/A+A/509/A17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This work presents the first high-precision variability survey in the field of the intermediate-age, metal-rich open cluster NGC 6253. We discovered 595 variables and we also characterized most of them providing their variability classes, periods and amplitudes. The sample is complete at short periods: we classified 20 pulsating variables, 225 contact systems, 99 eclipsing systems (22 Beta Lyr type, 59 Beta Per type, 18 RS CVn type), and 77 rotational variables. The time-baseline hampered the precise characterization of 173 variables with periods longer than 4-5days. Moreover, we found a cataclysmic system undergoing an outburst of about 2.5mag.
1135. RMC143 ALMA images
- ID:
- ivo://CDS.VizieR/J/A+A/626/A126
- Title:
- RMC143 ALMA images
- Short Name:
- J/A+A/626/A126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The luminous blue variable (LBV) RMC143 is located in the outskirts of the 30~Doradus complex, a region rich with interstellar material and hot luminous stars. We report the 3{sigma} sub-millimetre detection of its circumstellar nebula with ALMA. The observed morphology in the sub-millimetre is different than previously observed with HST and ATCA in the optical and centimetre wavelength regimes. The spectral energy distribution (SED) of RMC suggests that two emission mechanisms contribute to the sub-mm emission: optically thin bremsstrahlung and dust. Both the extinction map and the SED are consistent with a dusty massive nebula with a dust mass of 0.055+/-0.018M_{sun}_ (assuming {kappa}_850_=1.7cm^2^/g). To date, RMC143 has the most dusty LBV nebula observed in the Magellanic Clouds. We have also re-examined the LBV classification of RMC143 based on VLT/X-shooter spectra obtained in 2015/16 and a review of the publication record. The radiative transfer code CMFGEN is used to derive its fundamental stellar parameters. We find an effective temperature of ~8500K, luminosity of log(L/L_{sun}_)=5.32, and a relatively high mass-loss rate of 1.0x10^-5^M_{sun}_/yr. The luminosity is much lower than previously thought, which implies that the current stellar mass of ~8M_{sun}_ is comparable to its nebular mass of ~5.5~M_{sun}_ (from an assumed gas-to-dust ratio of 100), suggesting that the star has lost a large fraction of its initial mass in past LBV eruptions or binary interactions. While the star may have been hotter in the past, it is currently not hot enough to ionize its circumstellar nebula. We propose that the nebula is ionized externally by the hot stars in the 30 Doradus star-forming region.
- ID:
- ivo://CDS.VizieR/J/A+A/588/A54
- Title:
- roAp star alpha Cir blue and red light curves
- Short Name:
- J/A+A/588/A54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on an analysis of high-precision, multi-colour photometric observations of the rapidly-oscillating Ap (roAp) star alpha Cir. These observations were obtained with the BRITE-Constellation, which is a coordinated mission of five nanosatellites that collects continuous millimagnitude-precision photometry of dozens of bright stars for up to 180-days at a time in two colours (~Johnson B and R). BRITE stands for BRight Target Explorer. The object Cir is the brightest roAp star and an ideal target for such investigations, facilitating the determination of oscillation frequencies with high resolution. This star is bright enough for complementary interferometry and time-resolved spectroscopy. Four BRITE satellites observed alpha Cir for 146d or 33 rotational cycles. Phasing the photometry according to the 4.4790d rotational period reveals qualitatively different light variations in the two photometric bands. The phased red-band photometry is in good agreement with previously-published WIRE data, showing a light curve symmetric about phase 0.5 with a strong contribution from the first harmonic. The phased blue-band data, in contrast, show an essentially sinusoidal variation. We model both light curves with Bayesian Photometric Imaging, which suggests the presence of two large-scale, photo- metrically bright (relative to the surrounding photosphere) spots. We also examine the high-frequency pulsation spectrum as encoded in the BRITE photometry. Our analysis establishes the stability of the main pulsation frequency over the last ~20-years, confirms the presence of frequency f_7_, which was not detected (or the mode not excited) prior to 2006, and excludes quadrupolar modes for the main pulsation frequency.
- ID:
- ivo://CDS.VizieR/J/other/IBVS/4433
- Title:
- Rosino-Guzzi variables in Sagitta
- Short Name:
- J/other/IBVS/443
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The list below gives accurate coordinates and IRAS identifications for all but one of the 123 red variable stars found by Rosino & Guzzi (1978A&AS...31..313R)) on a series of infrared plates.
- ID:
- ivo://CDS.VizieR/J/A+A/603/A106
- Title:
- Rotational periods in Cygnus OB2
- Short Name:
- J/A+A/603/A106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a near-infrared time-series photometry study in the field of Cygnus OB2 association (RA~20.55h, DE~41.2{deg}). Observations were carried out in the JHK bands at the WFCAM/UKIRT telescope over 112 observed nights. We investigated the occurrence of periodicity in the time-series and we found reliable periods for 894 candidate members.
- ID:
- ivo://CDS.VizieR/J/MNRAS/468/2745
- Title:
- Rotational properties of mCP stars
- Short Name:
- J/MNRAS/468/2745
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The magnetic chemically peculiar (mCP) stars of the upper main sequence exhibit strong, globally organized magnetic fields that are inclined to the rotational axis and facilitate the development of surface abundance inhomogeneities resulting in photometric and spectroscopic variability. Therefore, mCP stars are perfectly suited for a direct measurement of the rotational period without the need for any additional calibrations. We have investigated the rotational properties of mCP stars based on an unprecedentedly large sample consisting of more than 500 objects with known rotational periods. Using precise parallaxes from the Hipparcos and Gaia satellite missions, well-established photometric calibrations and state-of-the-art evolutionary models, we have determined the location of our sample stars in the Hertzsprung-Russell diagram and derived astrophysical parameters such as stellar masses, effective temperature, radii, inclinations and critical rotational velocities. We have confirmed the conservation of angular momentum during the main sequence evolution; no signs of additional magnetic braking were found. The inclination angles of the rotational axes are randomly distributed, although an apparent excess of fast rotators with comparable inclination angles has been observed. We have found a rotation rate of v/v_crit_>=0.5 for several stars, whose characteristics cannot be explained by current models. For the first time, we have derived the relationship between mass and rotation rate of mCP stars, and provide an analysis that links mass and rotation with magnetic field strength. Our sample is unique and offers crucial input for forthcoming evolutionary models that include the effects of magnetic fields for upper main sequence stars.
- ID:
- ivo://CDS.VizieR/J/A+A/566/A130
- Title:
- Rotation and variability of substellar objects
- Short Name:
- J/A+A/566/A130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Doppler Imaging produces 2D global maps of rotating objects using high-dispersion spectroscopy. When applied to brown dwarfs and extrasolar planets, this technique can constrain global atmospheric dynamics and/or magnetic effects on these objects in un- precedented detail. I present the first quantitative assessment of the prospects for Doppler Imaging of substellar objects with current facilities and with future giant ground-based telescopes. Observations will have the greatest sensitivity in K band, but the H and L bands will also be useful for these purposes. To assess the number and availability of targets, I also present a compilation of all measurements of photometric variability, rotation period (P), and projected rotational velocity (vsini) for brown dwarfs and exoplanets. Several bright objects are already accessible to Doppler Imaging with currently available instruments. With the development of giant ground-based telescopes, Doppler Imaging will become feasible for many dozens of brown dwarfs and for the few brightest directly imaged extrasolar planets (such as beta Pic b). The present set of measurements of P, vsini, and variability are incomplete for many objects, and the sample is strongly biased toward early-type objects (<L5). Thus, surveys to measure these quantities for later-type objects will be especially helpful in expanding the sample of candidates for global weather monitoring via Doppler Imaging.
