- ID:
- ivo://CDS.VizieR/J/AJ/99/784
- Title:
- IR photometry of LMC long-period variables
- Short Name:
- J/AJ/99/784
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Infrared JHK photometry and visual spectra have been obtained for a large sample of long-period variables (LPVs) in the Large Magellanic Cloud (LMC). Various aspects of the asymptotic giant branch (AGB) evolution of LPVs are discussed using these data. The birth/death rate of LPVs of different ages in the LMC is compared with the birth rates of appropriate samples of planetary nebulae clump stars, Cepheids, and OH/IR stars. It appears that there are much fewer large-amplitude LPVs per unit galactic stellar mass in the LMC than in the Galaxy. We suggest that this may be due to the fact that the evolved intermediate-age AGB stars in the LMC often turn into carbon stars, which tend to have smaller pulsation amplitudes than M stars. There is also a major discrepancy between the number of LPVs in the LMC (and in the Galaxy) and the number predicted by the theories of AGB evolution, pulsation, and mass loss. A distance modulus to the LMC of 18.66+0.05 is derived by comparing the LMC LPVs with P~200days with the 47 Tucanae Mira variables in the (K, logP) plane. The (K, logP) relation is also used to examine the tilt of the LMC populations of old and intermediate-age stars.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/442/273
- Title:
- IR photometry of NGC 1893 variables
- Short Name:
- J/MNRAS/442/273
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present time series photometry of 104 variable stars in the cluster region NGC 1893. The association of the present variable candidates to the cluster NGC 1893 has been determined by using (U-B)/(B-V) and (J-H)/(H-K) two colour diagrams, and V/(V-I) colour-magnitude diagram. 45 stars are found to be main-sequence variables and these could be B-type variable stars associated with the cluster. We classified these objects as {beta} Cep, slowly pulsating B stars and new class variables as discussed by Mowlavi et al. (2013, Cat. J/A+A/554/A108). These variable candidates show ~0.005 to ~0.02mag brightness variations with periods of <1.0d. 17 new class variables are located in the H-R diagram between the slowly pulsating B stars and {delta} Scuti variables. Pulsation could be one of the causes for periodic brightness variations in these stars. The X-ray emission of present main-sequence variables associated with the cluster lies in the saturated region of X-ray luminosity versus period diagram and follows the general trend by Pizzolato et al. (2003, Cat. J/A+A/397/147).
- ID:
- ivo://CDS.VizieR/J/MNRAS/481/4206
- Title:
- IRSF survey of variable stars in the SMC
- Short Name:
- J/MNRAS/481/4206
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A very long-term near-infrared variable star survey towards the Large and Small Magellanic Clouds (LMC and SMC) was carried out using the 1.4m InfraRed Survey Facility at the South African Astronomical Observatory. This project was initiated in 2000 December in the LMC, and in 2001 July in the SMC. Since then an area of 3deg^2^ along the bar in the LMC and an area of 1deg^2^ in the central part of the SMC have been repeatedly observed. This survey is ongoing, but results obtained with data taken until 2017 December are reported in this paper. Over more than 15yr we have observed the two survey areas more than one hundred times. This is the first survey that provides near-infrared time-series data with such a long time baseline and on such a large scale. This paper describes the observations in the SMC and publishes a point source photometric catalogue, a variable source catalogue, and time-series data.
- ID:
- ivo://CDS.VizieR/J/AJ/151/146
- Title:
- IRS spectra with features of crystalline silicates
- Short Name:
- J/AJ/151/146
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The crystalline silicate features are mainly reflected in infrared bands. The Spitzer Infrared Spectrograph (IRS) collected numerous spectra of various objects and provided a big database to investigate crystalline silicates in a wide range of astronomical environments. We apply the manifold ranking algorithm to perform a systematic search for the spectra with crystalline silicate features in the Spitzer IRS Enhanced Products available. In total, 868 spectra of 790 sources are found to show the features of crystalline silicates. These objects are cross-matched with the SIMBAD database as well as with the Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST)/DR2 (Luo et al. 2016, Cat. V/149). The average spectrum of young stellar objects shows a variety of features dominated either by forsterite or enstatite or neither, while the average spectrum of evolved objects consistently present dominant features of forsterite in AGB, OH/IR, post-AGB, and planetary nebulae. They are identified optically as early-type stars, evolved stars, galaxies and so on. In addition, the strength of spectral features in typical silicate complexes is calculated. The results are available through CDS for the astronomical community to further study crystalline silicates.
- ID:
- ivo://CDS.VizieR/J/AJ/155/99
- Title:
- IR variability among YSOs in the Serpens South cluster
- Short Name:
- J/AJ/155/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a time-variability study of young stellar objects (YSOs) in the Serpens South cluster performed at 3.6 and 4.5 {mu}m with the Spitzer Space Telescope; this study is part of the Young Stellar Object VARiability project. We have collected light curves for more than 1500 sources, including 85 cluster members, over 38 days. This includes 44 class I sources, 19 sources with flat spectral energy distributions (SEDs), 17 class II sources, and five diskless YSO candidates. We find a high variability fraction among embedded cluster members of ~70%, whereas young stars without a detectable disk display no variability. We detect periodic variability for 32 sources with periods primarily in the range of 0.2-14 days and a subset of fast rotators thought to be field binaries. The timescale for brightness changes are shortest for stars with the most photospheric SEDs and longest for those with flat or rising SEDs. While most variable YSOs become redder when fainter, as would be expected from variable extinction, about 10% get bluer as they get fainter. One source, SSTYSV J183006.13-020108.0, exhibits "cyclical" color changes.
- ID:
- ivo://CDS.VizieR/J/ApJ/850/137
- Title:
- ISLAndS project. III. Variable stars
- Short Name:
- J/ApJ/850/137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a census of variable stars in six M31 dwarf spheroidal satellites observed with the Hubble Space Telescope. We detect 870 RR Lyrae (RRL) stars in the fields of And I (296), II (251), III (111), XV (117), XVI (8), and XXVIII (87). We also detect a total of 15 Anomalous Cepheids, three eclipsing binaries, and seven field RRL stars compatible with being members of the M31 halo or the Giant Stellar Stream. We derive robust and homogeneous distances to the six galaxies using different methods based on the properties of the RRL stars. Working with the up-to-date set of Period-Wesenheit (I, B-I) relations published by Marconi et al., we obtain distance moduli of {mu}0=[24.49, 24.16, 24.36, 24.42, 23.70, 24.43]mag (respectively), with systematic uncertainties of 0.08mag and statistical uncertainties <0.11mag. We have considered an enlarged sample of 16 M31 satellites with published variability studies, and compared their pulsational observables (e.g., periods and amplitudes) with those of 15 Milky Way satellites for which similar data are available. The properties of the (strictly old) RRL in both satellite systems do not show any significant difference. In particular, we found a strikingly similar correlation between the mean period distribution of the fundamental RRL pulsators (RRab) and the mean metallicities of the galaxies. This indicates that the old RRL progenitors were similar at the early stage in the two environments, suggesting very similar characteristics for the earliest stages of evolution of both satellite systems.
- ID:
- ivo://CDS.VizieR/J/A+A/406/51
- Title:
- ISO long period variables in SMC
- Short Name:
- J/A+A/406/51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This article presents the study of the light curves extracted from the MACHO database of a sample of stars observed by the Infrared Space Observatory in the Small Magellanic Cloud. These stars belong to the ISO Mini-Survey catalogue of the Magellanic Clouds (ISO MCMS, Loup et al., in preparation). Most of them are in the asymptotic giant branch (AGB) and supergiant phases. The dominant period and amplitude of pulsation have been derived and the stars have been classified as Mira or Semi Regular pulsators.
- ID:
- ivo://CDS.VizieR/J/AcA/54/347
- Title:
- IVB mag of LMC ellipsoidal variables
- Short Name:
- J/AcA/54/347
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used the OGLE-II and OGLE-III photometry of red giants in the Large Magellanic Cloud to select and study objects revealing ellipsoidal variability. We detected 1546 candidates for long period ellipsoidal variables and 121 eclipsing binary systems with clear ellipsoidal modulation.
- ID:
- ivo://CDS.VizieR/J/MNRAS/384/1583
- Title:
- JHK light curves of RR Lyr
- Short Name:
- J/MNRAS/384/1583
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present infrared JHK time series photometry of the variable star RR Lyr, that allows us to construct the first complete and accurate infrared light curves for this star. The derived mean magnitudes are <J>=6.74+/-0.02, <H>=6.60+/-0.03 and <K>=6.50+/-0.02. The <K> magnitude is used to estimate the reddening, the mass, the mean luminosity and the temperature of this variable star. The use of these RR Lyr data provides a more accurate absolute calibration of the P-L_K_-[Fe/H] relation, and a distance modulus (m-M)0=18.48+/-0.11 to the globular cluster Reticulum in the Large Magellanic Cloud.
- ID:
- ivo://CDS.VizieR/J/PAZh/37/34
- Title:
- JHKLM light curves of WR 140
- Short Name:
- J/PAZh/37/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of our infrared observations of WR 140 (=V1687 Cyg) in 2001-2010.
