- ID:
- ivo://CDS.VizieR/J/ApJ/727/53
- Title:
- Red supergiant stars in the LMC. I.
- Short Name:
- J/ApJ/727/53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From previous samples of red supergiants (RSGs) by various groups, 191 objects are assembled to compose a large sample of RSG candidates in LMC. For 189 of them, the identity as an RSG is verified by their brightness and color indexes in several near- and mid-infrared bands related to the Two Micron All Sky Survey (2MASS) JHKs bands and the Spitzer/IRAC and Spitzer/MIPS bands. From the visual time-series photometric observations by the ASAS and MACHO projects which cover nearly 8-10 years, the period and amplitude of light variation are analyzed carefully using both the phase dispersion minimization and Period04 (Lenz, 2004CoAst.144...41L) methods.
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- ID:
- ivo://CDS.VizieR/J/A+A/616/A175
- Title:
- Red supergiant stars in the LMC. II.
- Short Name:
- J/A+A/616/A175
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The characteristics of infrared properties and mid-infrared (MIR) variability of red supergiant (RSG) stars in the Large Magellanic Cloud (LMC) are analyzed based on 12 bands of near-infrared (NIR) to MIR co-added data from 2MASS, Spitzer and WISE, and ~6.6 years of MIR time-series data collected by the ALLWISE and NEOWISE-R projects. 773 RSGs candidates are compiled from the literature and verified by using the color-magnitude diagram (CMD), spectral energy distribution (SED) and MIR variability. About 15% of valid targets in the IRAC1-IRAC2/IRAC2-IRAC3 diagram may show Polycyclic Aromatic Hydrocarbon (PAH) emission. We show that arbitrary dereddening Q parameters related to the IRAC4, S9W, WISE3, WISE4 and MIPS24 bands could be constructed based on a precise measurement of MIR interstellar extinction law. Several peculiar outliers in our sample are discussed, in which one outlier might be a RSG right before the explosion or an extreme asymptotic giant branch (AGB) star in the very late evolutionary stage based on the MIR spectrum and photometry. There are 744 identified RSGs in the final sample having both the WISE1- and WISE2-band time-series data. The results show that the MIR variability is increasing along with the increasing of brightness. There is a relatively tight correlation between the MIR variability, mass loss rate (MLR; in terms of K_S-WISE3 color) and the warm dust/continuum (in terms of WISE4 magnitude/flux), where the MIR variability is evident for the targets with K_S-WISE3>1.0mag and WISE4<6.5mag, while the rest of the targets show much smaller MIR variability. The MIR variability is also correlated with the MLR for which targets with larger variability also show larger MLR with an approximate upper limit of -6.1M_{sun}_/yr. The variability and luminosity may both be important for the MLR since the WISE4-band flux is increasing exponentially along with the degeneracy of luminosity and variability. The identified RSG sample has been compared with the theoretical evolutionary models and shown that the discrepancy between observation and evolutionary models can be mitigated by considering both variability and extinction.
- ID:
- ivo://CDS.VizieR/J/ApJ/754/35
- Title:
- Red supergiant stars in the SMC. II.
- Short Name:
- J/ApJ/754/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The characteristics of light variation of red supergiant (RSG) stars in the Small Magellanic Cloud (SMC) are analyzed based on the nearly 8-10 year data collected by the ASAS and MACHO projects. The 126 identified RSGs are classified into five categories accordingly: 20 with poor photometry, 55 with no reliable period, 6 with semi-regular variation, 15 with a long secondary period (LSP) and distinguishable short period, and 30 with only an LSP. For the semi-regular variables and the LSP variables with distinguishable short period, the K_S_-band period-luminosity (P-L) relation is analyzed and compared with that of the Galaxy, the Large Magellanic Cloud, and M33. It is found that the RSGs in these galaxies obey a similar P-L relation except for those in the Galaxy. In addition, the P-L relations in the infrared bands, namely, the 2MASS JHK_S_, Spitzer/IRAC, and Spitzer/MIPS 24 {mu}m bands, are derived with high reliability. The best P-L relation occurs in the Spitzer/IRAC [3.6] and [4.5] bands. Based on the comparison with the theoretical calculation of the P-L relation, the mode of pulsation of RSGs in the SMC is suggested to be the first-overtone radial mode.
- ID:
- ivo://CDS.VizieR/J/A+AS/93/311
- Title:
- Relative proper motions in NGC 362
- Short Name:
- J/A+AS/93/311
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Relative proper motions are determined for stars brighter than B~=17mag in a 1.5{deg}x1.5{deg} field centered on the globular cluster NGC 362. Proper motions and membership probabilities are tabulated for 488 stars within 10.2' of the cluster center. 14 astrographic plates with epoch differences up to 92 years were completely scanned, and each detectable object was stored. Proper motions were computed with an iterative central-overlap technique. A modal proper motion accuracy of 0.9 milliarcsec/year (mas/a) was achieved. NGC 362 appears projected onto the Small Magellanic Cloud (SMC), allowing to measure the proper motion of the cluster relative to extragalactic background stars. SMC stars were identified by position, proper motion and colour; the mean proper motion of these SMC candidates agrees well with the proper motions of SMC members known from the literature. The proper motion of NGC 362 relative to the SMC is +3.5+/-0.8mas/a in right ascension and -2.6+/-0.8mas/a in declination. For reasonable assumptions on the absolute proper motion of the SMC, the absolute proper motion and space motion of NGC 362 are computed. NGC 362 exhibits a highly eccentric orbit, typical for a member of the halo subgroup of the galactic globular cluster system. The perigalactic distance of NGC 362 is very small (<~1kpc), which raises the interesting question of how the cluster can survive the many passages near the galactic bulge over its lifetime.
- ID:
- ivo://CDS.VizieR/J/A+A/317/871
- Title:
- Revised spectral types of B-supergiants in the SMC
- Short Name:
- J/A+A/317/871
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The problem of the classification of metal poor stars, such as occur in the Small Magellanic Cloud (SMC), is discussed with reference to the applicability of the MK system in such an environment. An alternative method is presented here and applied to B-type supergiants in the SMC. A local reference system is first devised and then a transformation to MK spectral types is determined by comparing the trends of metal line strengths in these two systems. For the determination of the luminosity class, we emphasize the need to use the hydrogen Balmer line strengths independently of metal line-strength considerations. This method is used to determine new spectral types for 64 supergiants in the SMC, 75% of the sample requiring classifications different from previous findings. These new types result in much improved line strength - spectral type correlations for He, C, N, O, Mg and Si. Corresponding changes in the distribution of these stars in the Hertzsprung-Russell diagram of the SMC reveal more clearly than before the existence of a ridge which may be the SMC analogue of a similar feature found for the LMC by Fitzpatrick & Garmany (1990ApJ...363..119F). The group of very luminous supergiants lying above this ridge includes the LBV AV415 (R40), a property which this object has in common with LBVs in the Large Magellanic Cloud. Also, for the first time, clear examples of BN/BC supergiants are found in the SMC.
- ID:
- ivo://CDS.VizieR/J/AJ/139/878
- Title:
- RGB stars in 8 LMC clusters
- Short Name:
- J/AJ/139/878
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we discuss the properties of color-magnitude diagrams, age, metallicity, and radial velocities of eight massive Large Magellanic Cloud (LMC) clusters using data taken from the FORS2 multiobject spectrograph at the 8.2m Very Large Telescope/Unit Telescope 1. The strong near-infrared CaII triplet lines of red giant branch stars obtained from the high signal-to-noise ratio spectra are used to determine the metallicity and radial velocity of cluster members.
- ID:
- ivo://CDS.VizieR/J/AJ/142/61
- Title:
- RGB stars in LMC outer disk
- Short Name:
- J/AJ/142/61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The outer disk of the Large Magellanic Cloud (LMC) is studied in order to unveil clues about its formation and evolution. Complementing our previous studies in innermost fields (3kpc<~R<~7kpc), we obtained deep color-magnitude diagrams in six fields with galactocentric distances from 5.2kpc to 9.2kpc and different azimuths. The comparison with isochrones shows that while the oldest population is approximately coeval in all fields, the age of the youngest populations increases with increasing radius. This agrees with the results obtained in the innermost fields. Low-resolution spectroscopy in the infrared CaII triplet region has been obtained for about 150 stars near the tip of the red giant branch in the same fields. Radial velocities and stellar metallicities have been obtained from these spectra. The metallicity distribution of each field has been analyzed together with those previously studied.
- ID:
- ivo://CDS.VizieR/J/AJ/136/1703
- Title:
- Ridgelines of six intermediate-age SMC clusters
- Short Name:
- J/AJ/136/1703
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a photometric analysis of the star clusters Lindsay 1, Kron 3, NGC 339, NGC 416, Lindsay 38, and NGC 419 in the Small Magellanic Cloud (SMC), observed with the Hubble Space Telescope Advanced Camera for Surveys (ACS) in the F555W and F814W filters. Our color-magnitude diagrams (CMDs) extend ~3.5mag deeper than the main-sequence turnoff points, deeper than any previous data. Cluster ages were derived using three different isochrone models: Padova, Teramo, and Dartmouth, which are all available in the ACS photometric system. Fitting observed ridgelines for each cluster, we provide a homogeneous and unique set of low-metallicity, single-age fiducial isochrones.
- ID:
- ivo://CDS.VizieR/J/A+A/369/932
- Title:
- RI photometry of LMC carbon stars
- Short Name:
- J/A+A/369/932
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalogue of 7760 carbon stars in the Large Magellenic Cloud is presented. The stars were identified during a systematic survey of objective-prism plates taken with the UK 1.2m Schmidt Telescope. The catalogue is compared with other lists of carbon stars and the distribution of the carbon stars is discussed.
- ID:
- ivo://CDS.VizieR/J/A+AS/143/391
- Title:
- ROSAT HRI catalogue of LMC X-ray sources
- Short Name:
- J/A+AS/143/391
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ROSAT HRI LMC source catalogue is based on all 543 pointed observations of the ROSAT HRI between 1990 and 1998 with exposure times higher than 50 sec. The observations covered a 10 deg x 10 deg field including the LMC. The catalogue contains 397 X-ray sources. Sources showing flux variability in ROSAT HRI and PSPC are listed in Table 1. Table 2 contains HRI sources which were identified with known objects in other catalogues and literature. Table 3 is a list of new classifications. The whole source catalogue from HRI observations is given in Table 4.
