- ID:
- ivo://CDS.VizieR/J/PASP/120/1
- Title:
- HST WFPC2 star clusters in M31. II.
- Short Name:
- J/PASP/120/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper reports on a survey of star clusters in M31 based on archival images from the Hubble Space Telescope. Paper I reported results from images obtained with the Wide Field Planetary Camera 2 (WFPC2) and this paper reports results from the Advanced Camera for Surveys (ACS). The ACS survey has yielded a total of 339 star clusters, 52 of which mostly globular clusters were found to have been catalogued previously. As for the previous survey, the luminosity function of the clusters drops steeply for absolute magnitudes fainter than M_V_=-3; the implied cluster mass function has a turnover for masses less than a few hundred solar masses. The color-integrated magnitude diagram of clusters shows three significant features: (1) a group of very red, luminous objects: the globular clusters, (2) a wide range in color for the fainter clusters, representing a considerable range in age and reddening, and (3) a maximum density of clusters centered approximately at V=21, B-V=0.30, V-I=0.50, where there are intermediate-age, intermediate-mass clusters with ages close to 500 million years and masses of about 2000 solar masses. We give a brief qualitative interpretation of the distribution of clusters in the CMDs in terms of their formation and destruction rates.
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Search Results
- ID:
- ivo://CDS.VizieR/J/PASP/122/745
- Title:
- HST WFPC2 star clusters in M31. III.
- Short Name:
- J/PASP/122/745
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper describes the results of a Hubble Space Telescope (HST) WFPC2 search for star clusters in active star-formation regions of M31. Nine of the clusters were previously cataloged and 77 are new. Our 23 fields cover key areas of the galaxy's recent star-formation activity. We provide a catalog of positions and integrated magnitudes in four colors, taken with the 336W, 439W, 555W, and 814W filters of the HST.
- ID:
- ivo://CDS.VizieR/J/AJ/138/770
- Title:
- HST/WFPC survey of M31 bright young clusters
- Short Name:
- J/AJ/138/770
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the properties of 89 low-mass star clusters located in the vicinity of luminous young clusters ("blue globulars") in the disk of M31. Eighty-two of the clusters are newly detected. We have determined their integrated magnitudes and colors, based on a series of Hubble Space Telescope (HST)/Wide Field Planetary Camera 2 exposures in blue and red (HST filters F450W and F814W).
- ID:
- ivo://CDS.VizieR/J/MNRAS/431/1005
- Title:
- IC 2391 and Argus young stars
- Short Name:
- J/MNRAS/431/1005
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the possible connection between the open cluster IC 2391 and the unbound Argus association identified by the search for associations containing young stars survey. In addition to common kinematics and ages between these two systems, here we explore their chemical abundance patterns to confirm if the two substructures shared a common origin. We carry out a homogeneous high-resolution elemental abundance study of eight confirmed members of IC 2391 as well as six members of the Argus association using UVES spectra. We derive spectroscopic stellar parameters and abundances for Fe, Na, Mg, Al, Si, Ca, Ti, Cr, Ni and Ba. All stars in the open cluster and Argus association were found to share similar abundances with the scatter well within the uncertainties, where [Fe/H]=-0.04+/-0.03 for cluster stars and [Fe/H]=-0.06+/-0.05 for Argus stars. Effects of overionization/excitation were seen for stars cooler than roughly 5200K as previously noted in the literature. Also, enhanced Ba abundances of around 0.6dex were observed in both systems. The common ages, kinematics and chemical abundances strongly support the fact that the Argus association stars originated from the open cluster IC 2391. Simple modelling of this system finds this dissolution to be consistent with two-body interactions.
- ID:
- ivo://CDS.VizieR/J/AJ/135/823
- Title:
- ICMF of super star clusters
- Short Name:
- J/AJ/135/823
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The initial cluster mass function (ICMF) is a fundamental property of star formation in galaxies. To gauge its universality, we measure and compare the ICMFs in irregular and spiral galaxies. Our sample of irregular galaxies is based on 13 nearby galaxies selected from a volume-limited sample from the fifth data release of the Sloan Digital Sky Survey (SDSS), from which about 320 young (<=20Myr), massive (>~3x10^49M_{sun}_) clusters or associations were selected using an automated source extraction routine. The extinctions, ages, and masses were determined by comparing their u'g'i'z' magnitudes to those generated from starburst models.
- ID:
- ivo://CDS.VizieR/J/ApJ/425/122
- Title:
- IMF from UV stellar photometry
- Short Name:
- J/ApJ/425/122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UV stellar photometry is presented for 1563 stars within a 40' circular field in the LMC, excluding the 10'x10' field centered on R136 investigated earlier by Hill et al. (1993). Magnitudes are computed from images obtained by the Ultraviolet Imaging Telescope in bands centered at 1615A and 2558A. Stellar masses and extinctions are estimated for the stars in associations using the evolutionary models of Schaerer et al. (1993), assuming the age is 4Myr and that the local LMC extinction follows the Fitzpatrick (1985) 30 Dor extinction curve. The estimated slope of the initial mass function (IMF) for massive stars (>15M_{sun}_) within the Lucke and Hodge (LH) associations is {gamma}=-1.08+/-0.2. Initial masses and extinctions for stars not within LH associations are estimated assuming that the stellar age is either 4Myr or half the stellar lifetime, whichever is larger. The estimated slope of the IMF for massive stars not within LH associations is {gamma}=-1.74+/-0.3 (assuming continuous star formation), compared with {gamma}=-1.35, and {gamma}=-1.7+/-0.5, obtained for the Galaxy by Salpeter (1955) and Scalo (1986), respectively, and {gamma}=-1.6 obtained for massive stars in the Galaxy by Garmany, Conti, & Chiosi (1982). The shallower slope of the association IMF suggests that not only is the star formation rate higher in associations, but that the local conditions favor the formation of higher mass stars there. We make no corrections for binaries or incompleteness.
- ID:
- ivo://CDS.VizieR/J/ApJ/746/154
- Title:
- Improved kinematic parallaxes for Sco-Cen members
- Short Name:
- J/ApJ/746/154
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the ages and star formation history of the F-type stars in the Upper Scorpius (US), Upper Centaurus-Lupus (UCL), and Lower Centaurus-Crux (LCC) subgroups of Scorpius-Centaurus (Sco-Cen), the nearest OB association. Our parent sample is the kinematically selected Hipparcos sample of de Zeeuw et al. (1999, Cat. J/AJ/117/354), restricted to the 138 F-type members. We have obtained classification-resolution optical spectra and have also determined the spectroscopic accretion disk fraction. With Hipparcos and 2MASS photometry, we estimate the reddening and extinction for each star and place the candidate members on a theoretical H-R diagram. For each subgroup we construct empirical isochrones and compare to published evolutionary tracks.
- ID:
- ivo://CDS.VizieR/J/ApJS/172/663
- Title:
- Infrared observations of the Pleiades
- Short Name:
- J/ApJS/172/663
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We make use of new near- and mid-IR photometry of the Pleiades cluster in order to help identify proposed cluster members. We also use the new photometry with previously published photometry to define the single-star main-sequence locus at the age of the Pleiades in a variety of color-magnitude planes. The new near- and mid-IR photometry extend effectively 2 mag deeper than the 2MASS All-Sky Point Source catalog, and hence allow us to select a new set of candidate very low-mass and substellar mass members of the Pleiades in the central square degree of the cluster. We identify 42 new candidate members fainter than K_s_=14 (corresponding to 0.1M_{sun}_). These candidate members should eventually allow a better estimate of the cluster mass function to be made down to of order 0.04M_{sun}_. We also use new IRAC data, in particular the images obtained at 8um, in order to comment briefly on interstellar dust in and near the Pleiades.
- ID:
- ivo://CDS.VizieR/J/ApJ/784/126
- Title:
- Infrared photometry of all known members in Taurus
- Short Name:
- J/ApJ/784/126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have compiled photometry at 3.4, 4.6, 12, and 22{mu}m from the all-sky survey performed by the Wide-field Infrared Survey Explorer (WISE) for all known members of the Taurus complex of dark clouds. Using these data and photometry from the Spitzer Space Telescope, we have identified members with infrared excess emission from circumstellar disks and have estimated the evolutionary stages of the detected disks, which include 31 new full disks and 16 new candidate transitional, evolved, evolved transitional, and debris disks. We have also used the WISE All-Sky Source Catalog to search for new disk-bearing members of Taurus based on their red infrared colors. Through optical and near-infrared spectroscopy, we have confirmed 26 new members with spectral types of M1-M7. The census of disk-bearing stars in Taurus should now be largely complete for spectral types earlier than ~M8(M{>~}0.03M_{sun}_).
- ID:
- ivo://CDS.VizieR/J/ApJ/647/1180
- Title:
- Infrared photometry of Taurus SFR
- Short Name:
- J/ApJ/647/1180
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for new members of the Taurus star-forming region using the Infrared Array Camera (IRAC) aboard the Spitzer Space Telescope. With IRAC images of 29.7deg^2^ of Taurus at 3.6, 4.5, 5.8, and 8.0um, we have identified sources with red mid-infrared colors indicative of disk-bearing objects and have obtained optical and infrared spectra of 23 of these candidate members. Through this work, we have discovered 13 new members of Taurus, two of which have spectral types later than M6 and thus are likely to be brown dwarfs, according to the theoretical evolutionary models of Chabrier & Baraffe (2000ApJ...542..464C). This survey indicates that the previous census of Taurus has a completeness of 80% for members with disks. The new members that we have found do not significantly modify the previously measured distributions of Taurus members as a function of position, mass, and extinction. For instance, we find no evidence for a population of highly reddened brown dwarfs ({LAMBDA}_K_~2) that has been missed by previous optical and near-infrared surveys, which suggests that brown dwarf disks are not significantly more flared than disks around stars. In addition to the new members, we also present IRAC photometry for the 149 previously known members that appear within this survey, which includes 27 objects later than M6.
