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- ID:
- ivo://CDS.VizieR/J/ApJ/674/336
- Title:
- Spitzer observations of NGC 1333
- Short Name:
- J/ApJ/674/336
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comprehensive analysis of structure in the young, embedded cluster, NGC 1333 using members identified with Spitzer and 2MASS photometry based on their IR-excess emission. A total of 137 members are identified in this way, composed of 39 protostars and 98 more evolved pre-main-sequence stars with disks. Of the latter class, four are transition/debris disk candidates.
- ID:
- ivo://CDS.VizieR/J/A+A/272/235
- Title:
- Stars in the dark cloud L1251
- Short Name:
- J/A+A/272/235
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The distance of the dark cloud L1251 was estimated from observations made at the Konkoly Observatory between 1985 and 1991. The spectral classification and the H{alpha} emission features were measured on objective-prism plates taken with the 60/80/180 Schmidt telescope; the photometry was derived from observations made on photographic plates with emulsion-filter combinations giving magnitudes in the Johnson photometric system. The distance of the cloud was found to be 300+/-50pc.
- ID:
- ivo://CDS.VizieR/J/ApJS/251/29
- Title:
- Stellar bow shock nebulae spectroscopic obs.
- Short Name:
- J/ApJS/251/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Arcuate mid-infrared nebulae known as stellar bow shock nebulae (SBNe) have been previously hypothesized to be supported by the strong stellar winds and/or luminosity of massive early-type stars. We present an optical spectroscopic survey of 84 stars identified from mid-infrared images as candidate SBN-supporting stars. Eighty-one of 84 sources, 96%, are O or early-B spectral types. K-band luminosities for a larger sample of 289 stars at the centers of bow shock nebulae are overwhelmingly consistent with OB stars. This affirms both that SBNe are supported by massive stars and that arcuate mid-infrared nebulae are reliable indicators of the presence of a massive star. The radial velocity dispersions of these systems and detections of double-lined systems indicate that at least 27 of the 74 systems with multiple observations (>36%) are candidate multiple-star systems. This rate is consistent with observed multiplicity rates of field OB stars detected with similar radial velocity surveys and lower than, but not inconsistent with, the multiplicity rates of OB stars in clusters and associations.
- ID:
- ivo://CDS.VizieR/J/AJ/98/1305
- Title:
- Stellar content of NGC 346
- Short Name:
- J/AJ/98/1305
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using CCD UBV photometry and spectroscopy, we have investigated the stellar content of NGC 346, the brightest H II region in the SMC. Spectra of 42 stars confirm that 33 are of O type, of which 11 are of type O6.5 or earlier; this is as many early-type O stars as is known in the rest of the SMC. From the spectroscopy and photometry we are able to construct an H-R diagram which is essentially complete down to ~10M_{sun}_. We find an initial mass-function slope {GAMMA}=-1.9, similar to that found for massive stars near the Sun and in the LMC: the presence of six stars in the mass range 40-85M_{sun}_ suggests that the upper-mass limit of the IMF is also not appreciably lower in the SMC than it is in the Galaxy. Our photometry has identified five probable red supergiants of which one was previously known. These stars, plus two B supergiants, are evolved stars of considerably lower mass (15M_{sun}_) than many of the unevolved cluster members. Most of these lower-mass, evolved stars form a spatially distinct subgroup; we believe that NGC 346 thus provides an example of sequential star formation in the SMC. We also have identified a background field population of 5M_{sun}_ stars. We find that the ionizing flux from the hot stars is consistent with the previously known Half nebular luminosity. Finally, we discuss the enigmatic W-R binary HD 5980, which our point-spread-function fitting has identified as a close visual double.
- ID:
- ivo://CDS.VizieR/J/AZh/87/853
- Title:
- Stellar groups of Orion's Sword region
- Short Name:
- J/AZh/87/853
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The region of Orion's Sword with coordinates RA=83.79{deg}, DE=-5.20{deg} and a size of 1.0{deg}x2.5{deg} is analyzed. We compiled a master catalog of stars observed in the optical, containing positions, proper motions, and UBV photometry for 1634 stars. Using the nearest-neighbor-distance technique, we subdivided the region into stellar groups with different numbers of members. The positions of five groups coincide with known clusters, and two groups coincide with aggregates of stars with H{alpha} emission. We have identified groups with low membership that are moving away from the system. We also considered the kinematic structure of the groups using the AD-diagram method we developed earlier. Most of the stellar clusters and groups display similar kinematics, with the exception of the group OMC-2, which is moving toward its own apex. We also confirmed the existence of the kinematic star group 189 discovered earlier; its position is close to the cluster NGC 1977, and it is probably a component of its corona.
- ID:
- ivo://CDS.VizieR/J/ApJS/193/25
- Title:
- The NAN complex. II. MIPS observations
- Short Name:
- J/ApJS/193/25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observations of ~7deg^2^ of the North American and Pelican Nebulae region at 24, 70, and 160um with the Spitzer Space Telescope Multiband I] ing Photometer for Spitzer (MIPS). We incorporate the MIPS observations with earlier Spitzer Infrared Array Camera (IRAC) observations, as well as archival near-infrared (IR) and optical data. We use the MIPS data to identify 1286 young stellar object (YSO) candidates. IRAC data alone can identify 806 more YSO candidates, for a total of 2076 YSO candidates. Prior to the Spitzer observations, there were only ~200 YSOs known in this region. Three subregions within the complex are highlighted as clusters: the Gulf of Mexico, the Pelican, and the Pelican's Hat. The Gulf of Mexico cluster is subject to the highest extinction (A_V_ at least ~30) and has the widest range of infrared colors of the three clusters, including the largest excesses and by far the most point-source detections at 70um. Just 3% of the cluster members were previously identified; we have redefined this cluster as about 10-100 times larger (in projected area) than was previously realized.
- ID:
- ivo://CDS.VizieR/J/ApJ/697/787
- Title:
- The NAN complex. I. IRAC observations
- Short Name:
- J/ApJ/697/787
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a 9deg^2^ map of the North American and Pelican Nebulae regions obtained in all four Infrared Array Camera (IRAC) channels with the Spitzer Space Telescope. The resulting photometry is merged with that at JHKs from Two Micron All Sky Survey and a more spatially limited BVI survey from previous ground-based work. We use a mixture of color-color diagrams to select a minimally contaminated set of more than 1600 objects that we claim are young stellar objects (YSOs) associated with the star-forming region. Because our selection technique uses infrared excess as a requirement, our sample is strongly biased against inclusion of Class III YSOs. The distribution of IRAC spectral slopes for our YSOs indicates that most of these objects are Class II, with a peak toward steeper spectral slopes but a substantial contribution from a tail of Flat spectrum and Class I type objects. By studying the small fraction of the sample that is optically visible, we infer a typical age of a few Myr for the low-mass population. The young stars are clustered, with about a third of them located in eight clusters that are located within or near the LDN 935 dark cloud. Half of the YSOs are located in regions with surface densities higher than 1000YSOs/deg^2^. The Class I objects are more clustered than the Class II stars.
- ID:
- ivo://CDS.VizieR/J/PAZh/27/841
- Title:
- UBV and line identification of V1853 Cyg
- Short Name:
- J/PAZh/27/841
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photoelectric and spectroscopic observations of the protoplanetary object V1853 Cyg, a B supergiant with an IR excess, are given. The observations were carried out with a UBV photometer attached to the 60-cm Zeiss telescope at the Crimean Station of the Stenberg Astronomical Institute.
- ID:
- ivo://CDS.VizieR/J/ApJS/104/71
- Title:
- UBV photometry of OB associations in LMC superbubbles
- Short Name:
- J/ApJS/104/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This work presents UBV photometry of the stellar populations associated with seven superbubble nebulae and five classical H II regions in the Large Magellanic Cloud. Although the nebular morphology of the superbubbles appears to be substantially evolved compared to the classical nebulae, the color-magnitude diagrams do not reveal any noticeable correlation between the resident stellar population and nebular morphology. The photometry presented here will be used in a forthcoming paper to examine further the stellar content and dynamics of these superbubbles.
