- ID:
- ivo://CDS.VizieR/J/A+A/482/585
- Title:
- JHK photometry of stars in Sh 2-212
- Short Name:
- J/A+A/482/585
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CO millimetre observations of this region obtained at the IRAM 30-m telescope to investigate the distribution of associated molecular material. We also use deep JHK observations obtained at the CFHT to study the stellar content of the region, and radio observations obtained at the VLA to look for the presence of an ultra-compact (UC) HII region and for maser emission.
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- ID:
- ivo://CDS.VizieR/J/AJ/107/2120
- Title:
- JHK photometry of the OMC2 region
- Short Name:
- J/AJ/107/2120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an unbiased survey at 1.25-2.2um of a 0.025sq.deg. region surrounding the core of Orion Molecular Cloud 2 (OMC-2). Analysis of the source counts and colors indicates that the majority of the sources brighter than K=+13 are not field stars. They must be members of a young association or associations within the survey area. The K band luminosity function (corrected for field star contamination using model calculations) exhibits a drop in counts at magnitudes fainter than K=+13 (~0.15L_{sun}_). This is most easily explained by assuming that the association(s) are young. The lowest mass stars simply have not yet reached the main sequence. The distribution of colors across the region shows moderate correlation with molecular gas, but both reddened and unreddened stars are present along most lines of sight. Considerable reflection nebulosity is present in the region of the core cluster of OMC2 itself. Of particular interest are the thin streamers emanating from the star J9, which may be the remnant of a bipolar nebula produced by the star in the recent past.
- ID:
- ivo://CDS.VizieR/J/AJ/150/132
- Title:
- JHK photometry of 1203 variables in ONC
- Short Name:
- J/AJ/150/132
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using UKIRT on Mauna Kea, we have carried out a new near-infrared J, H, K monitoring survey of almost a square degree of the star-forming Orion Nebula Cluster with observations on 120 nights over three observing seasons, spanning a total of 894 days. We monitored ~15000 stars down to J~20 using the WFCAM instrument, and have extracted 1203 significantly variable stars from our data. By studying variability in young stellar objects (YSOs) in the H-K, K color-magnitude diagram, we are able to distinguish between physical mechanisms of variability. Many variables show color behavior indicating either dust-extinction or disk/accretion activity, but we find that when monitored for longer periods of time, a number of stars shift between these two variability mechanisms. Further, we show that the intrinsic timescale of disk/accretion variability in young stars is longer than that of dust-extinction variability. We confirm that variability amplitude is statistically correlated with evolutionary class in all bands and colors. Our investigations of these 1203 variables have revealed 73 periodic AA Tau type variables, many large-amplitude and long-period (P>15 days) YSOs, including three stars showing widely spaced periodic brightening events consistent with circumbinary disk activity, and four new eclipsing binaries. These phenomena and others indicate the activity of long-term disk/accretion variability processes taking place in young stars. We have made the light curves and associated data for these 1203 variables available online.
- ID:
- ivo://CDS.VizieR/J/A+A/365/110
- Title:
- JHK photometry of Vega-type and PMS stars
- Short Name:
- J/A+A/365/110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- File table1.dat contains near-infrared JHK magnitudes of a sample of 18 Vega-like and post-T Tauri stars observed by the EXPORT collaboration. File table2.dat contains near-infrared JHK magnitudes of a sample of 4 pre-main sequence stars observed by EXPORT. The data were taken during four observing runs in the period May 1998 to January 1999.
- ID:
- ivo://CDS.VizieR/J/MNRAS/353/1025
- Title:
- JHK photometry of 4 W51 star clusters
- Short Name:
- J/MNRAS/353/1025
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present sub-arcsecond (0.35-0.9"), near-infrared J-, H- and K-band photometric observations of six fields along the W51 giant molecular cloud (W51 GMC). Our observations reveal four new, embedded clusters and provide a new high-resolution (0.35") view of the W51 IRS2 (G49.5-0.4) region. The cluster associated with G48.9-0.3 is found to be a double cluster enclosed in a nest of near-infrared nebulosity. We construct stellar surface density maps for four major clusters in the W51 GMC. These unveil the underlying hierarchical structure.
- ID:
- ivo://CDS.VizieR/J/AJ/126/1916
- Title:
- JHK photometry of young clusters near the Sun
- Short Name:
- J/AJ/126/1916
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of near-infrared surveys of young (<~a few 10^6^yr) stellar groups and clusters within 1kpc from the Sun, based on an extensive search of the literature from the past ten years. We find 143 surveys from 69 published articles, covering 73 different regions. The number distribution of stars in a region has a median of 28 and a mean of 100. About 80% of the stars are in clusters with at least 100 members. By a rough classification of the groups and clusters based on the number of their associated stars, we show that most of the stars form in large clusters. The spatial distribution of catalogued regions in the Galactic plane shows a relative lack of observed stellar groups and clusters in the range 270{deg}<l<60{deg} of Galactic longitude, reflecting our location between the Local and Sagittarius arms. This compilation is intended as a useful resource for future studies of nearby young regions of multiple star formation.
- ID:
- ivo://CDS.VizieR/J/A+A/472/835
- Title:
- JHKs and GLIMPSE photometry of RCW 120
- Short Name:
- J/A+A/472/835
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To investigate the process of star formation triggered by the expansion of an HII region, we present a multi-wavelength analysis of the Galactic HII region RCW 120 and its surroundings. The collect and collapse model predicts that the layer of gas and dust accumulated between the ionization and shock fronts during the expansion of the HII region collapses and forms dense fragments, giving rise to potential sites of massive-star formation. The aim of our study is to look for such massive fragments and massive young stars on the borders of RCW 120. We mapped the RCW 120 region in the cold dust continuum emission at 1.2 mm to search for these fragments. We supplemented this study with the available near- (2MASS) and mid-IR (GLIMPSE) data to locate the IR sources observed towards this region and to analyse their properties. We then compared the observational results with the predictions of Hosokawa & Inutsuka's model (2005ApJ...623..917H; 2006ApJ...646..240H).
- ID:
- ivo://CDS.VizieR/J/A+A/496/177
- Title:
- JHKs and GLIMPSE photometry of RCW 120
- Short Name:
- J/A+A/496/177
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This study deals with the star formation triggered by HII regions. We wish to take advantage of the very simple morphology of RCW 120 - a perfect bubble - to understand the mechanisms triggering star formation around an HII region and to establish what kind of stars are formed there. We present 870um observations of RCW 120, obtained with the APEX-LABOCA camera. These show the distribution of cold dust, and thus of neutral material. We use Spitzer-MIPS observations at 24um and 70um to detect the young stellar objects present in this region and to estimate their evolutionary stages.
- ID:
- ivo://CDS.VizieR/J/MNRAS/380/1497
- Title:
- JHKs & GLIMPSE photometry towards G305.2+0.2
- Short Name:
- J/MNRAS/380/1497
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep, wide field J, H and Ks images taken with Infrared Imager and Spectrometer 2 (IRIS2) on the Anglo-Australian Telescope, towards the massive star formation region G305.2+0.2. Combined with 3.6, 4.5, 5.8 and 8.0um data from the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) survey on the Spitzer Space Telescope, we investigate the properties of the embedded stellar populations. After removing contamination from foreground stars, we separate the sources based on their infrared (IR) colour. Strong extended emission in the GLIMPSE images hampers investigation of the most embedded sources towards the known sites of massive star formation. However, we find a sizeable population of IR excess sources in the surrounding region free from these completeness effects. Investigation reveals the recent star formation activity in the region is more widespread than previously known.
- ID:
- ivo://CDS.VizieR/J/MNRAS/385/1045
- Title:
- JHKsIc photometry of AGB in Phoenix dwarf gal.
- Short Name:
- J/MNRAS/385/1045
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- JHKs near-infrared photometry of stars in the Phoenix dwarf galaxy is presented and discussed. Combining these data with the optical photometry of Massey et al. (2007, Cat. <J/AJ/133/2393>) allows a rather clean separation of field stars from Phoenix members. The discovery of a Mira variable (P=425d), which is almost certainly a carbon star, leads to an estimate of the distance modulus of 23.10+/-0.18 that is consistent with other estimates and indicates the existence of a significant population of age ~2Gyr. The two carbon stars of Da Costa have Mbol=-3.8 and are consistent with belonging to a population of similar age; some other possible members of such a population are identified. A Da Costa non-carbon star is {Delta}Ks~0.3mag brighter than these two carbon stars. It may be an asymptotic giant branch star of the dominant old population. The nature of other stars lying close to it in the Ks, (J-Ks) diagram needs studying.
