- ID:
- ivo://CDS.VizieR/J/ApJ/833/193
- Title:
- MYStIX candidate protostars
- Short Name:
- J/ApJ/833/193
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Massive Young Star-Forming Complex in Infrared and X-ray (MYStIX) project provides a new census on stellar members of massive star-forming regions within 4kpc. Here the MYStIX Infrared Excess catalog and Chandra-based X-ray photometric catalogs are mined to obtain high-quality samples of Class I protostars using criteria designed to reduce extragalactic and Galactic field star contamination. A total of 1109 MYStIX Candidate Protostars (MCPs) are found in 14 star-forming regions. Most are selected from protoplanetary disk infrared excess emission, but 20% are found from their ultrahard X-ray spectra from heavily absorbed magnetospheric flare emission. Two-thirds of the MCP sample is newly reported here. The resulting samples are strongly spatially associated with molecular cores and filaments on Herschel far-infrared maps. This spatial agreement and other evidence indicate that the MCP sample has high reliability with relatively few "false positives" from contaminating populations. But the limited sensitivity and sparse overlap among the infrared and X-ray subsamples indicate that the sample is very incomplete with many "false negatives." Maps, tables, and source descriptions are provided to guide further study of star formation in these regions. In particular, the nature of ultrahard X-ray protostellar candidates without known infrared counterparts needs to be elucidated.
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Search Results
- ID:
- ivo://CDS.VizieR/J/PASJ/64/96
- Title:
- Near-infrared survey of bright rimmed clouds
- Short Name:
- J/PASJ/64/96
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We conducted wide-field near-infrared imaging observations of 32 bright rimmed clouds (BRCs). Given a detection limit of 17.7mag at the K-band, we identified 2099 objects as young stellar object (YSO) candidates that displayed near-infrared excesses. Their masses, estimated from luminosities, range from 0.006M_{sun}_ to 2.7M_{sun}_. The candidates are not uniformly distributed. For 21 BRCs, more than half of the associated YSO candidates are located inside the cloud. We found clear evidence of triggered star formation. The number of YSO candidates is not correlated with the core mass of the molecular clouds. Instead, the YSO number increases with increasing UV photon flux from the exciting star illuminating the cloud surface. UV radiation activates star formation in the BRCs.
- ID:
- ivo://CDS.VizieR/J/A+A/553/A48
- Title:
- Near-infrared variability in RCW 38
- Short Name:
- J/A+A/553/A48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We want to study the content of young stellar objects in the RCW 38 cluster by means of multi-epoch variability studies. We performed a three-month near-infrared (NIR) monitoring campaign of the young cluster RCW 38 using the 80cm IRIS telescope near Cerro Armazones, Chile. Variability data with a median sampling of 1 day was gathered for 1026 sources, while a total of 3433 sources in JHK could be studied in the co-added, deep images with a completeness limit of K<15mag.
- ID:
- ivo://CDS.VizieR/J/A+A/481/123
- Title:
- Near-IR IFU spectroscopy of HH99B
- Short Name:
- J/A+A/481/123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim at characterising the morphology and the physical parameters governing the shock physics of the Herbig-Haro object HH99B. We obtained SINFONI-SPIFFI IFU spectroscopy (R~2000-4000) between 1.10 and 2.45{mu}m detecting more than 170 emission lines, that, to a large extent, have never observed before in a Herbig-Haro object. Most of them come from ro-vibrational transitions of molecular hydrogen (v_up_<=7, E_up_~<38000K) and [FeII] (E_up_~<30000K). In addition, we observed several hydrogen and helium recombination lines, along with fine-structure lines of ionic species. All the brightest lines appear resolved in velocity. Intensity ratios of ionic lines were compared with predictions of NLTE models to derive bi-dimensional maps of extinction and electron density, along with estimates of temperature, fractional ionisation, and atomic hydrogen post-shock density. The H2 line intensities were interpreted in the framework of Boltzmann diagrams, from which we have derived extinction and temperature maps of the molecular gas. From the intensity maps of bright lines (i.e. H2 2.122{mu}m and [FeII]1.644{mu}m), the kinematical properties of the shock(s) at work in the region were delineated. Finally, from selected [FeII] lines, constraints on the spontaneous emission coefficients of the 1.257, 1.321, and 1.644{mu}m lines are provided.
- ID:
- ivo://CDS.VizieR/J/ApJ/693/430
- Title:
- Near-IR photometry of Sh2-157 and Sh2-152
- Short Name:
- J/ApJ/693/430
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Near-infrared JHK' and H_2_{nu}=1-0S(1) imaging observations of the star-forming regions Sh2-157 and Sh2-152 are presented. The data reveal a cluster of young stars associated with H_2_ line emission in each region. Additionally, many IR point sources are found in the dense core of each molecular cloud. Most of these sources exhibit infrared color excesses typical of T Tauri stars, Herbig Ae/Be stars, and protostars. Several display the characteristics of massive stars. We calculate histograms of the K'-magnitude and [H-K'] color for all sources, as well as two-color and color-magnitude diagrams. The stellar populations inside and outside the clusters are similar, suggesting that these systems are rather evolved. Shock-driven H_2_ emission knots are also detected, which may be related to evident subclusters in an earlier evolutionary stage.
- ID:
- ivo://CDS.VizieR/J/AJ/140/1214
- Title:
- Near-IR spectroscopic survey of class I YSOs
- Short Name:
- J/AJ/140/1214
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a near-IR spectroscopic survey of 110 Class I protostars observed from 0.80um to 2.43um at a spectroscopic resolution of R=1200. This survey is unique in its selection of targets from the whole sky, its sample size, wavelength coverage, depth, and sample selection.
- ID:
- ivo://CDS.VizieR/J/AJ/135/2496
- Title:
- Near-IR survey of Class I protostars
- Short Name:
- J/AJ/135/2496
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the observational results of a near-infrared survey of a large sample of Class I protostars designed to determine the Class I binary separation distribution from ~100AU to ~5000AU. We have selected targets from a new sample of 267 nearby candidate Class I objects. This sample is well understood, consists of mostly Class I young stellar objects (YSOs) within 1kpc, has targets selected from the whole sky, and is not biased by previous studies of star formation.
- ID:
- ivo://CDS.VizieR/J/ApJS/206/9
- Title:
- New EGOs from Spitzer GLIMPSE II survey. I.
- Short Name:
- J/ApJS/206/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have produced a catalog containing 98 newly identified massive young stellar object (MYSO) candidates associated with ongoing outflows (known as extended green objects, or EGOs). These have been identified from the Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) II data set and our new identifications increase the number of known EGOs to ~400 in our Galaxy, adding to the ~300 previously identified EGOs reported by Cyganowski et al. (2008, Cat. J/AJ/136/2391) from the GLIMPSE I survey. The high detection rate (~70%) of 95 GHz class I methanol masers achieved in a survey toward 57 of these new EGOs with the Mopra 22m radio telescope demonstrates that the new EGOs are associated with outflows. Investigations of the mid-infrared properties and physical associations with other star formation tracers (e.g., infrared dark clouds, class I and II methanol masers, and millimeter Bolocam Galactic Plane Survey sources) reveal that the newly identified EGOs are very similar in nature to those in the sample of Cyganowski et al. All of the observational evidence supports the hypothesis that EGOs correspond to MYSOs at the earliest evolutionary stage, with ongoing outflow activity, and active rapid accretion.
- ID:
- ivo://CDS.VizieR/J/ApJS/206/22
- Title:
- Newly EGOs from GLIMPSE II survey. II. MoC
- Short Name:
- J/ApJS/206/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have undertaken a survey of molecular lines in the 3mm band toward 57 young stellar objects using the Australia Telescope National Facility Mopra 22m radio telescope. The target sources were young stellar objects with active outflows (extended green objects (EGOs)) newly identified from the GLIMPSE II survey. We observe a high detection rate (50%) of broad line wing emission in the HNC and CS thermal lines, which combined with the high detection rate of class I methanol masers toward these sources (reported in Paper I, Cat. J/ApJS/206/9) further demonstrates that the GLIMPSE II EGOs are associated with outflows. The physical and kinematic characteristics derived from the 3mm molecular lines for these newly identified EGOs are consistent with these sources being massive young stellar objects with ongoing outflow activity and rapid accretion. These findings support our previous investigations of the mid-infrared properties of these sources and their association with other star formation tracers (e.g., infrared dark clouds, methanol masers and millimeter dust sources) presented in Paper I. The high detection rate (64%) of the hot core tracer CH_3_CN reveals that the majority of these new EGOs have evolved to the hot molecular core stage. Comparison of the observed molecular column densities with predictions from hot core chemistry models reveals that the newly identified EGOs from the GLIMPSE II survey are members of the youngest hot core population, with an evolutionary time scale of the order of 10^3^yr.
- ID:
- ivo://CDS.VizieR/J/ApJS/196/4
- Title:
- New young star candidates in Taurus-Auriga
- Short Name:
- J/ApJS/196/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Taurus Molecular Cloud subtends a large solid angle on the sky, in excess of 250deg^2^. The search for legitimate Taurus members to date has been limited by sky coverage as well as the challenge of distinguishing members from field interlopers. The Wide-field Infrared Survey Explorer has recently observed the entire sky, and we take advantage of the opportunity to search for young stellar object (YSO) candidate Taurus members from a ~260deg^2^ region designed to encompass previously identified Taurus members. We use near- and mid-infrared colors to select objects with apparent infrared excesses and incorporate other catalogs of ancillary data to present a list of rediscovered Taurus YSOs with infrared excesses (taken to be due to circumstellar disks), a list of rejected YSO candidates (largely galaxies), and a list of 94 surviving candidate new YSO-like Taurus members. There is likely to be contamination lingering in this candidate list, and follow-up spectra are warranted.
