- ID:
- ivo://CDS.VizieR/J/MNRAS/399/1506
- Title:
- IRDC cores in SCUBA Legacy Catalogue
- Short Name:
- J/MNRAS/399/1506
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an investigation of candidate infrared dark cloud (IRDC) cores as identified by Simon et al. (2006, Cat. J/ApJ/639/227) located within the Submillimetre Common User Bolometer Array (SCUBA) Legacy Catalogue. After applying a uniform noise cut to the catalogue data, we identify 154 IRDC cores that were detected at 850um and 51 cores that were not. We derive column densities for each core from their 8um extinction and find that the IRDCs detected at 850um have higher column densities (a mean of 1.7x10^22^cm^-2^) compared to those cores not detected at 850um (a mean of 1.0x10^22^cm-2).
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/658/1264
- Title:
- IR-excess sources in GLIMPSE and MSX
- Short Name:
- J/ApJ/658/1264
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have identified 230 Tycho-2 Spectral Catalog stars that exhibit 8um mid-IR extraphotospheric excesses in the MSX and Spitzer GLIMPSE surveys. Of these, 183 are either OB stars earlier than B8 in which the excess plausibly arises from a thermal bremsstrahlung component or evolved stars in which the excess may be explained by an atmospheric dust component. The remaining 47 stars have spectral classifications B8 or later and appear to be main-sequence or late pre-main-sequence objects harboring circumstellar disks. Six of the 47 stars exhibit multiple signatures characteristic of pre-main-sequence circumstellar disks, including emission lines, near-IR K-band excesses, and X-ray emission. Approximately one-third of the remaining 41 sources have emission lines suggesting relative youth. We modeled the excesses in 26 stars having two or more measurements in excess of the expected photospheres as single-component blackbodies.
- ID:
- ivo://CDS.VizieR/J/A+A/474/883
- Title:
- ISOSS J23053+5953 maps
- Short Name:
- J/A+A/474/883
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Due to the short timescales involved and observational difficulties, our knowledge of the earliest phases of massive star formation remains incomplete. We aim to explore the physical conditions during the initial phases of high-mass star formation and to detect a genuine massive (mass M>8M_{sun}_) protostar at an early evolutionary stage.
- ID:
- ivo://CDS.VizieR/J/ApJ/817/167
- Title:
- JCMT Gould Belt Survey: dense cores in Orion B
- Short Name:
- J/ApJ/817/167
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a first look at the SCUBA-2 observations of three sub-regions of the Orion B molecular cloud: LDN 1622, NGC 2023/2024, and NGC 2068/2071, from the JCMT Gould Belt Legacy Survey. We identify 29, 564, and 322 dense cores in L1622, NGC 2023/2024, and NGC 2068/2071 respectively, using the SCUBA-2 850{mu}m map, and present their basic properties, including their peak fluxes, total fluxes, and sizes, and an estimate of the corresponding 450{mu}m peak fluxes and total fluxes, using the FellWalker source extraction algorithm. Assuming a constant temperature of 20K, the starless dense cores have a mass function similar to that found in previous dense core analyses, with a Salpeter-like slope at the high-mass end. The majority of cores appear stable to gravitational collapse when considering only thermal pressure; indeed, most of the cores which have masses above the thermal Jeans mass are already associated with at least one protostar. At higher cloud column densities, above 1-2x10^23^/cm2, most of the mass is found within dense cores, while at lower cloud column densities, below 1x10^23^/cm2, this fraction drops to 10% or lower. Overall, the fraction of dense cores associated with a protostar is quite small (<8%), but becomes larger for the densest and most centrally concentrated cores. NGC 2023/2024 and NGC 2068/2071 appear to be on the path to forming a significant number of stars in the future, while L1622 has little additional mass in dense cores to form many new stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/448/1551
- Title:
- JCMT Gould Belt Survey: Serpens MWC 297
- Short Name:
- J/MNRAS/448/1551
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present SCUBA-2 450 and 850{mu}m observations of the Serpens MWC 297 region, part of the James Clerk Maxwell Telescope (JCMT) Gould Belt Survey of nearby star-forming regions. Simulations suggest that radiative feedback influences the star formation process and we investigate observational evidence for this by constructing temperature maps. Maps are derived from the ratio of SCUBA-2 fluxes and a two-component model of the JCMT beam for a fixed dust opacity spectral index of {beta}=1.8. Within 40-arcsec of the B1.5Ve Herbig star MWC 297, the submillimetre fluxes are contaminated by free-free emission with a spectral index of 1.03+/-0.02, consistent with an ultracompact HII region and polar winds/jets. Contamination accounts for 73+/-5 per cent and 82+/-4 per cent of peak flux at 450{mu}m and 850 {mu}m, respectively. The residual thermal disc of the star is almost undetectable at these wavelengths. Young stellar objects (YSOs) are confirmed where SCUBA-2 850{mu}m clumps identified by the fellwalker algorithm coincide with Spitzer Gould Belt Survey detections. We identify 23 objects and use T_bol_ to classify nine YSOs with masses 0.09 to 5.1M_{sun}_. We find two Class 0, one Class 0/I, three Class I and three Class II sources. The mean temperature is 15+/-2K for the nine YSOs and 32+/-4K for the 14 starless clumps. We observe a starless clump with an abnormally high mean temperature of 46+/-2K and conclude that it is radiatively heated by the star MWC 297. Jeans stability provides evidence that radiative heating by the star MWC 297 may be suppressing clump collapse.
- ID:
- ivo://CDS.VizieR/J/MNRAS/461/4022
- Title:
- JCMT Gould Belt Survey: Southern Orion A
- Short Name:
- J/MNRAS/461/4022
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the JCMT Gould Belt Survey's first look results of the southern extent of the Orion A Molecular Cloud ({delta}<=-5:31:27.5). Employing a two-step structure identification process, we construct individual catalogues for large-scale regions of significant emission labelled as islands and smaller-scale subregions called fragments using the 850{mu}m continuum maps obtained using SCUBA-2. We calculate object masses, sizes, column densities, and concentrations. We discuss fragmentation in terms of a Jeans instability analysis and highlight interesting structures as candidates for follow-up studies. Furthermore, we associate the detected emission with young stellar objects (YSOs) identified by Spitzer and Herschel. We find that although the population of active star-forming regions contains a wide variety of sizes and morphologies, there is a strong positive correlation between the concentration of an emission region and its calculated Jeans instability. There are, however, a number of highly unstable subregions in dense areas of the map that show no evidence of star formation. We find that only ~72 per cent of the YSOs defined as Class 0+I and flat-spectrum protostars coincide with dense 850{mu}m emission structures (column densities >3.7x10^21^cm^-2^). The remaining 28 per cent of these objects, which are expected to be embedded in dust and gas, may be misclassified. Finally, we suggest that there is an evolution in the velocity dispersion of YSOs such that sources which are more evolved are associated with higher velocities.
- ID:
- ivo://CDS.VizieR/J/MNRAS/460/4150
- Title:
- JCMT Gould Belt Survey: W40 complex
- Short Name:
- J/MNRAS/460/4150
- Date:
- 14 Jan 2022 11:14:19
- Publisher:
- CDS
- Description:
- We present SCUBA-2 450{mu}m and 850{mu}m observations of the W40 complex in the Serpens-Aquila region as part of the James Clerk Maxwell Telescope (JCMT) Gould Belt Survey (GBS) of nearby star-forming regions. We investigate radiative heating by constructing temperature maps from the ratio of SCUBA-2 fluxes using a fixed dust opacity spectral index, {beta}=1.8, and a beam convolution kernel to achieve a common 14.8-arcsec resolution. We identify 82 clumps ranging between 10 and 36K with a mean temperature of 20+/-3K. Clump temperature is strongly correlated with proximity to the external OB association and there is no evidence that the embedded protostars significantly heat the dust. We identify 31 clumps that have cores with densities greater than 10^5^cm^-3^. 13 of these cores contain embedded Class 0/I protostars. Many cores are associated with bright-rimmed clouds seen in Herschel 70{mu}m images. From JCMT HARP observations of the ^12^CO 3-2 line, we find contamination of the 850{mu}m band of up to 20 per cent. We investigate the free-free contribution to SCUBA-2 bands from large-scale and ultracompact HII regions using archival VLA data and find the contribution is limited to individual stars, accounting for 9 per cent of flux per beam at 450{mu}m or 12 per cent at 850{mu}m in these cases. We conclude that radiative heating has potentially influenced the formation of stars in the Dust Arc sub-region, favouring Jeans stable clouds in the warm east and fragmentation in the cool west.
- ID:
- ivo://CDS.VizieR/J/MNRAS/469/2163
- Title:
- JCMT Plane Survey. first complete data release
- Short Name:
- J/MNRAS/469/2163
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first data release of the James Clerk Maxwell Telescope Plane Survey (JPS), the JPS Public Release 1. JPS is an 850-{mu}m continuum survey of six fields in the northern inner Galactic plane in a longitude range of l=7{deg}-63{deg}, made with the Submillimetre Common-User Bolometer Array 2. This first data release consists of emission maps of the six JPS regions with an average pixel-to-pixel noise of 7.19mJy/beam, when smoothed over the beam, and a compact source catalogue containing 7813 sources. The 95 per cent completeness limits of the catalogue are estimated at 0.04Jy/beam and 0.3Jy for the peak and integrated flux densities, respectively. The emission contained in the compact source catalogue is 42+/-5 per cent of the total and, apart from the large-scale (greater than 8 arcmin) emission, there is excellent correspondence with features in the 500-{mu}m Herschel maps. We find that, with two-dimensional matching, 98 {\pm} 2 per cent of sources within the fields centred at l=20{deg}, 30{deg}, 40{deg} and 50{deg} are associated with molecular clouds, with 91+/-3 per cent of the l=30{deg} and 40{deg} sources associated with dense molecular clumps. Matching the JPS catalogue to Herschel 70-{mu}m sources, we find that 38+/-1 per cent of sources show evidence of ongoing star formation. The JPS Public Release 1 images and catalogue will be a valuable resource for studies of star formation in the Galaxy and the role of environment and spiral arms in the star formation process.
- ID:
- ivo://CDS.VizieR/J/MNRAS/453/4264
- Title:
- JCMT Plane Survey: l=30{deg} field
- Short Name:
- J/MNRAS/453/4264
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present early results from the JCMT (James Clerk Maxwell Telescope) Plane Survey (JPS), which has surveyed the northern inner Galactic plane between longitudes l=7{deg} and l=63{deg} in the 850-{mu}m continuum with SCUBA-2 (Submm Common-User Bolometer Array 2), as part of the JCMT Legacy Survey programme. Data from the l=30{deg} survey region, which contains the massive-star-forming regions W43 and G29.96, are analysed after approximately 40 percent of the observations had been completed. The pixel-to-pixel noise is found to be 19mJy/beam after a smooth over the beam area, and the projected equivalent noise levels in the final survey are expected to be around 10mJy/beam. An initial extraction of compact sources was performed using the FellWalker method, resulting in the detection of 1029 sources above a 5{sigma} surface-brightness threshold. The completeness limits in these data are estimated to be around 0.2Jy/beam (peak flux density) and 0.8 Jy (integrated flux density) and are therefore probably already dominated by source confusion in this relatively crowded section of the survey. The flux densities of extracted compact sources are consistent with those of matching detections in the shallower APEX (Atacama Pathfinder Experiment) Telescope Large Area Survey of the Galaxy (ATLASGAL) survey. We analyse the virial and evolutionary state of the detected clumps in the W43 star-forming complex and find that they appear younger than the Galactic-plane average.
- ID:
- ivo://CDS.VizieR/J/MNRAS/469/492
- Title:
- JCMT/SCUBA2 objects in COSMOS and UDS fields
- Short Name:
- J/MNRAS/469/492
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present physical properties [redshifts (z), star-formation rates (SFRs) and stellar masses (M*)] of bright (S_850_>=4mJy) submm galaxies in the ~=2deg^2^ COSMOS and UDS fields selected with SCUBA-2/JCMT. We complete the galaxy identification process for all (~=2000) S/N>=3.5 850-{mu}m sources, but focus our scientific analysis on a high-quality subsample of 651 S/N>=4 sources with complete multiwavelength coverage including 1.1-mm imaging. We check the reliability of our identifications, and the robustness of the SCUBA-2 fluxes by revisiting the recent ALMA follow-up of 29 sources in our sample. Considering >4mJy ALMA sources, our identification method has a completeness of ~=86 per cent with a reliability of ~=92 per cent, and only ~=15-20 per cent of sources are significantly affected by multiplicity (when a secondary component contributes >1/3 of the primary source flux). The impact of source blending on the 850-{mu}m source counts as determined with SCUBA-2 is modest; scaling the single-dish fluxes by ~=0.9 reproduces the ALMA source counts. For our final SCUBA-2 sample, we find median z=2.40^+0.10^_-0.04_, SFR=287+/-6M_{sun}_/yr and log(M*/M_{sun)_=11.12+/-0.02 (the latter for 349/651 sources with optical identifications). These properties clearly locate bright submm galaxies on the high-mass end of the 'main sequence' of star-forming galaxies out to z~= 6, suggesting that major mergers are not a dominant driver of the high-redshift submm-selected population. Their number densities are also consistent with the evolving galaxy stellar mass function. Hence, the submm galaxy population is as expected, albeit reproducing the evolution of the main sequence of star-forming galaxies remains a challenge for theoretical models/simulations.