- ID:
- ivo://CDS.VizieR/J/A+A/595/A94
- Title:
- Temperature structures in Galactic center clouds
- Short Name:
- J/A+A/595/A94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Central Molecular Zone (CMZ) at the center of our Galaxy is the best template to study star formation processes under extreme conditions, similar to those in high-redshift galaxies. We observed on-the-fly maps of para-H_2_CO transitions at 218GHz and 291GHz with the Atacama Pathfinder Experiment (APEX) telescope towards seven Galactic center clouds. From the temperature-sensitive integrated intensity line ratios of H_2_CO(3_21_-2_20_)/H_2_CO(3_03_-2_02_) and H_2_CO(4_22_-3_21_)/H_2_CO(4_04_-3_03_) in combination with radiative transfer models, we produce gas temperature maps of our targets. Our targets have a complex velocity structure that requires a careful disentanglement of the different components. We produce temperature maps for each of the velocity components and show that the temperatures of the components differ, revealing temperature gradients in the clouds.
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- ID:
- ivo://CDS.VizieR/J/BaltA/20/317
- Title:
- TGU 619 stars spectral types and distances
- Short Name:
- J/BaltA/20/317
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Interstellar extinction is investigated in a 1.5 square degree area of the Cepheus Flare in the direction of the dark cloud TGU 619 at l=102.5{deg}, b=+15.5{deg} . The study is based on photometric classification of 658 stars in spectral and luminosity classes down to V=16mag using photometry in the Vilnius seven-color system published in Paper I (2009BaltA..18..161Z, Cat. J/BaltA/18/161). The extinction in the investigated area is very uneven: in the most transparent directions we find an extinction of 0.3-1.1mag while in the darkest directions the maximum extinction observed is 2.6mag. The real extinction should be considerably larger since in the direction of some cloud clumps no stars are seen. The distribution of stars in the AV vs. d plot gives evidence that the dust clouds are located at a distance of 286+/-20pc.
- ID:
- ivo://CDS.VizieR/J/BaltA/18/161
- Title:
- TGU 619 Vilnius photometry
- Short Name:
- J/BaltA/18/161
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog contains magnitudes and color indices of 1304 stars down to ~16.6mag in V measured in the seven-color Vilnius photometric system in the area of 1.5 square degrees with the center at Galactic coordinates 102.4{deg}, +15.5{deg}, containing the dark cloud TGU619 in the Cepheus Flare. For most of the stars spectral and luminosity classes determined from the photometric data are given.
- ID:
- ivo://CDS.VizieR/J/ApJ/786/37
- Title:
- The Auriga-California molecular cloud
- Short Name:
- J/ApJ/786/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observations of the Auriga-California Molecular Cloud (AMC) at 3.6, 4.5, 5.8, 8.0, 24, 70, and 160 {mu}m observed with the IRAC and MIPS detectors as part of the Spitzer Gould Belt Legacy Survey. The total mapped areas are 2.5 deg^2^ with IRAC and 10.47 deg^2^ with MIPS. This giant molecular cloud is one of two in the nearby Gould Belt of star-forming regions, the other being the Orion A Molecular Cloud (OMC). We compare source counts, colors, and magnitudes in our observed region to a subset of the SWIRE data that was processed through our pipeline. Using color-magnitude and color-color diagrams, we find evidence for a substantial population of 166 young stellar objects (YSOs) in the cloud, many of which were previously unknown. Most of this population is concentrated around the LkH{alpha} 101 cluster and the filament extending from it. We present a quantitative description of the degree of clustering and discuss the relative fraction of YSOs in earlier (Class I and F) and later (Class II) classes compared to other clouds. We perform simple SED modeling of the YSOs with disks to compare the mid-IR properties to disks in other clouds and identify 14 classical transition disk candidates. Although the AMC is similar in mass, size, and distance to the OMC, it is forming about 15-20 times fewer stars.
- ID:
- ivo://CDS.VizieR/J/A+A/357/1001
- Title:
- The {lambda}-Orionis ring in CO
- Short Name:
- J/A+A/357/1001
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The table shows clump parameters for 130 peaks in CO(J=1->0) emission detected in the Lambda-Orionis ring in the survey of Lang et al. (1998PASA...15...70L). The clumps were isolated using the Clumpfind algorithm of Williams et al. (1994, Cat. <J/ApJ/428/693>). They are ordered and labelled according to the relative brightness of the peak temperatures within them, so clump 1 contains the emission maximum, but not necessarily the maximum W(CO) or largest mass.
- ID:
- ivo://CDS.VizieR/J/ApJ/833/176
- Title:
- The magnetic field of L1544. I. NIR data
- Short Name:
- J/ApJ/833/176
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The magnetic field (B-field) of the starless dark cloud L1544 has been studied using near-infrared (NIR) background starlight polarimetry (BSP) and archival data in order to characterize the properties of the plane-of-sky B-field. NIR linear polarization measurements of over 1700 stars were obtained in the H band and 201 of these were also measured in the K band. The NIR BSP properties are correlated with reddening, as traced using the Rayleigh-Jeans color excess (H-M) method, and with thermal dust emission from the L1544 cloud and envelope seen in Herschel maps. The NIR polarization position angles change at the location of the cloud and exhibit their lowest dispersion there, offering strong evidence that NIR polarization traces the plane-of-sky B-field of L1544. In this paper, the uniformity of the plane-of-sky B-field in the envelope region of L1544 is quantitatively assessed. This allows evaluation of the approach of assuming uniform field geometry when measuring relative mass-to-flux ratios in the cloud envelope and core based on averaging of the radio Zeeman observations in the envelope, as done by Crutcher et al. (2009ApJ...692..844C). In L1544, the NIR BSP shows the envelope B-field to be significantly non-uniform and likely not suitable for averaging Zeeman properties without treating intrinsic variations. Deeper analyses of the NIR BSP and related data sets, including estimates of the B-field strength and testing how it varies with position and gas density, are the subjects of later papers in this series.
- ID:
- ivo://CDS.VizieR/J/ApJ/784/3
- Title:
- The PAWS catalogs of GMCs and islands in M51
- Short Name:
- J/ApJ/784/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using data from the PdBI Arcsecond Whirlpool Survey (PAWS), we have generated the largest extragalactic giant molecular cloud (GMC) catalog to date, containing 1507 individual objects. GMCs in the inner M51 disk account for only 54% of the total ^12^CO(1-0) luminosity of the survey, but on average they exhibit physical properties similar to Galactic GMCs. We do not find a strong correlation between the GMC size and velocity dispersion, and a simple virial analysis suggests that ~30% of GMCs in M51 are unbound. We have analyzed the GMC properties within seven dynamically motivated galactic environments, finding that GMCs in the spiral arms and in the central region are brighter and have higher velocity dispersions than inter-arm clouds. Globally, the GMC mass distribution does not follow a simple power-law shape. Instead, we find that the shape of the mass distribution varies with galactic environment: the distribution is steeper in inter-arm region than in the spiral arms, and exhibits a sharp truncation at high masses for the nuclear bar region. We propose that the observed environmental variations in the GMC properties and mass distributions are a consequence of the combined action of large-scale dynamical processes and feedback from high-mass star formation. We describe some challenges of using existing GMC identification techniques for decomposing the ^12^CO(1-0) emission in molecule-rich environments, such as M51's inner disk.
- ID:
- ivo://CDS.VizieR/J/A+A/487/253
- Title:
- The RMS survey: ^13^CO observations of YSOs
- Short Name:
- J/A+A/487/253
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- MSX names, positions, observational rms values and molecular line parameters obtained from Gaussian fits to all detected components made towards the RMS sample of massive young stellar object candidates located in the southern Galactic plane.
- ID:
- ivo://CDS.VizieR/J/A+A/646/A170
- Title:
- The Serpens filament 13CO, C18O and C17O datacubes
- Short Name:
- J/A+A/646/A170
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Serpens filament, a prominent elongated structure in a relatively nearby molecular cloud, is believed to be at an early evolutionary stage, so studying its physical and chemical properties can shed light on filament formation and early evolution. The main goal is to address the physical and chemical properties as well as dynamical state of the Serpens filament at a spatial resolution of ~0.07pc and a spectral resolution of ~0.1~km/s. We performed ^13^CO (1-0), C^18^O (1-0), C^17^O (1-0), ^13^CO (2-1), C^18^O (2-1), and C^17^O (2-1) imaging observations toward the Serpens filament with the IRAM-3 m and APEX telescopes. Widespread narrow ^13^CO (2-1) self-absorption is observed in this filament, causing the ^13^CO morphology to be different from the filamentary structure traced by C^18^O and C^17^O. Our excitation analysis suggests that the opacities of C^18^O transitions become higher than unity in most regions, and this analysis confirms the presence of widespread CO depletion. Further we show that the local velocity gradients have a tendency to be perpendicular to the filament's long axis in the outskirts and parallel to the large-scale magnetic field direction. The magnitudes of the local velocity gradients decrease toward the filament's crest. The observed velocity structure can be a result of gravity-driven accretion flows. The isochronic evolutionary track of the C^18^O freeze-out process indicates the filament is young with an age of <~2Myr. We propose that the Serpens filament is a newly-formed slightly-supercritical structure which appears to be actively accreting material from its ambient gas.
- ID:
- ivo://CDS.VizieR/J/AJ/150/40
- Title:
- The Spitzer c2d survey of clouds. XII. Perseus
- Short Name:
- J/AJ/150/40
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Spitzer Space Telescope mapped the Perseus molecular cloud complex with the Infrared Array Camera (IRAC) and the Multi-Band Imaging Photometer for Spitzer (MIPS) as part of the c2d Spitzer Legacy project. This paper combines the observations from both instruments giving an overview of low-mass star formation across Perseus from 3.6 to 70{mu}m. We provide an updated list of young stellar objects (YSOs) with new classifications and source fluxes from previous works, identifying 369 YSOs in Perseus with the Spitzer data set. By synthesizing the IRAC and MIPS maps of Perseus and building on the work of previous papers in this series, we present a current census of star formation across the cloud and within smaller regions. Sixty-seven percent of the YSOs are associated with the young clusters NGC 1333 and IC 348. The majority of the star formation activity in Perseus occurs in the regions around the clusters to the eastern and western ends of the cloud complex. The middle of the cloud is nearly empty of YSOs despite containing regions of high visual extinction. The western half of Perseus contains three-quarters of the total number of embedded YSOs (Class 0+I and Flat spectral energy distribution sources) in the cloud and nearly as many embedded YSOs as Class II and III sources. Class II and III objects greatly outnumber Class 0+I objects in eastern Perseus and IC 348. These results are consistent with previous age estimates for the clusters. Across the cloud, 56% of YSOs and 91% of the Class 0+I and Flat sources are in areas where A_v_>=5mag, indicating a possible extinction threshold for star formation.
