- ID:
- ivo://CDS.VizieR/J/A+A/584/A91
- Title:
- Catalog of dense cores in Aquila from Herschel
- Short Name:
- J/A+A/584/A91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present and discuss the results of the Herschel Gould Belt survey (HGBS) observations in an ~11deg^2^ area of the Aquila molecular cloud complex at d~260pc, imaged with the SPIRE and PACS photometric cameras in parallel mode from 70-micron to 500-micron. Using the multi-scale, multi-wavelength source extraction algorithm getsources, we identify a complete sample of starless dense cores and embedded (Class 0-I) protostars in this region, and analyze their global properties and spatial distributions. We find a total of 651 starless cores, ~60% +/-10% of which are gravitationally bound prestellar cores, and they will likely form stars in the future. We also detect 58 protostellar cores. The core mass function (CMF) derived for the large population of prestellar cores is very similar in shape to the stellar initial mass function (IMF), confirming earlier findings on a much stronger statistical basis and supporting the view that there is a close physical link between the stellar IMF and the prestellar CMF. The global shift in mass scale observed between the CMF and the IMF is consistent with a typical star formation efficiency of ~40% at the level of an individual core. By comparing the numbers of starless cores in various density bins to the number of young stellar objects (YSOs), we estimate that the lifetime of prestellar cores is ~1Myr, which is typically ~4 times longer than the core free-fall time, and that it decreases with average core density. We find a strong correlation between the spatial distribution of prestellar cores and the densest filaments observed in the Aquila complex. About 90% of the Herschel-identified prestellar cores are located above a background column density corresponding to A_V_~7, and ~75% of them lie within filamentary structures with supercritical masses per unit length >~16M_{sun}_/pc. These findings support a picture wherein the cores making up the peak of the CMF (and probably responsible for the base of the IMF) result primarily from the gravitational fragmentation of marginally supercritical filaments. Given that filaments appear to dominate the mass budget of dense gas at A_V_>7, our findings also suggest that the physics of prestellar core formation within filaments is responsible for a characteristic "efficiency" SFR/M_dense_~5+/-2x10^-8^yr^-1^ for the star formation process in dense gas.
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- ID:
- ivo://CDS.VizieR/J/A+A/638/A74
- Title:
- Catalog of dense cores in Oph molecular cloud
- Short Name:
- J/A+A/638/A74
- Date:
- 02 Mar 2022 11:56:27
- Publisher:
- CDS
- Description:
- Herschel observations of nearby clouds in the Gould Belt support a paradigm for low-mass star formation, starting with the generation of molecular filaments, followed by filament fragmentation, and the concentration of mass into self-gravitating prestellar cores. With the unique far-infrared and submillimeter continuum imaging capabilities of the Herschel Space observatory, the closeby (d=139pc) Ophiuchus cloud was mapped at five wavelengths from 70 microns to 500 microns with the aim of providing a complete census of dense cores in this region, including unbound starless cores, bound prestellar cores, and protostellar cores. Taking advantage of the high dynamic range and multi-wavelength nature of the Herschel data, we used the multi-scale decomposition algorithms getsources and getfilaments to identify a complete sample of dense cores and filaments in the cloud and study their properties. The densest clouds of the Ophiuchus complex, L1688 and L1689, which thus far are only indirectly described as filamentary regions owing to the spatial distribution of their young stellar objects (YSOs), are confirmed to be dominated by filamentary structures. The tight correlation observed between prestellar cores and filamentary structures in L1688 and L1689 supports the view that solar-type star formation occurs primarily in dense filaments. While the sub clouds of the complex show disparities, L1689 being less efficient than L1688 at forming stars when considering their total mass budgets, both sub clouds share almost the same prestellar core formation efficiency in dense molecular gas. We also find evidence in the Herschel data for a remarkable concentric geometrical configuration in L1688 which is dominated by up to three arc-like compression fronts and presumably created by shockwave events emanating from the Sco OB2 association, including the neighboring massive (O9V) star sigma Sco.
- ID:
- ivo://CDS.VizieR/J/A+A/635/A34
- Title:
- Catalog of dense cores in Orion B from Herschel
- Short Name:
- J/A+A/635/A34
- Date:
- 14 Jan 2022 08:07:23
- Publisher:
- CDS
- Description:
- We present a detailed study of the Orion B molecular cloud complex (d~400pc), which was imaged with the PACS and SPIRE photometric cameras at wavelengths from 70-micron to 500-micron as part of the Herschel Gould Belt survey (HGBS). We release new high-resolution maps of column density and dust temperature for the whole complex, derived in the same consistent manner as for other HGBS regions. In the filamentary subregions NGC2023 and 2024, NGC2068 and 2071, and L1622, a total of 1768 starless dense cores were identified based on Herschel data, 490-804 (~28-45%) of which are self-gravitating prestellar cores that will likely form stars in the future. A total of 76 protostellar dense cores were also found. The typical lifetime of the prestellar cores was estimated to be t_pre_^OrionB^=1.7(-0.6/+0.8)Myr. The prestellar core mass function (CMF) derived for the whole sample of prestellar cores peaks at ~0.5Msun (in dN/dlogM format) and is consistent with a power-law with logarithmic slope -1.27+/-0.24 at the high-mass end, compared to the Salpeter slope of -1.35. In the Orion B region, we confirm the existence of a transition in prestellar core formation efficiency (CFE) around a fiducial value A_V_^bg^~7mag in background visual extinction, which is similar to the trend observed with Herschel in other regions, such as the Aquila cloud. This is not a sharp threshold, however, but a smooth transition between a regime with very low prestellar CFE at A_V_^bg^<5 and a regime with higher, roughly constant CFE at A_V_^bg^>~10. The total mass in the form of prestellar cores represents only a modest fraction (~20%) of the dense molecular cloud gas above A_V_^bg^>~7mag. About 60-80% of the prestellar cores are closely associated with filaments, and this fraction increases up to >90% when a more complete sample of filamentary structures is considered. Interestingly, the median separation observed between nearest core neighbors corresponds to the typical inner filament width of ~0.1pc, which is commonly observed in nearby molecular clouds, including Orion B. Analysis of the CMF observed as a function of background cloud column density shows that the most massive prestellar cores are spatially segregated in the highest column density areas, and suggests that both higher- and lower-mass prestellar cores may form in denser filaments.
- ID:
- ivo://CDS.VizieR/J/ApJ/627/621
- Title:
- Catalog of Extremely Red Objects
- Short Name:
- J/ApJ/627/621
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use a serendipitously discovered overdensity of extremely red objects (EROs) to study the morphologies and cumulative surface number density of EROs in a dense environment. Our extremely deep imaging allows us to select very faint EROs, reaching K_S_=21, or ~2mag fainter than the L* of passively evolving ellipticals at z=1.5.
- ID:
- ivo://CDS.VizieR/J/A+A/515/A42
- Title:
- Catalog of high extinction clouds
- Short Name:
- J/A+A/515/A42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The earliest phases of massive star formation are found in cold and dense infrared dark clouds (IRDCs). Since the detection method of IRDCs is very sensitive to the local properties of the background emission, we present here an alternative method to search for high column density in the Galactic plane by using infrared extinction maps. We find clouds between 1 and 5kpc, of which many were missed by previous surveys. By studying the physical conditions of a subsample of these clouds, we aim at a better understanding of the initial conditions of massive star formation. We made extinction maps of the Galactic plane based on the 3.6-4.5 microns color excess between the two shortest wavelength Spitzer IRAC bands, reaching to visual extinctions of ~100mag and column densities of 9x10^22^cm^-2^. From this we compiled a new sample of cold and compact high extinction clouds. We used the MAMBO array at the IRAM 30m telescope to study the morphology, masses, and densities of the clouds and the dense clumps within them. The latter were followed up by pointed ammonia observations with the 100m Effelsberg telescope to determine rotational temperatures and kinematic distances. Extinction maps of the Galactic plane trace large scale structures such as the spiral arms. The extinction method probes lower column densities, N(H_2)~4x10^22^cm^-2^, than the 1.2mm continuum, which reaches up to N(H_2)~3x10^23^cm^-2^ but is less sensitive to large scale structures. The 1.2mm emission maps reveal that the high extinction clouds contain extended cold dust emission, from filamentary structures to still diffuse clouds. Most of the clouds are dark in 24 microns, but several show already signs of star formation via maser emission or bright infrared sources, suggesting that the high extinction clouds contain a variety of evolutionary stages. The observations suggest an evolutionary scheme from dark, cold and diffuse clouds, to clouds with a stronger 1.2mm peak and to finally clouds with many strong 1.2mm peaks, which are also warmer, more turbulent, and already have some star formation signposts.
- ID:
- ivo://CDS.VizieR/J/PASP/132/E4301
- Title:
- Catalog of Infrared Dark Clouds
- Short Name:
- J/PASP/132/E4301
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The field of computer vision has greatly matured in the past decade, and many of the methods and techniques can be useful for astronomical applications. One example is in searching large imaging surveys for objects of interest, especially when it is difficult to specify the characteristics of the objects being searched for. We have developed a method using contour finding and convolution neural networks (CNNs) to search for Infrared Dark Clouds (IRDCs) in the Spitzer Galactic plane survey data. IRDCs can vary in size, shape, orientation, and optical depth, and are often located near regions with complex emission from molecular clouds and star formation, which can make the IRDCs difficult to reliably identify. False positives can occur in regions where emission is absent, rather than from a foreground IRDC. The contour finding algorithm we implemented found most closed figures in the mosaic and we developed rules to filter out some of the false positive before allowing the CNNs to analyze them. The method was applied to the Spitzer data in the Galactic plane surveys, and we have constructed a catalog of IRDCs which includes additional parts of the Galactic plane that were not included in earlier surveys.
- ID:
- ivo://CDS.VizieR/II/225
- Title:
- Catalog of Infrared Observations, Edition 5
- Short Name:
- II/225
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Catalog of Infrared Observations and its associated data base comprise a summary of infrared astronomical observations published in the scientific literature from 1965 through 1997 in the wavelength range 1 micrometer - 1 mm. The database contains infrared observational data for sources outside the Solar System, constructed through a search of the most active scientific journals, IR surveys and catalogs. To date, about 6200 journal articles and 10 major survey catalogs have been included in the data base, which contains 374,653 individual observations of about 62,000 different infrared sources. More than 8,000 of these sources are identifiable with visible objects. The bibliographical files link observations in the catalog with the original articles published in the literature. References give the standard information plus full titles. The Index of Infrared Source Positions is ordered alphabetically by source name and can be used to quickly locate sources in the position-ordered catalog. For sources with no published IR source position, a nominal position may have been given based on other sources. Nominal positions are usually the best available, but not necessarily the true IR positions. Nominal position references are indicated in the index.
- ID:
- ivo://CDS.VizieR/II/216
- Title:
- Catalog of Infrared Observations, Edition 4 (CIO)
- Short Name:
- II/216
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Catalog of Infrared Observations and its associated data base comprise a summary of infrared astronomical observations published in the scientific literature from 1965 through 1995 in the wavelength range 1 micrometer - 1 mm. The database contains infrared observational data for sources outside the Solar System, constructed through a search of the most active scientific journals, IR surveys and catalogs. To date, about 6195 journal articles and 10 major survey catalogs have been included in the data base, which contains more than 325,000 individual observations of about 55,000 different infrared sources. More than 8,000 of these sources are identifiable with visible objects. The bibliographical files link observations in the catalog with the original articles published in the literature. References give the standard information plus full titles. The Index of Infrared Source Positions is ordered alphabetically by source name and can be used to quickly locate sources in the position-ordered catalog. For sources with no published IR source position, a nominal position may have been given based on other sources. Nominal positions are usually the best available, but not necessarily the true IR positions. Nominal position references are indicated in the index.
- ID:
- ivo://CDS.VizieR/I/270
- Title:
- Catalog of Positions of IR Stellar Sources (CPIRSS)
- Short Name:
- I/270
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The U.S. Naval Observatory Catalog of Positions of Infrared Stellar Sources (CPIRSS) was originally compiled in 1994 to provide astrometry at the sub-arcsecond level for many of the point sources in the 1987 version of the IRAS Point Source Catalog (NASA RP-1190). This was accomplished by the identification of IRAS sources with bright optical stars, checked by requiring the color V-[12] (with [12] being a magnitude derived from the IRAS flux) to be consistent with the optical colors or spectral type. Additionally, the K magnitude (2.2 microns) has been estimated. This version, completed in 2001, contains 37,700 stars and includes the Hipparcos and Tycho-2 astrometry and photometry which was unavailable at the time of the original compilation.
- ID:
- ivo://CDS.VizieR/J/MNRAS/382/412
- Title:
- Catalog of SDSS-DR5/2MASS spectroscopic quasars
- Short Name:
- J/MNRAS/382/412
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 13444 SDSS-DR5 spectroscopic quasars which have an 2MASS near-IR counterpart within 5" of their position.