- ID:
- ivo://CDS.VizieR/J/A+A/606/A35
- Title:
- Barnard 1b-N and 1b-S 350GHz images
- Short Name:
- J/A+A/606/A35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The formation epoch of protostellar disks is debated because of the competing roles of rotation, turbulence, and magnetic fields in the early stages of low-mass star formation. Magnetohydrodynamics simulations of collapsing cores predict that rotationally supported disks may form in strongly magnetized cores through ambipolar diffusion or misalignment between the rotation axis and the magnetic field orientation. Detailed studies of individual sources are needed to cross check the theoretical predictions. We present 0.06-0.1arcsec resolution images at 350GHz toward B1b-N and B1b-S, which are young class 0 protostars, possibly first hydrostatic cores. The images have been obtained with ALMA, and we compare these data with magnetohydrodynamics simulations of a collapsing turbulent and magnetized core. The submillimeter continuum emission is spatially resolved by ALMA. Compact structures with optically thick 350GHz emission are detected toward both B1b-N and B1b-S, with 0.2 and 0.35arcsec radii (46 and 80au at the Perseus distance of 230pc), within a more extended envelope. The flux ratio between the compact structure and the envelope is lower in B1b-N than in B1b-S, in agreement with its earlier evolutionary status. The size and orientation of the compact structure are consistent with 0.2arcsec resolution 32GHz observations obtained with the Very Large Array as a part of the VANDAM survey, suggesting that grains have grown through coagulation. The morphology, temperature, and densities of the compact structures are consistent with those of disks formed in numerical simulations of collapsing cores. Moreover, the properties of B1b-N are consistent with those of a very young protostar, possibly a first hydrostatic core. These observations provide support for the early formation of disks around low-mass protostars.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/612/A79
- Title:
- Barnard 30 dark cloud IR and submm data
- Short Name:
- J/A+A/612/A79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The early evolutionary stage of brown dwarfs (BDs) is not very well characterized, especially during the embedded phase. Our goal is to gain insight into the dominant formation mechanism of very low-mass objects and BDs. We have conducted deep observations at 870um obtained with the LABOCA bolometer at the APEX telescope in order to identify young submillimeter (submm) sources in the Barnard 30 dark cloud. We have complemented these data with multi-wavelength observations from the optical to the far-IR and compiled complete spectral energy distributions in order to identify the counterparts, characterize the sources and to assess their membership to the association and stellar or substellar status based on the available photometric information. We have identified 34 submm sources and a substantial number of possible and probable Barnard 30 members within each individual APEX/LABOCA beam. They can be classified into three distinct groups. First, 15 of these 34 have a clear optical or IR counterpart to the submm peak and nine of them are potential proto-BD candidates. Moreover, a substantial number of them could be multiple systems. A second group of 13 sources comprises candidate members with significant infrared excesses located away from the central submm emission. All of them include BD candidates, some displaying IR excess, but their association with submm emission is unclear. In addition, we have found six starless cores and, based on the total dust mass estimate, three might be pre-substellar (or pre-BDs) cores. Finally, the complete characterization of our APEX/LABOCA sources, focusing on those detected at 24 and/or 70um, indicates that in our sample of 34 submm sources there are, at least: two WTTs, four CTTs, five young stellar objects, eight proto-BD candidates (with another three dubious cases), and one very low luminosity objects.
- ID:
- ivo://CDS.VizieR/J/MNRAS/473/4731
- Title:
- Barred galaxies structural decomposition
- Short Name:
- J/MNRAS/473/4731
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of two-component (disc+bar) and three-component (disc+bar+bulge) multiwavelength 2D photometric decompositions of barred galaxies in five Sloan Digital Sky Survey (SDSS) bands (ugriz). This sample of ~3500 nearby (z<0.06) galaxies with strong bars selected from the Galaxy Zoo citizen science project is the largest sample of barred galaxies to be studied using photometric decompositions that include a bar component. With detailed structural analysis, we obtain physical quantities such as the bar- and bulge-to-total luminosity ratios, effective radii, Sersic indices and colours of the individual components. We observe a clear difference in the colours of the components, the discs being bluer than the bars and bulges. An overwhelming fraction of bulge components have Sersic indices consistent with being pseudo-bulges. By comparing the barred galaxies with a mass-matched and volume-limited sample of unbarred galaxies, we examine the connection between the presence of a large-scale galactic bar and the properties of discs and bulges. We find that the discs of unbarred galaxies are significantly bluer compared to the discs of barred galaxies, while there is no significant difference in the colours of the bulges. We find possible evidence of secular evolution via bars that leads to the build-up of pseudo-bulges and to the quenching of star formation in the discs. We identify a subsample of unbarred galaxies with an inner lens/oval and find that their properties are similar to barred galaxies, consistent with an evolutionary scenario in which bars dissolve into lenses. This scenario deserves further investigation through both theoretical and observational work.
- ID:
- ivo://CDS.VizieR/J/MNRAS/439/1749
- Title:
- Barred S0 galaxies in the Coma cluster
- Short Name:
- J/MNRAS/439/1749
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This study uses r-band images from the Eighth Data Release of the Sloan Digital Sky Survey (SDSS DR8) to study bars in lenticular (S0) galaxies in one of the nearest rich cluster environments, the Coma cluster. We develop techniques for bar detection and assess their success when applied to SDSS image data. To detect and characterize bars, we perform 2D bulge+disc+bar light decompositions of galaxy images with galfit. Using a sample of artificial galaxy images, we determine the faintest magnitude at which bars can be successfully measured at the depth and resolution of SDSS. We perform detailed decompositions of 83 S0 galaxies in Coma, 64 from a central sample, and 19 from a cluster outskirt sample. For the central sample, the S0 bar fraction is 72^+5^_-6_%. This value is significantly higher than that obtained using an ellipse-fitting method for bar detection, 48^+6^_-6_%. At a fixed luminosity, barred S0s are redder in g-r colour than unbarred S0s by 0.02mag. The frequency and strength of bars increase towards fainter luminosities. Neither central metallicity nor stellar age distributions differ significantly between barred and unbarred S0s. There is an increase in the bar fraction towards the cluster core, but this is at a low significance level. Bars have at most a weak correlation with cluster-centric radius.
- ID:
- ivo://CDS.VizieR/J/ApJ/870/31
- Title:
- BAT AGN spectroscopic survey. XI. IR photometry
- Short Name:
- J/ApJ/870/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We quantify the luminosity contribution of active galactic nuclei (AGNs) to the 12{mu}m, mid-infrared (MIR; 5-38{mu}m), and total IR (5-1000{mu}m) emission in the local AGNs detected in the all-sky 70 month Swift/Burst Alert Telescope (BAT) ultrahard X-ray survey. We decompose the IR spectral energy distributions (SEDs) of 587 objects into the AGN and starburst components using templates for an AGN torus and a star-forming galaxy. This enables us to recover the emission from the AGN torus including the low-luminosity end, down to log(L_14-150_/erg/s)~41, which typically has significant host galaxy contamination. The sample demonstrates that the luminosity contribution of the AGN to the 12{mu}m, the MIR, and the total IR bands is an increasing function of the 14-150keV luminosity. We also find that for the most extreme cases, the IR pure-AGN emission from the torus can extend up to 90{mu}m. The total IR AGN luminosity obtained through the IR SED decomposition enables us to estimate the fraction of the sky obscured by dust, i.e., the dust covering factor. We demonstrate that the median dust covering factor is always smaller than the median X-ray obscuration fraction above an AGN bolometric luminosity of log(L_bol_^(AGN)^/erg/s)~42.5. Considering that the X-ray obscuration fraction is equivalent to the covering factor coming from both the dust and gas, this indicates that an additional neutral gas component, along with the dusty torus, is responsible for the absorption of X-ray emission.
- ID:
- ivo://CDS.VizieR/J/AJ/141/99
- Title:
- BATC and SDSS photometry of A2589 cluster
- Short Name:
- J/AJ/141/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Smooth X-ray morphology and non-detection of a radio source at the center of A2589 indicate that it is a typical case of a well-relaxed regular galaxy cluster. In this paper, we present a multicolor photometry for A2589 (z=0.0414) with 15 intermediate bands in the Beijing-Arizona-Taiwan-Connecticut (BATC) system which covers an optical wavelength range from 3000{AA} to 10000{AA}. The spectral energy distributions (SEDs) for more than 5000 sources are achieved down to V~20mag in about a 1{deg}^2^ field. A2589 has also been covered by the Sloan Digital Sky Survey (SDSS) in photometric mode only. A cross-identification of the BATC-detected galaxies with the SDSS photometric catalog yields 1199 galaxies brighter than i=19.5mag, among which 68 member galaxies with known spectroscopic redshifts are found. After combining the SDSS five-band photometric data and the BATC SEDs, photometric redshift is applied to these galaxies to select faint member galaxies. The color-magnitude relation is taken as a further restriction of early-type cluster galaxies. As a result, 106 galaxies are newly selected as member galaxies.
- ID:
- ivo://CDS.VizieR/II/262
- Title:
- BATC Data Release One - BATC DR1
- Short Name:
- II/262
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Multi-color photometry data of the project, "Large Field Multi-Color Sky Survey" supported by Beijing-Arizona-Taiwan-Connecticut (BATC) is presented. From 1995 to 2004, 110 58'x58' sky survey fields have been observed. First release of BATC catalog includes observation results for 511842 sources located in 70 sky survey fields. The whole release is divided into 70 files. Each file corresponds to one observation field. The BATC filter system includes 15 intermediate band filters, covering a range in optical wavelengths from 300 to 1000 nm. The telescope used is a 60/90 cm f/3 Schmidt telescope located at Xinglong Station of National Astronomical Observatories. A Ford Aerospace 2048x2048 CCD camera with 15 micron pixel size is mounted at the Schmidt focus of the telescope. The field of view of the CCD is 58'x58' with a plate scale of 1.7arcsec per pixel. The BATC magnitude system adopts the AB magnitude system, defining as M_batc_ = -2.5log(F_{nu}_) - 48.60 where F_{nu}_ is the flux per unit frequency in units of erg/s/cm^2^/Hz, and F_{nu}_={Sum}[d(log{nu})*f_{nu}_*R_{nu}_]/{Sum}[d(log{nu})*R_{nu}_] where R_{nu}_ represents the response of the system. Four Oke & Gunn (1983ApJ...266..713O) standards, HD 19445, HD 84937, BD+26 2606 and BD+17 4708 are observed in photometric nights for flux calibration. We provide catalogues down to i-band (666nm) about 20 mag with complete spectral energy distributions (SEDs) for each object. Typical error in photometry is about 0.02-0.05 mag. There is usually the deepest observation at i-band. Most of the catalogs use i-band data as their reference for coordinate calibration. While, "T0329","TA01" and "TA03" use j-band as reference. All colors in the "TA04" catalog have no photo calibration. For detailed information of the data reduction, please refer to: Zhou, X., Jiang, Z., Ma, J., et al. 2003, 2003A&A...397..361Z
- ID:
- ivo://CDS.VizieR/J/other/RAA/10.1
- Title:
- BATC photometry in A98 cluster
- Short Name:
- J/other/RAA/10.1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An optical photometric observation with the Beijing-Arizona-Taiwan-Connecticut (BATC) multicolor system is carried out for A98 (z=0.104), a galaxy cluster with two large enhancements in X-ray surface brightness. Spectral energy distributions (SEDs) covering 15 intermediate bands are obtained for all sources detected down to V~20mag in a field of 58'x58'. After star-galaxy separation with color-color diagrams, a photometric redshift technique is applied to the galaxy sample for further membership determination. The color-magnitude relation is taken as a further restriction of the early-type cluster galaxies. As a result, a list of 198 faint member galaxies is achieved. Based
- ID:
- ivo://CDS.VizieR/J/AJ/131/2245
- Title:
- BATC photometry of SN2004dj
- Short Name:
- J/AJ/131/2245
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometric data of the Type II-P supernova (SN) 2004dj in NGC 2403. The multicolor light curves cover the SN from 60 to 200 days after explosion and are measured with a set of intermediate-band filters that have the advantage of tracing the strength variations of some spectral features.
- ID:
- ivo://CDS.VizieR/J/other/RAA/12.1381
- Title:
- BATC photometry on A119
- Short Name:
- J/other/RAA/12.1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents multicolor optical photometry of the nearby galaxy cluster Abell 119 (z=0.0442) with the Beijing-Arizona-Taiwan-Connecticut system of 15 intermediate bands. Within the BATC field of view of 58'x58', there are 368 galaxies with known spectroscopic redshifts, including 238 member galaxies (called sample I). Based on the spectral energy distributions of 1376 galaxies brighter than i_BATC_=19.5, the photometric redshift technique and the color-magnitude relation of early-type galaxies are applied to select faint member galaxies. As a result, 117 faint galaxies were selected as new member galaxies. Combined with sample I, an enlarged sample (called sample II) of 355 member galaxies is obtained. Spatial distribution and localized velocity structure for two samples demonstrate that A119 is a dynamically complex cluster with at least three prominent substructures in the central region within 1Mpc. A large velocity dispersion for the central clump indicates a merging along the line of sight. No significant evidence for morphology or luminosity segregations is found in either sample. With the PEGASE evolutionary synthesis model, the environmental effect on the properties of star formation is confirmed. Faint galaxies in the low-density region tend to have longer time scales of star formation, smaller mean stellar ages, and lower metallicities in their interstellar medium, which is in agreement with the context of the hierarchical cosmological scenario.
