- ID:
- ivo://CDS.VizieR/J/ApJ/775/106
- Title:
- CANDELS passive and massive early-type galaxies
- Short Name:
- J/ApJ/775/106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the evolution of the number density, as a function of the size, of passive early-type galaxies (ETGs) with a wide range of stellar masses (10^10^M_{sun}_<M_*_<~10^11.5^M_{sun}_) from z~3 to z~1, exploiting the unique data set available in the GOODS-South field, including the recently obtained WFC3 images as part of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS). In particular, we select a sample of ~107 massive (M_*_>10^10^M_{sun}_), passive (SSFR<10^-2^/Gyr), and morphologically spheroidal galaxies at 1.2<z<3, taking advantage of the panchromatic data set available for GOODS, including VLT, CFHT, Spitzer, Chandra, and HST ACS+WFC3 data. We find that at 1<z<3 the passively evolving ETGs are the reddest and most massive objects in the universe, and we prove that a correlation between mass, morphology, color, and star formation activity is already in place at that epoch. We measure a significant evolution in the mass-size relation of passive ETGs from z~3 to z~1, with galaxies growing on average by a factor of two in size in a 3Gyr timescale only. We also witness an increase in the number density of passive ETGs of 50 times over the same time interval. We find that the first ETGs to form at z>~2 are all compact or ultra-compact, while normal-sized ETGs (meaning ETGs with sizes comparable to those of local counterparts of the same mass) are the most common ETGs only at z<1. The increase of the average size of ETGs at 0<z<1 is primarily driven by the appearance of new large ETGs rather than by the size increase of individual galaxies.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/497/330
- Title:
- Candidate main-sequence stars
- Short Name:
- J/ApJ/497/330
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Vega-like sources are main-sequence stars that exhibit IR fluxes in excess of expectations for stellar photospheres, most likely due to reradiation of stellar emission intercepted by orbiting dust grains. We have identified a large sample of main-sequence stars with possible excess IR radiation by cross-correlating the Michigan Catalog of Two-dimensional Spectral Types for the HD Stars with the IRAS Faint Source Survey Catalog. Some 60 of these Vega-like sources were not found during previous surveys of the IRAS database, the majority of which employed the lower sensitivity Point Source Catalog. Here, we provide details of our search strategy, together with a preliminary examination of the full sample of Vega-like sources.
- ID:
- ivo://CDS.VizieR/J/ApJ/751/22
- Title:
- Candidates of the {rho} Oph cluster
- Short Name:
- J/ApJ/751/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a general method for identifying the pre-main-sequence population of any star-forming region, unbiased with respect to the presence or absence of disks, in contrast to samples selected primarily via their mid-infrared emission from Spitzer surveys. We have applied this technique to a new, deep, wide-field, near-infrared imaging survey of the {rho} Ophiuchi cloud core to search for candidate low-mass members. In conjunction with published Spitzer IRAC photometry and least-squares fits of model spectra (COND, DUSTY, NextGen, and blackbody) to the observed spectral energy distributions, we have identified 948 candidate cloud members within our 90% completeness limits of J=20.0, H=20.0, and Ks=18.50. This population represents a factor of ~3 increase in the number of known young stellar objects in the {rho}} Ophiuchi cloud. A large fraction of the candidate cluster members (81%+/-3%) exhibit infrared excess emission consistent with the presence of disks, thus strengthening the possibility of their being bona fide cloud members. Spectroscopic follow-up will confirm the nature of individual objects, better constrain their parameters, and allow an initial mass function to be derived.
- ID:
- ivo://CDS.VizieR/J/A+A/330/505
- Title:
- Carbon stars IR emission
- Short Name:
- J/A+A/330/505
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectroscopic and photometric data relative to a sample of 55 carbon stars showing the 11.3{mu}m feature have been fitted in the wavelength range between 0.4 and 100{mu}m by means of a radiative transfer model using the laboratory extinction spectra of amorphous carbon and silicon carbide (SiC) grains. The transfer code allows to determine in a self-consistent way the grain equilibrium temperature of the various species at different distances from the central star and gives all the relevant circumstellar parameters which can be very important for the evolutionary study of carbon stars. In order to get meaningful information on the nature and physical properties of the dust grains responsible for the 11.3{mu}m feature and the underlying continuum, the fitting procedure of the spectr a has been applied individually to every single source. For this reason it has been possible to take into account any variation in position and shape of the band from source to source. Our analysis show that all the sources, in addition to the amorphous carbon grains accounting for the continuum emission, need always the presence of {alpha}-SiC particles while some of them require also {beta}-SiC. Moreover, the presence of one or both types of SiC particles seems not correlated neither with the total optical thickness nor with any other physical and geometrical parameters of the circumstellar envelope. The best-fit parameters found in this work have been used to calculate the mass-loss rate from the central stars. The clear correlation, that we find between the strength of the SiC feature and the total mass loss-rate, confirms the results already found by other authors for the same kind of sources and derived from the observed CO emission lines.
- ID:
- ivo://CDS.VizieR/J/ApJ/640/603
- Title:
- Catalog of AGNs in the GOODS fields
- Short Name:
- J/ApJ/640/603
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present mid-infrared observations of active galactic nuclei (AGNs) in the GOODS fields, performed with the Spitzer Space Telescope. These are the deepest infrared and X-ray fields to date and cover a total area of 0.1{deg}^2^. AGNs are selected on the basis of their hard (28keV) X-ray emission.
- ID:
- ivo://CDS.VizieR/J/MNRAS/411/373
- Title:
- Catalog of AKARI Deep Field South
- Short Name:
- J/MNRAS/411/373
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The AKARI Deep Field-South (ADF-S) is a ~12deg^2^ region near the South Ecliptic Pole that has been observed with deep scans in the far-infrared by the AKARI satellite. As such it is becoming one of the key extragalactic survey fields. We here present complementary observations of the ADF-S conducted by the Spitzer Space Telescope at wavelengths of 24 and 70um. We extract source catalogues at each of these wavelengths reaching depths of ~0.2mJy at 24um and ~20mJy at 70um. We also apply a K-to-24um colour criterion to select objects with galaxy-like colours in the 24-um survey. Completeness corrections as a function of flux density are derived for both catalogues by injecting artificial sources of known flux density into the maps, and we find that our surveys are 50 per cent complete at 0.26 and 24mJy at 24 and 70um, respectively.
- ID:
- ivo://CDS.VizieR/J/MNRAS/424/2442
- Title:
- Catalog of bubbles from Milky Way Project
- Short Name:
- J/MNRAS/424/2442
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalogue of 5106 infrared bubbles created through visual classification via the online citizen science website The Milky Way Project. Bubbles in the new catalogue have been independently measured b at least five individuals, producing consensus parameters for their position, radius, thickness, eccentricity and position angle. Citizen scientists - volunteers recruited online and taking part in this research - have independently rediscovered the locations of at least 86 percent of three widely used catalogues of bubbles and HII regions whilst finding an order of magnitude more objects. 29 per cent of the Milky Way Project catalogue bubbles lie on the rim of a larger bubble, or have smaller bubbles located within them, opening up the possibility of better statistical studies of triggered star formation. Also outlined is the creation of a heat map of star formation activity in the Galactic plane. This online resource provides a crowd-sourced map of bubbles and arcs in the Milky Way, and will enable better statistical analysis of Galactic star formation sites.
- 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.
- 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.