- ID:
- ivo://CDS.VizieR/J/A+A/527/A62
- Title:
- HK photometry in an UCHII region near Sh2-217
- Short Name:
- J/A+A/527/A62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study stars and gas in and around the HII region Sh 2-217 to see if the various physical parameters derived from the data (such as column densities, masses, sizes, and timescales) are consistent with the predictions of a simple model of the collect-and-collapse mechanism. This should indicate whether stars forming in molecular gas at the borders of the HII region could have been triggered by the expansion of the ionized gas. We observed the emission of various molecules and transitions towards Sh 2-217, and obtained both near-infrared photometry in the H and K bands, and near-infrared images in [FeII] and H2 narrow-band filters of the stars in a molecular condensation at the edge of the HII region, where an UC HII region is also located.
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- ID:
- ivo://CDS.VizieR/J/A+A/485/155
- Title:
- HK photometry of rho Oph PMS stars
- Short Name:
- J/A+A/485/155
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Variability is a common characteristic of pre-main-sequence stars (PMS). Near-IR variability surveys of young stellar objects (YSOs) can probe stellar and circumstellar environments and provide information about the dynamics of the ongoing magnetic and accretion processes. Furthermore, variability can be used as a tool to uncover new cluster members in star formation regions. We hope to achieve the deepest near-IR variability study of YSOs targeting the rho Ophiuchi cluster. Fourteen epochs of observations were obtained with the Wide Field Camera (WFCAM) at the UKIRT telescope scheduled in a manner that allowed the study of variability on timescales of days, months, and years. Statistical tools, such as the multi-band cross correlation index and the reduced chi-square, were used to disentangle signals of variability from noise. Variability characteristics are compared to existing models of YSOs in order to relate them to physical processes, and then used to select new candidate members of this star-forming region. Variability in the near-IR is found to be present in 41% of the known population of rho Ophiuchi recovered in our sample. The behaviours shown are several and can be associated with the existence of spots on the stellar surface, variations in circumstellar extinction, or changes in the geometry of an accretion disc. Using variability, a new population of objects has been uncovered, that is believed to be part of the rho Ophiuchi cluster.
- ID:
- ivo://CDS.VizieR/J/A+A/501/563
- Title:
- HKs photometry in the Arches cluster
- Short Name:
- J/A+A/501/563
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The massive Arches cluster near the Galactic center should be an ideal laboratory for investigating massive star formation under extreme conditions. But it comes at a high price: the cluster is hidden behind several tens of magnitudes of visual extinction. Severe crowding requires space or AO-assisted instruments to resolve the stellar populations, and even with the best instruments interpreting the data is far from direct. Several investigations using NICMOS and the most advanced AO imagers on the ground revealed an overall top-heavy IMF for the cluster, with a very flat IMF near the center. There are several effects, however, that could potentially bias these results, in particular the strong differential extinction and the problem of transforming the observations into a standard photometric system in the presence of strong reddening. We present new observations obtained with the NAOS-Conica (NACO) AO-imager on the VLT. The problem of photometric transformation is avoided by working in the natural photometric system of NACO, and we use a Bayesian approach to determine masses and reddenings from the broad-band IR colors. A global value of Gamma=-1.1+/-0.2 for the high-mass end (M>10M_{sun}_) of the IMF is obtained, and we conclude that a power law of Salpeter slope cannot be discarded for the Arches cluster. The flattening of the IMF towards the center is confirmed, but is less severe than previously thought. We find Gamma=-0.88+/-0.20, which is incompatible with previous determinations. Within 0.4pc we derive a total mass of ~2.0(+/-0.6)x10^4^M_{sun}_ for the cluster and a central mass density rho=2(+/-0.4)x10^5^M_{sun}_/pc^3^ that confirms Arches as the densest known young massive cluster in the Milky Way.
- ID:
- ivo://CDS.VizieR/J/AJ/112/1188
- Title:
- HK survey emission-line candidates
- Short Name:
- J/AJ/112/1188
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a list of 218 additional candidate emission-line objects discovered with the northern and southern HK interference-filter/ objective-prism survey of Beers and collaborators. The objects have apparent magnitudes in the range 10<=B<=16, several magnitudes fainter than obtained with previous prism surveys of similar resolution. Of the new candidates, 73 have been previously identified. The total list of HK-survey emission-line candidates now numbers 376 objects, 104 of which were noted by previous surveys.
- ID:
- ivo://CDS.VizieR/J/AJ/108/268
- Title:
- HK survey emission-line candidates positions
- Short Name:
- J/AJ/108/268
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents a list of 158 candidate emission-line objects detected with the northern HK interference-filter/objective-prism survey obtained with the Burrell Schmidt telescope. The objects have magnitudes in the range 11=<B=<15.5, several magnitudes fainter than obtained with prism surveys of similar resolution. (The HK filter restricts the passband to the region around the H and K lines of Ca II)
- ID:
- ivo://CDS.VizieR/J/ApJS/168/277
- Title:
- HK-Survey field horizontal-branch candidates
- Short Name:
- J/ApJS/168/277
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present coordinates and available photometric information (either from previous or recent broadband UBV observations, and near-infrared photometry from the 2MASS Point Source Catalog) for 12,056 stars (11,516 of which are unique) identified in the HK Survey of Beers and colleagues as candidate field horizontal-branch or A-type stars. These stars, in the apparent magnitude range 10<=B<=16.0, were selected using an objective-prism/interference-filter survey technique. The availability of 2MASS information permits assembly of a cleaned version of this catalog, comprising likely blue horizontal-branch (BHB) stars or blue stragglers in the color interval [-0.2<=(B-V)_0_<=+0.2].
- ID:
- ivo://archive.stsci.edu/catalogs/HLASTARCLUSTERS
- Title:
- HLA Star Clusters ConeSearch
- Short Name:
- STARCLUSTERS CS
- Date:
- 13 Feb 2020 17:47:36
- Publisher:
- Space Telescope Science Institute Archive
- Description:
- All MAST catalog holdings are available via a ConeSearch endpoint. A high-level science product was produced cataloging star clusters within the HLA: compact star cluster catalogs are presented for 20 nearby, star-forming galaxies using observations from the Advanced Catalog for Surveys (ACS) and source lists generated by the Hubble Legacy Archive. Results based on these cluster catalogs are published in the paper "The Luminosity Function of Star Clusters in 20 Star-Forming Galaxies Based on Hubble Legacy Archive Photometry" Whitmore, AJ 147:78. A typical cluster luminosity function can be approximated by a power-law, with an average value for the index of -2.37 and rms scatter = 0.18. The uniform database provided by these HLA catalogs results in a small scatter (0.5 magnitude) in the correlation between the magnitude of the brightest cluster (M_brightest) and Log of the number of clusters brighter than M_I = -9 (Log N). More information on the catalog is available at https://archive.stsci.edu/prepds/hlastarclusters/. All available missions are listed at http://archive.stsci.edu/vo/mast_services.html.
- ID:
- ivo://CDS.VizieR/J/ApJS/244/16
- Title:
- HLF photometric catalog in GOODS-S v2.0
- Short Name:
- J/ApJS/244/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This manuscript describes the public release of the Hubble Legacy Fields (HLF) project photometric catalog for the extended GOODS-South region from the Hubble Space Telescope (HST) archival program AR-13252. The analysis is based on the version 2.0 HLF data release that now includes all ultraviolet (UV) imaging, combining three major UV surveys. The HLF data combines over a decade worth of 7475 exposures taken in 2635 orbits totaling 6.3Ms with the HST Advanced Camera for Surveys Wide Field Channel (ACS/WFC) and the Wide Field Camera 3 (WFC3) UVIS/IR Channels in the greater GOODS-S extragalactic field, covering all major observational efforts (e.g., GOODS, GEMS, CANDELS, ERS, UVUDF, and many other programs; see Illingworth+ arXiv:1606.00841). The HLF GOODS-S catalogs include photometry in 13 bandpasses from the UV (WFC3/UVIS F225W, F275W, and F336W filters), optical (ACS/WFC F435W, F606W, F775W, F814W and F850LP filters), to near-infrared (WFC3/IR F098M, F105W, F125W, F140W and F160W filters). Such a data set makes it possible to construct the spectral energy distributions (SEDs) of objects over a wide wavelength range from high-resolution mosaics that are largely contiguous. Here, we describe a photometric analysis of 186474 objects in the HST imaging at wavelengths 0.2-1.6{mu}m. We detect objects from an ultra-deep image combining the PSF-homogenized and noise-equalized F850LP, F125W, F140W, and F160W images, including Gaia astrometric corrections. SEDs were determined by carefully taking the effects of the point-spread function in each observation into account.
6429. HLock01-LAB 2D spectrum
- ID:
- ivo://CDS.VizieR/J/A+A/629/A23
- Title:
- HLock01-LAB 2D spectrum
- Short Name:
- J/A+A/629/A23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of HLock01-LAB, a luminous and large Ly{alpha} nebula at z=3.326. Medium-band imaging and long-slit spectroscopic observations with the Gran Telescopio Canarias reveal extended emission in the Ly{alpha} 1215{AA}, CIV 1550{AA}, and HeII 1640{AA} lines over ~100kpc, and a total luminosity L(Ly{alpha})=(6.4+/-0.1)x10^44^erg/s. HLock01-LAB presents an elongated morphology aligned with two faint radio sources contained within the central ~8kpc of the nebula. The radio structures are consistent with faint radio jets or lobes of a central galaxy, whose spectrum shows nebular emission characteristic of a type-II active galactic nucleus (AGN). The continuum emission of the AGN at short wavelengths is however likely dominated by stellar emission of the host galaxy, for which we derive a stellar mass M*~2.3x10^11^M_{sun}_. Our kinematic analysis shows that the ionized gas is perturbed almost exclusively in the inner region between the radio structures, probably as a consequence of jet-gas interactions, whereas in the outer regions the ionized gas appears more quiescent. The detection of extended emission in CIV and CIII] indicates that the gas within the nebula is not primordial. Feedback may have enriched the halo at at least 50kpc from the nuclear region. Using rest-frame UV emission-line diagnostics, we find that the gas in the nebula is likely heated by the AGN. Nevertheless, at the center of the nebula we find extreme emission line ratios of Ly{alpha}/CIV~60 and Ly{alpha}/HeII~80, one of the highest values measured to date, and well above the standard values of photoionization models (Ly{alpha}/HeII ~30 for case B photoionization). Our data suggest that jet-induced shocks are likely responsible for the increase of the electron temperature and, thus, the observed Ly{alpha} enhancement in the center of the nebula. This scenario is further supported by the presence of radio structures and perturbed kinematics in this region. The large Ly{alpha} luminosity in HLock01-LAB is likely due to a combination of AGN photoionization and jet-induced shocks, highlighting the diversity of sources of energy powering Ly{alpha} nebulae. Future follow-up observations of HLock01-LAB will help to reveal the finer details of the excitation conditions of the gas induced by jets and to investigate the underlying cooling and feedback processes in this unique object.
- ID:
- ivo://CDS.VizieR/J/A+A/644/A120
- Title:
- HL TAU and IRAS04302+2247 H2CS ALMA images
- Short Name:
- J/A+A/644/A120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Planet formation starts around Sun-like protostars with ages <=1Myr, but the chemical compositions of the surrounding discs remains unknown. We aim to trace the radial and vertical spatial distribution of a key species of S-bearing chemistry, namely H_2_CS, in protoplanetary discs. We also aim to analyse the observed distributions in light of the H_2_CS binding energy in order to discuss the role of thermal desorption in enriching the gas disc component. In the context of the ALMA chemical survey of disk-outflow sources in the Taurus star forming region (ALMA-DOT), we observed five Class I or early Class II sources with the o-H_2_CS(7_1,6_-6_1,5_) line. ALMA-Band 6 was used, reaching spatial resolutions ~=40au, that is, Solar System spatial scales. We also estimated the binding energy of H2CS using quantum mechanical calculations, for the first time, for an extended, periodic, crystalline ice. We imaged H2CS emission in two rotating molecular rings in the HL Tau and IRAS04302+2247 discs, the outer radii of which are ~140au (HL Tau) and 115 au (IRAS 04302+2247). The edge-on geometry of IRAS 04302+2247 allows us to reveal that H2CS emission peaks at radii of 60-115au, at z=+/-50au from the equatorial plane. Assuming LTE conditions, the column densities are 10^14^cm^-2^. We estimate upper limits of a few 10^13^cm^-2^ for the H2CS column densities in DG Tau, DG Tau B, and Haro 6-13 discs. For HL Tau, we derive, for the first time, the [H_2_CS]/[H] abundance in a protoplanetary disc (~10^-14^). The binding energy of H2CS computed for extended crystalline ice and amorphous ices is 4258K and 3000-4600K, respectively, implying thermal evaporation where dust temperatures are 50-80K. H_2_CS traces the so-called warm molecular layer, a region previously sampled using CS and H_2_CO. Thioformaldehyde peaks closer to the protostar than H_2_CO and CS, plausibly because of the relatively high excitation level of the observed 7_1,6_-6_1,5_ line (60K). The H_2_CS binding energy implies that thermal desorption dominates in thin, au-sized, inner and/or upper disc layers, indicating that the observed H2CS emitting up to radii larger than 100au is likely injected in the gas phase due to non-thermal processes.