- ID:
- ivo://CDS.VizieR/J/ApJS/165/307
- Title:
- Survey for ionization in neutral gas galaxies. I.
- Short Name:
- J/ApJS/165/307
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We introduce the Survey for Ionization in Neutral Gas Galaxies (SINGG), a census of star formation in HI-selected galaxies. The survey consists of H{alpha} and R-band imaging of a sample of 468 galaxies selected from the HI Parkes All Sky Survey (HIPASS). The sample spans three decades in HI mass and is free of many of the biases that affect other star-forming galaxy samples. We present the criteria for sample selection, list the entire sample, discuss our observational techniques, and describe the data reduction and calibration methods. This paper focuses on 93 SINGG targets whose observations have been fully reduced and analyzed to date.
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- ID:
- ivo://CDS.VizieR/J/ApJ/661/801
- Title:
- Survey for ionization in neutral gas galaxies. III.
- Short Name:
- J/ApJ/661/801
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the first data release from the Survey for Ionization in Neutral-Gas Galaxies (SINGG) H{alpha} survey of HI-selected galaxies to study the quantitative behavior of the diffuse, warm ionized medium (WIM) across the range of properties represented by these 109 galaxies.
- ID:
- ivo://CDS.VizieR/J/AJ/109/2503
- Title:
- Synthesis model in HII regions. II.
- Short Name:
- J/AJ/109/2503
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A stellar population synthesis model, suitable for comparison with Giant Extragalactic H II Regions (GEHRs), is constructed incorporating the recent developments in modeling stellar evolution by Maeder and co-workers and stellar atmospheres by Kurucz. A number of quantities suitable for comparison with broadband data of GEHRs in visible and near-infrared parts of the spectrum are synthesized in addition to the hydrogen and helium ionizing photon production rates at solar metallicities, for three scenarios of star formation - (i) instantaneous burst (IB); (ii) continuous star formation (CSF); and (iii) two bursts of star formation, with the older burst rich in red supergiants. For the IB case, evolution of color indexes shows three distinct phases - an initial steady blue phase, followed by a red bump (5-15Myr) and another steady phase with color indexes intermediate to the earlier two phases. CSF color indexes asymptotically reach peak values at ~10Myr, never reaching the reddest IB color indexes. Ionizing photon production rate falls off by an order of magnitude in 6Myr for IB, whereas it almost remains constant for the CSF model. Two-burst models with burst separations ~10Myr have properties of both IB and CSF, simultaneously producing the red IB color indexes and high ionizing photon rate, making such regions easily distinguishable using optical observations. Flat IMFs result in bluest color indexes when the massive stars are on the main sequence and reddest color indexes during the red supergiant phase of the evolving massive stars. Errors on the computed quantities due to the statistical uncertainties inherent in the process of star formation become negligible for cluster masses in excess of 10^5 M_{sun}_. Our GEHR spectra in the range 200nm to 3um are found to be in good agreement with the computations of Mas-Hesse & Kunth (1991A&AS...88..399M)
- ID:
- ivo://CDS.VizieR/J/ApJ/696/1278
- Title:
- The extended star-forming environment of M17
- Short Name:
- J/ApJ/696/1278
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- M17 is one of the youngest and most massive nearby star-formation regions in the Galaxy. It features a bright HII region erupting as a blister from the side of a giant molecular cloud (GMC). Combining photometry from the Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) with complementary infrared (IR) surveys, we identify candidate young stellar objects (YSOs) throughout a 1.5x1{deg} field that includes the M17 complex. The long sightline through the Galaxy behind M17 creates significant contamination in our YSO sample from unassociated sources with similar IR colors. Removing contaminants, we produce a highly reliable catalog of 96 candidate YSOs with a high probability of association with the M17 complex. We fit model spectral energy distributions to these sources and constrain their physical properties. Extrapolating the mass function of 62 intermediate-mass YSOs (M_*_>3M_{sun}_), we estimate that >1000 stars are in the process of forming in the extended outer regions of M17. The remaining 34 candidate YSOs are found in a 0.17deg^2^ field containing the well-studied M17 HII region and photodissociation region (PDR), where bright diffuse mid-IR emission drastically reduces the sensitivity of the GLIMPSE point-source detections.
- ID:
- ivo://CDS.VizieR/J/ApJS/135/227
- Title:
- The FIRST bright quasar survey. III.
- Short Name:
- J/ApJS/135/227
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an extension of the FIRST Bright Quasar Survey (FBQS) to the South Galactic cap, and to a fainter optical magnitude limit. Radio source counterparts with SERC R magnitudes brighter than 18.9 which meet the other FBQS criteria are included. We supplement this list with a modest number of additional objects to test our completeness for quasars with extended radio morphologies. The survey covers 589deg^2^ in two equatorial strips in the southern cap. We have obtained spectra for 86% of the 522 candidates and find 321 radio-selected quasars of which 264 are reported here for the first time. A comparison of this fainter sample with the FBQS sample shows the two to be generally similar. Fourteen new broad absorption line (BAL) quasars are included in this sample. When combined with the previously identified BAL quasars in our earlier papers, we can discern a break in the frequency of BAL quasars with radio loudness, namely that the relative number of high-ionization BAL quasars drops by a factor of 4 for quasars with a radio-loudness parameter R*>100.
- ID:
- ivo://CDS.VizieR/J/AJ/160/242
- Title:
- The H{alpha} dots survey. II. 119 new dots
- Short Name:
- J/AJ/160/242
- Date:
- 09 Mar 2022 22:00:00
- Publisher:
- CDS
- Description:
- We present the second catalog of serendipitously discovered compact extragalactic emission-line sources-H{alpha} Dots. These objects have been discovered in searches of moderately deep narrow-band images acquired for the ALFALFA H{alpha} project. In addition to cataloging 119 new H{alpha} Dots, we also present follow-up spectral data for the full sample. These spectra allow us to confirm the nature of these objects as true extragalactic emission-line objects, to classify them in terms of activity type (star-forming or AGN), and to identify the emission line via which they were discovered. We tabulate photometric and spectroscopic data for the all objects, and we present an overview of the properties of the full H{alpha} Dot sample. The H{alpha} Dots represent a broad range of star-forming and active galaxies detected via several different emission lines over a wide range of redshifts. The sample includes H{alpha}-detected blue compact dwarf galaxies at low redshift, [OIII]-detected Seyfert 2 and Green Pea-like galaxies at intermediate redshifts, and QSOs detected via one of several UV emission lines, including Ly{alpha}. Despite the heterogeneous appearance of the resulting catalog of objects, we show that our selection method leads to well-defined samples of specific classes of emission-line objects with properties that allow for statistical studies of each class.
- ID:
- ivo://CDS.VizieR/J/ApJS/194/32
- Title:
- The HII Region Discovery Survey (HRDS). II.
- Short Name:
- J/ApJS/194/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Green Bank Telescope (GBT) HII Region Discovery Survey has doubled the number of known HII regions in the Galactic zone 343{deg}<=l<=67{deg} with |b|<=1{deg}. We detected 603 discrete hydrogen radio recombination line (RRL) components at 9GHz (3cm) from 448 targets. Our targets were selected based on spatially coincident mid-infrared and 20cm radio continuum emission. Such sources are almost invariably HII regions; we detected hydrogen RRL emission from 95% of our target sample. The sensitivity of the GBT and the power of its spectrometer together made this survey possible. Here, we provide a catalog of the measured properties of the RRL and continuum emission from the survey nebulae. The derived survey completeness limit, 180mJy at 9GHz, is sufficient to detect all HII regions ionized by single O-stars to a distance of 12kpc. We discovered 34 first quadrant negative-velocity HII regions, which lie at extreme distances from the Sun and appear to be part of the Outer Arm. We found RRL emission from 208 Spitzer GLIMPSE 8.0um "bubble" sources, 65 of which have been cataloged previously. It thus appears that nearly all GLIMPSE bubbles are HII regions and that ~50% of all Galactic HII regions have a bubble morphology at 8.0um.
- ID:
- ivo://CDS.VizieR/J/ApJS/213/1
- Title:
- The MSFRs Omnibus X-ray Catalog (MOXC)
- Short Name:
- J/ApJS/213/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Massive Star-forming Regions (MSFRs) Omnibus X-ray Catalog (MOXC), a compendium of X-ray point sources from Chandra/ACIS observations of a selection of MSFRs across the Galaxy, plus 30 Doradus in the Large Magellanic Cloud. MOXC consists of 20623 X-ray point sources from 12 MSFRs with distances ranging from 1.7kpc to 50kpc. Additionally, we show the morphology of the unresolved X-ray emission that remains after the cataloged X-ray point sources are excised from the ACIS data, in the context of Spitzer and WISE observations that trace the bubbles, ionization fronts, and photon-dominated regions that characterize MSFRs. In previous work, we have found that this unresolved X-ray emission is dominated by hot plasma from massive star wind shocks. This diffuse X-ray emission is found in every MOXC MSFR, clearly demonstrating that massive star feedback (and the several-million-degree plasmas that it generates) is an integral component of MSFR physics.
- ID:
- ivo://CDS.VizieR/J/ApJS/209/31
- Title:
- The MYStIX IR-Excess Source catalog (MIRES)
- Short Name:
- J/ApJS/209/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Massive Young Star-Forming Complex Study in Infrared and X-rays (MYStIX) project provides a comparative study of 20 Galactic massive star-forming complexes (d=0.4-3.6kpc). Probable stellar members in each target complex are identified using X-ray and/or infrared data via two pathways: X-ray detections of young/massive stars with coronal activity/strong winds or (2) infrared excess (IRE) selection of young stellar objects (YSOs) with circumstellar disks and/or protostellar envelopes. We present the methodology for the second pathway using Spitzer/IRAC, 2MASS, and UKIRT imaging and photometry. Although IRE selection of YSOs is well-trodden territory, MYStIX presents unique challenges. The target complexes range from relatively nearby clouds in uncrowded fields located toward the outer Galaxy (e.g., NGC 2264, the Flame Nebula) to more distant, massive complexes situated along complicated, inner Galaxy sightlines (e.g., NGC 6357, M17). We combine IR spectral energy distribution (SED) fitting with IR color cuts and spatial clustering analysis to identify IRE sources and isolate probable YSO members in each MYStIX target field from the myriad types of contaminating sources that can resemble YSOs: extragalactic sources, evolved stars, nebular knots, and even unassociated foreground/background YSOs. Applying our methodology consistently across 18 of the target complexes, we produce the MYStIX IRE Source (MIRES) Catalog comprising 20719 sources, including 8686 probable stellar members of the MYStIX target complexes. We also classify the SEDs of 9365 IR counterparts to MYStIX X-ray sources to assist the first pathway, the identification of X-ray-detected stellar members.
- ID:
- ivo://CDS.VizieR/J/ApJS/235/43
- Title:
- The 2nd MSFRs Omnibus X-ray Catalog (MOXC2)
- Short Name:
- J/ApJS/235/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the second installment of the Massive Star-forming Regions (MSFRs) Omnibus X-ray Catalog (MOXC2), a compilation of X-ray point sources detected in Chandra/ACIS observations of 16 Galactic MSFRs and surrounding fields. MOXC2 includes 13 ACIS mosaics, three containing a pair of unrelated MSFRs at different distances, with a total catalog of 18396 point sources. The MSFRs sampled range over distances of 1.3kpc to 6kpc and populations varying from single massive protostars to the most massive Young Massive Cluster known in the Galaxy. By carefully detecting and removing X-ray point sources down to the faintest statistically significant limit, we facilitate the study of the remaining unresolved X-ray emission. Through comparison with mid-infrared images that trace photon-dominated regions and ionization fronts, we see that the unresolved X-ray emission is due primarily to hot plasmas threading these MSFRs, the result of feedback from the winds and supernovae of massive stars. The 16 MSFRs studied in MOXC2 more than double the MOXC1 sample, broadening the parameter space of ACIS MSFR explorations and expanding Chandra's substantial contribution to contemporary star formation science.
