- ID:
- ivo://CDS.VizieR/J/ApJ/762/25
- Title:
- The most metal-poor stars in HES and SDSS. I.
- Short Name:
- J/ApJ/762/25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of 34 stars in the Hamburg/ESO Survey (HES) for metal-poor stars and the Sloan Digital Sky Survey (SDSS) that have [Fe/H]<~-3.0. Their median and minimum abundances are [Fe/H]=-3.1 and -4.1, respectively, while 10 stars have [Fe/H]<-3.5. High-resolution, high signal-to-noise spectroscopic data --equivalent widths and radial velocities-- are presented for these stars, together with an additional four objects previously reported or currently being investigated elsewhere. We have determined the atmospheric parameters, effective temperature (T_eff_), and surface gravity (logg), which are critical in the determination of the chemical abundances and the evolutionary status of these stars. Three techniques were used to derive these parameters. Spectrophotometric fits to model atmosphere fluxes were used to derive T_eff_, logg, and an estimate of E(B-V); H{alpha}, H{beta}, and H{gamma} profile fitting to model atmosphere results provided the second determination of T_eff_and logg; and finally, we used an empirical T_eff_-calibrated H{delta} index, for the third, independent T_eff_determination. The three values of T_eff_ are in good agreement, although the profile fitting may yield systematically cooler T_eff_values, by ~100K. This collective data set will be analyzed in future papers in the present series to utilize the most metal-poor stars as probes of conditions in the early universe.
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- 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/193/26
- Title:
- The M33 synoptic stellar survey. I.
- Short Name:
- J/ApJS/193/26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a ground-based BVI synoptic survey of the Local Group galaxy M33 which covers most of its disk and spans a period of 7 years. The survey targets luminous, long-period variables such as Cepheids and Miras and combines images from the DIRECT project and follow-up observations at the WIYN 3.5m telescope. This paper, the first in a series, presents the discovery and characterization of 564 Cepheid variables, which represent a factor of two increase over previous samples with calibrated point-spread function (PSF) photometry. We also describe the details of the observations and analysis of the survey data, including the use of archival Hubble Space Telescope images to characterize biases in our ground-based PSF photometry.
- ID:
- ivo://CDS.VizieR/J/AJ/153/170
- Title:
- The M33 Synoptic Stellar Survey. II. Mira variables
- Short Name:
- J/AJ/153/170
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of 1847 Mira candidates in the Local Group galaxy M33 using a novel semi-parametric periodogram technique coupled with a random forest classifier. The algorithms were applied to ~2.4*10^5^ I-band light curves previously obtained by the M33 Synoptic Stellar Survey. We derive preliminary period-luminosity relations at optical, near-infrared, and mid-infrared wavelengths and compare them to the corresponding relations in the Large Magellanic Cloud.
- ID:
- ivo://CDS.VizieR/J/ApJ/709/611
- Title:
- The multi-component absorber QSO 0318-0600
- Short Name:
- J/ApJ/709/611
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high spectral resolution Very Large Telescope observations of the broad absorption line quasar SDSS J0318-0600. This high-quality data set allows us to extract accurate ionic column densities and determine an electron number density of n_e_=10^3.3+/-0.2^cm^-3^ for the main outflow absorption component. The heavily reddened spectrum of SDSS J0318-0600 requires purely silicate dust with a reddening curve characteristic of predominately large grains, from which we estimate the bolometric luminosity. We carry out photoionization modeling to determine the total column density, ionization parameter, and distance of the gas and find that the photoionization models suggest abundances greater than solar. Due to the uncertainty in the location of the dust extinction, we arrive at two viable distances for the main ouflow component from the central source, 6 and 17kpc, where we consider the 6kpc location as somewhat more physically plausible. Assuming the canonical global covering of 20% for the outflow and a distance of 6kpc, our analysis yields a mass flux of 120M_{sun}_/yr and a kinetic luminosity that is ~0.1% of the bolometric luminosity of the object. Should the dust be part of the outflow, then these values are ~4x larger. The large mass flux and kinetic luminosity make this outflow a significant contributor to active galactic nucleus feedback processes.
- ID:
- ivo://CDS.VizieR/J/ApJS/249/32
- Title:
- The Multi-INstrument Burst ARchive (MINBAR)
- Short Name:
- J/ApJS/249/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the largest sample of type I (thermonuclear) X-ray bursts yet assembled, comprising 7083 bursts from 85 bursting sources. The sample is drawn from observations with Xenon-filled proportional counters on the long-duration satellites RXTE, BeppoSAX, and International Gamma-Ray Astrophysics Laboratory between 1996 February 8 and 2012 May 3. The burst sources were drawn from a comprehensive catalog of 115 burst sources, assembled from earlier catalogs and the literature. We carried out a consistent analysis for each burst light curve (normalized to the relative instrumental effective area) and provide measurements of rise time, peak intensity, burst timescale, and fluence. For bursts observed with the RXTE/PCA and BeppoSAX/Wide Field Camera we also provide time-resolved spectroscopy, including estimates of bolometric peak flux and fluence, and spectral parameters at the peak of the burst. For 950 bursts observed with the PCA from sources with previously detected burst oscillations, we include an analysis of the high time resolution data, providing information on the detectability and amplitude of the oscillations, as well as where in the burst they are found. We also present analysis of 118,848 observations of the burst sources within the sample time frame. We extracted 3-25keV X-ray spectra from most observations, and (for observations meeting our signal-to-noise criterion) we provide measurements of the flux, spectral colors, and, for selected sources, the position on the color-color diagram, for the best-fit spectral model. We present a description of the sample, a summary of the science investigations completed to date, and suggestions for further studies.
- ID:
- ivo://CDS.VizieR/J/ApJ/846/93
- Title:
- The multiplicity of M dwarfs in young moving groups
- Short Name:
- J/ApJ/846/93
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We image 104 newly identified low-mass (mostly M-dwarf) pre-main sequence (PMS) members of nearby young moving groups (YMGs) with Magellan Adaptive Optics (MagAO) and identify 27 stellar binaries with instantaneous projected separation as small as 40mas. Fifteen were previously unknown. The total number of multiple systems in this sample including spectroscopic and visual binaries from the literature is 36, giving a raw stellar multiplicity rate of at least 35_-4_^+5^% for this population. In the separation range of roughly 1-300au in which infrared AO imaging is most sensitive, the raw multiplicity rate is at least 24_-4_^+5^% for binaries resolved by the MagAO infrared camera (Clio). The M-star subsample of 87 stars yields a raw multiplicity of at least 30_-4_^+5^% over all separations, 21_-4_^+5^% for secondary companions resolved by Clio from 1 to 300au (23_-4_^+5^% for all known binaries in this separation range). A combined analysis with binaries discovered by the Search for Associations Containing Young stars shows that stellar multiplicity fraction as a function of mass over the range of 0.2 to 1.2M_{sun}_ appears to be linearly flat, in contrast to the field, where multiplicity increases with mass. After bias corrections are applied, the multiplicity of low-mass YMG members (0.2-0.6M_{sun}_) is in excess of the field. The overall multiplicity fraction is also consistent with being constant in age and across YMGs, which suggests that multiplicity rates for this mass range are largely set by 10Myr without appreciable evolution thereafter.
- ID:
- ivo://CDS.VizieR/J/A+A/576/A126
- Title:
- The 2009 multiwavelength campaign on Mrk421
- Short Name:
- J/A+A/576/A126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We perform an extensive characterization of the broadband emission of Mrk 421, as well as its temporal evolution, during the non-flaring (low) state. The high brightness and nearby location (z=0.031) of Mrk 421 make it an excellent laboratory to study blazar emission. The goal is to learn about the physical processes responsible for the typical emission of Mrk 421, which might also be extended to other blazars that are located farther away and hence are more difficult to study. We performed a 4.5-month multi-instrument campaign on Mrk 421 between January 2009 and June 2009, which included VLBA, F- GAMMA, GASP-WEBT, Swift, RXTE, Fermi-LAT, MAGIC, and Whipple, among other instruments and collaborations. This extensive radio to very-high-energy (VHE; E>100GeV) gamma-ray dataset provides excellent temporal and energy coverage, which allows detailed studies of the evolution of the broadband spectral energy distribution.
- ID:
- ivo://CDS.VizieR/J/A+A/588/A141
- Title:
- The MWA view of Fermi blazars
- Short Name:
- J/A+A/588/A141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Low-frequency radio arrays are opening a new window for the study of the sky, both to study new phenomena and to better characterize known source classes. Being flat-spectrum sources, blazars are so far poorly studied at low radio frequencies. We characterize the spectral properties of the blazar population at low radio frequency, compare the radio and high-energy properties of the gamma-ray blazar population, and search for radio counterparts of unidentified gamma-ray sources. We cross-correlated the 6100-deg^2^ Murchison Widefield Array Commissioning Survey catalogue with the Roma blazar catalogue, the third catalogue of active galactic nuclei detected by Fermi-LAT, and the unidentified members of the entire third catalogue of gamma-ray sources detected by Fermi-LAT. When available, we also added high-frequency radio data from the Australia Telescope 20GHz catalogue.
- 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.