- ID:
- ivo://CDS.VizieR/J/ApJS/81/5
- Title:
- Green Bank neutral hydrogen survey
- Short Name:
- J/ApJS/81/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Neutral hydrogen observations at 21cm, made at the Green Bank 91m telescope in 1984, 1985 and 1986, of a large sample of dwarf and other low surface brightness galaxies are presented. The majority of galaxies classified in the Uppsala General Catalogue as dwarf, irregular, Sdm, or later and with declinations north of the range of the Arecibo telescope ({delta}>38{deg}) have been observed, along with a number of galaxies farther south for flux comparisons with Arecibo observations (Schneider et al., 1990ApJS...72..245S, Paper I), totaling over 600 galaxies. About half of these galaxies have no previously published detections. In total, counting previous detections, over 80% of these late-type systems are detected at Green Bank. We have examined the galaxies for potential confusion with nearby galaxies, and we also present substantially better signal-to-noise measurements for many previously detected galaxies. Some general results of the Green Bank survey are discussed here, but the total data base of northern dwarf and low surface brightness galaxies, including new measurements of the galaxies' photographic magnitudes, will be examined in subsequent papers.
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- ID:
- ivo://nasa.heasarc/gbt31ghz
- Title:
- Green Bank Telescope 100-m 31-GHZ Radio Source Catalog
- Short Name:
- GBT31GHZ
- Date:
- 27 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The 100m Robert C. Byrd Green Bank Telescope (GBT) and the 40m Owens Valley Radio Observatory (OVRO) telescope have been used to conduct a 31-GHz survey of 3165 known extragalactic radio sources over 143 deg<sup>2</sup> of the sky. Target sources were selected from the NRAO VLA Sky Survey (NVSS) in fields observed by the Cosmic Background Imager (CBI); most are extragalactic active galactic nuclei (AGNs) with 1.4-GHz flux densities of 3-10 mJy. Using a maximum-likelihood analysis to obtain an unbiased estimate of the distribution of the 1.4 - 31 GHz spectral indices of these sources, the authors find a mean 31 - 1.4 GHz flux ratio of 0.110 +/- 0.003 corresponding to a spectral index alpha = -0.71+/-0.01 (S<sub>nu</sub> ~ nu<sup>alpha</sup>); 9.0% +/- 0.8% of the sources have alpha > -0.5 and 1.2% +/- 0.2% have alpha > 0. By combining this spectral-index distribution with 1.4GHz source counts, the authors predict 31-GHz source counts in the range 1 mJy <S<sub>31</sub> < 4 mJy, N(>S<sub>31</sub>) = (16.7+/-1.7)deg<sup>-2</sup>(S<sub>31</sub>/1mJy)<sup>(-0.80+/-0.07)</sup>. In this study, the authors present a detailed characterization of the impact of the discrete source foreground on arcminute-scale 31-GHz anisotropy measurements based upon two observational campaigns. The first campaign (the results of which are given in the OVRO31GHZ table) was carried out with the OVRO 40m telescope at 31 GHz from 2000 September through 2002 December. The second campaign (the results of which are given in the present table) used the GBT from 2006 February to May. A companion paper (Sievers et al. 2009arXiv0901.4540S) presents the five-year CBI total intensity power spectrum incorporating the results of the point-source measurements discussed here. Reported error bars include a 10% and 5% rms gain uncertainty for GBT and OVRO measurements, respectively. Sources detected at greater than 4 sigma at 31 GHz are flagged (detection_flag = 'Y'); for this calculation, the random gain uncertainty was excluded. In all 3165 sources were observed. The GBT catalog (this table) contains 1490 sources. Of the 2315 useful OVRO observations many of the non-detections (and a few detections) were superceded by more sensitive GBT observations; the OVRO catalog contained in the HEASARC's OVRO31GHZ table therefore contains data on 1675 sources. The detection rate of the OVRO measurements was 11%, and that of the GBT measurements 25%. In all, 18% of the sources were detected at 31 GHz. This table was created by the HEASARC in June 2012 based on CDS Catalpog J/ApJ/704/1433 file table3.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/A+A/569/A68
- Title:
- Green Bank Telescope observations of NGC 2403
- Short Name:
- J/A+A/569/A68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observed HI accretion around nearby galaxies can only account for a fraction of the gas supply needed to sustain the currently observed star formation rates. It is possible that additional accretion happens in the form of low column density cold flows, as predicted by numerical simulations of galaxy formation. To contrain the presence and properties of such flows, we present deep HI observations obtained with the NRAO Green Bank Telescope of an area measuring 4 by 4 degrees around NGC 2403. These observations, with a 5{sigma} detection limit of 2.4x10^18^cm^-2^ over a 20km/s linewidth, reveal the presence of a low-column density, extended cloud outside the main HI disk, about 17' (~16kpc or ~2R_25_) to the NW of the center of the galaxy. The total HI mass of the cloud is 6.3x10^6^M_{sun}_, or 0.15% of the total HI mass of NGC 2403. The cloud is associated with an 8kpc anomalous-velocity HI filament in the inner disk, previously observed in deep VLA observations by Fraternali et al. (2001ApJ...562L..47F, 2002AJ....123.3124F). We discuss several scenarios for the origin of the cloud, and conclude that it is either accreting from the intergalactic medium, or is the result of a minor interaction with a neigbouring dwarf galaxy.
- ID:
- ivo://nasa.heasarc/snrgreen
- Title:
- Green Catalog of Galactic SNRs (June 2017 Version)
- Short Name:
- SNR(Green)
- Date:
- 27 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This catalog of known Galactic supernova remnants (SNRs) is an updated version of the catalogs of Galactic SNRs presented in detail in Green (1984, 1988), in summary form in Green (1991, 1996, 2004, 2009), and on the Web (versions of 1995-July, 1996-August, 1998-September, 2000-August, 2001-December, 2004-January, 2006-April, 2009-March, and 2014-May). [Note that the version published in Green (1996) was produced in 1993.] This June 2017 version of the catalog contains 295 SNRs, and is based on results published in the literature up to the end of 2016. The basic summary data included in this catalog for each SNR are its designation, position, angular size (in arcminutes), type, flux density at 1 GHz, spectral index, and any other names by which it is known. Notes on these parameters, on possible remnants not included, and on questionable SNRs that are listed in this catalog, are given in the full version of the catalog on the Web at <a href="http://www.mrao.cam.ac.uk/surveys/snrs/snrs.info.html">http://www.mrao.cam.ac.uk/surveys/snrs/snrs.info.html</a> It should be noted that there are serious selection effects which apply to the identification of Galactic SNRs (e.g., Green 1991, 2004, 2005, 2009, 2014), so that care should be taken if these data are used in any statistical studies. This version of the Green Catalog of Galactic Supernova Remnants was ingested at the HEASARC in July 2017. It is based on the Catalogue of Galactic Supernova Remnants, 2017 June version, <a href="https://cdsarc.cds.unistra.fr/ftp/cats/VII/278">CDS Catalog VII/278</a>, file snrs.dat, obtained from the CDS at <a href="http://cdsarc.u-strasbg.fr/ftp/cats/VII/278/">http://cdsarc.u-strasbg.fr/ftp/cats/VII/278/</a>. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/A+A/623/A141
- Title:
- G345.5+1.5 region multiwavelength study
- Short Name:
- J/A+A/623/A141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The star formation process requires the dust and gas present in the Milky Way to self-assemble into dense reservoirs of neutral material where the new generation of stars will emerge. Star-forming regions are usually studied in the context of Galactic surveys, but dedicated observations are sometimes needed when the study reaches beyond the survey area. A better understanding of the star formation process in the Galaxy can be obtained by studying several regions. This allows increasing the sample of objects (clumps, cores, and stars) for further statistical works and deeper follow-up studies. Here, we studied the G345.5+1.5 region, which is located slightly above the Galactic plane, to understand its star formation properties. We combined Large Apex BOlometer CAmera (LABOCA) and ^12^CO(4-3) transition line (NANTEN2) observations complemented with the Hi-GAL and Spitzer-GLIMPSE surveys to study the star formation toward this region. We used the Clumpfind algorithm to extract the clumps from the 870um and ^12^CO(4-3) data. Radio emission at 36cm was used to estimate the number of HII regions and to remove the contamination from the free-free emission at 870um. We employed color-color diagrams and spectral energy distribution (SED) slopes to distinguish between prestellar and protostellar clumps.We studied the boundedness of the clumps through the virial parameter. Finally, we estimated the star formation efficiency (SFE) and star formation rate (SFR) of the region and used the Schmidt-Kennicutt diagram to compare its ability to form stars with other regions of the Galactic plane. Of the 13 radio sources that we found using the MGPS-2 catalog, 7 are found to be associated with Hii regions corresponding to late-B or early-O stars. We found 45 870um clumps with diameters between 0.4 and 1.2pc and masses between 43M_{sun}_ and 3923M_{sun}_, and 107 ^12^CO clumps with diameters between 0.4 pc and 1.3pc and masses between 28M_{sun}_ and 9433M_{sun}_. More than 50% of the clumps are protostellar and bounded and are able to host (massive) star formation. High SFR and SFR density (S FR) values are associated with the region, with an SFE of a few percent. With submillimeter, CO transition, and short-wavelength infrared observations, our study reveals a population of massive stars, protostellar and bound starless clumps, toward G345.5+1.5. This region is therefore actively forming stars, and its location in the starburst quadrant of the Schmidt-Kennicutt diagram is comparable to other star-forming regions found within the Galactic plane.
- ID:
- ivo://CDS.VizieR/J/A+A/536/A89
- Title:
- g'r'i' and redshift of Abell 2254 galaxies
- Short Name:
- J/A+A/536/A89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The mechanisms giving rise to diffuse radio emission in galaxy clusters and, in particular, their connection with cluster mergers are still being debated. We explore the internal dynamics of Abell 2254, which has been shown to host a very clumpy and irregular radio halo. Our analysis is mainly based on redshift data for 128 galaxies acquired at the Telescopio Nazionale Galileo. We combined galaxy velocities and positions to select 110 cluster galaxies and analyze its internal dynamics. We also used new (g', r', i') photometric data acquired at the Isaac Newton Telescope, and (V, i') photometric data available in the Subaru Archive. X-ray data from the XMM-Newton Science Archive were analyzed to study the hot gas component.
7617. griBVI photometry in M37
- ID:
- ivo://CDS.VizieR/J/ApJ/691/342
- Title:
- griBVI photometry in M37
- Short Name:
- J/ApJ/691/342
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the course of conducting a deep (14.5<~r<~23), 20 night survey for transiting planets in the rich ~550Myr old open cluster M37, we have measured the rotation periods of 575 stars, which lie near the cluster main sequence, with masses 0.2M_{sun}_<~M<~1.3M_{sun}_. This is the largest sample of rotation periods for a cluster older than 500Myr. Using this rich sample we investigate a number of relations between rotation period, color, and the amplitude of photometric variability.
- ID:
- ivo://CDS.VizieR/J/ApJ/801/67
- Title:
- Grid of binary colors in M30 (NGC7099)
- Short Name:
- J/ApJ/801/67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Two separated sequences of blue straggler stars (BSSs) have been revealed by Ferraro et al. (2009Natur.462.1028F) in the color-magnitude diagram (CMD) of the Milky Way globular cluster M30. Their presence has been suggested to be related to the two BSS formation channels (namely, collisions and mass transfer in close binaries) operating within the same stellar system. The blue sequence was indeed found to be well reproduced by collisional BSS models. In contrast, no specific models for mass-transfer BSSs were available for an old stellar system like M30. Here we present binary evolution models, including case-B mass transfer and binary merging, specifically calculated for this cluster. We discuss in detail the evolutionary track of a 0.9+0.5M_{sun}_ binary, which spends approximately 4Gyr in the BSS region of the CMD of a 13Gyr old cluster. We also run Monte Carlo simulations to study the distribution of mass-transfer BSSs in the CMD and to compare it with the observational data. Our results show that (1) the color and magnitude distribution of synthetic mass-transfer BSSs defines a strip in the CMD that nicely matches the observed red-BSS sequence, thus providing strong support to the mass-transfer origin for these stars; (2) the CMD distribution of synthetic BSSs never attains the observed location of the blue-BSS sequence, thus reinforcing the hypothesis that the latter formed through a different channel (likely collisions); (3) most (~60%) of the synthetic BSSs are produced by mass-transfer models, while the remaining <40% requires the contribution from merger models.
- ID:
- ivo://CDS.VizieR/J/MNRAS/358/521
- Title:
- Grid of chemical evolution models for galaxies
- Short Name:
- J/MNRAS/358/521
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a generalization of the multiphase chemical evolution model applied to a wide set of theoretical galaxies with different masses and evolutionary rates. This generalized set of models has been computed using the so-called Universal Rotation Curve from Persic et al. (1996MNRAS.281...27P) to calculate the radial mass distribution of 44 theoretical protogalaxies. This distribution is a fundamental input which, besides its own effect on the galaxy evolution, defines the characteristic collapse time-scale or gas infall rate onto the disc. We have adopted 10 sets of values, between 0 and 1, for the molecular cloud and star formation efficiencies, as corresponding to their probability nature, for each one of the radial distributions of total mass. Thus, we have constructed a bi-parametric grid of models, depending on those efficiency sets and on the rotation velocity, whose results are valid in principle for any spiral or irregular galaxy. The model results provide the time evolution of different regions of the disc and the halo along galactocentric distance, measured by the gas (atomic and molecular) and stellar masses, the star formation rate and chemical abundances of 14 elements, for a total of 440 models. This grid may be used to estimate the evolution of a given galaxy for which only present time information, such as radial distributions of elemental abundances, gas densities and/or star formation, which are the usual observational constraints of chemical evolution models, is available.
- ID:
- ivo://CDS.VizieR/J/A+A/455/247
- Title:
- Grid of close binaries experiencing mass exchange
- Short Name:
- J/A+A/455/247
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To simulate the population of the primordial blue stragglers in old open clusters, a grid of close binaries experiencing mass exchange is needed. To this aim, various combinations that can trigger mass exchange for the donor masses of 0.1M_{sun}_ to 2.0M_{sun}_ are calculated with a fine grid in parameters. The mass range of the accretor is from 0.1M_{sun}_ to the mass of the corresponding donor. The mass intervals of the donors and the accretors are all 0.1M_{sun}_. To cover all possible cases of close binaries, the orbit separation ranges from 1.0 to 50.0R_{sun}_ with a grid interval of 1.0R_{sun}_. Following the numerical scheme described above, a grid for six ages from 1.0Gyr to 6.0Gyr is obtained. In this table, mass, effective temperature, luminosity, gravity, Hydrogen abundance in the core, Helium abundance in the core, B magnitude, V magnitude, B-V color, mass ratio, orbital separation and period of the close binaries experiencing mass exchange are given.