- ID:
- ivo://CDS.VizieR/J/AJ/161/191
- Title:
- H{alpha} photometry in NGC 7020
- Short Name:
- J/AJ/161/191
- Date:
- 20 Jan 2022
- Publisher:
- CDS
- Description:
- The galaxy NGC7020 displays an exotic hexagonal ringlike central structure with conspicuous ansae located at two opposite vertices and a tenuous external ring populated by H ii regions. Inside and around the hexagonal structure, H{alpha} emission is also present at the inner disk. To characterize the population of the HII regions, as well as their ionizing clusters, we imaged NGC7020 with narrowband H{alpha} and nearby continuum filters attached to GMOS-S installed on the Gemini South telescope. We found 202 HII regions or complexes of HII regions evenly distributed between the outer ring and the central disk The nucleus and ansae also present H{alpha} emission. The equivalent width of the H{alpha} line (WH{alpha}) is systematically greater at the regions of the outer ring relative to those of the inner disk. We discuss the influence of the metallicity gradient of the disk and the upper limit of the masses of the initial mass function on WH{alpha}, and we conclude that the data are still consistent with the occurrence of a younger burst of HII region formation in the outer ring. The central regions present more massive clusters, M>~106M{sun}, than those of the outer ring (M<~106M{sun}). Three clusters within 5" of the nucleus present masses higher than 108M{sun}. The presence of diffuse H{alpha} emission in the inner 5" suggests gas flows in the nuclear region.
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- ID:
- ivo://CDS.VizieR/J/ApJS/166/505
- Title:
- H{alpha} photometry of face-on galaxies
- Short Name:
- J/ApJS/166/505
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a survey of the photometric and kinematic properties of 39 nearby, nearly face-on disk galaxies. Our approach exploits echelle-resolution integral-field spectroscopy of the H{alpha} regions, obtained with DensePak on the WIYN 3.5m telescope Bench Spectrograph. These data are complemented by HI line profiles observed with the Nancay radio telescope for 25 of these sample galaxies. Twelve additional line widths are available for sample galaxies from the literature. In this paper, we introduce the goals of this survey, define the sample selection algorithm, and amass the integral field spectroscopic data and HI line widths. We establish spatially integrated H{alpha} line widths for the sample. We test the veracity of these spatially integrated line profiles by convolving narrowband imaging data with velocity field information for one of the sample galaxies, PGC 38268, and also by comparing to HI line profiles.
- ID:
- ivo://CDS.VizieR/J/ApJ/704/1657
- Title:
- H{alpha} rotation curves for 10 spiral galaxies
- Short Name:
- J/ApJ/704/1657
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- H{alpha} rotation curves for a sample of 10 late-type spiral galaxies. All rotation curves were derived using Harmonic decomposition method applied to Fabry-Perot velocity fields. We have used the rotation curves combined with pattern speeds from the Tremaine-Weinberg method, to study the dynamics of bars and spiral arms in late-type spiral galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/465/4180
- Title:
- H{alpha} stars in M31 HST photometry
- Short Name:
- J/MNRAS/465/4180
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sample of 224 stars that emit H{alpha} (H{alpha} stars) in the Andromeda galaxy (M31). The stars were selected from ~5000 spectra, collected as part of the Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo survey using Keck II/DEIMOS. We used six-filter Hubble Space Telescope photometry from the Panchromatic Hubble Andromeda Treasury survey to classify and investigate the properties of the H{alpha} stars. We identified five distinct categories of H{alpha} star: B-type main-sequence (MS) stars, 'transitioning'-MS (T-MS) stars, red core He burning (RHeB) stars, non-C-rich asymptotic giant branch (AGB) stars, and C-rich AGB stars. We found that ~12 per cent of B-type stars exhibit H{alpha} emission (Be stars). The frequency of Be to all B stars is known to vary with the metallicity of their environment. Comparing this proportion of Be stars with other environments around the Local Group, the result could indicate that M31 is more metal-rich than the Milky Way. We predict that the 17 T-MS H{alpha} stars are Be stars evolving off the MS with fading H{alpha} emission. We separated RHeB from AGB H{alpha} stars. We conclude that the 61 RHeB and AGB stars are likely to be long-period variables. We found that ~14 per cent of C-rich AGB stars (C stars) emit H{alpha}, which is an upper limit for the ratio of C-rich Miras to C stars. This catalogue of H{alpha} stars will be useful to constrain stellar evolutionary models, calibrate distance indicators for intermediate-age populations, and investigate the properties of M31.
- ID:
- ivo://CDS.VizieR/J/A+A/446/839
- Title:
- H{alpha} surface photometry in nearby clusters
- Short Name:
- J/A+A/446/839
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the H{alpha} imaging observations of 273 late-type galaxies in the nearby rich galaxy clusters Virgo, A 1367, Coma, Cancer, Hercules and in the Great Wall, carried out primarily with the 2.1m telescope of the San Pedro Martir Observatory (SPM) and with the ESO/3.6m telescope. We derived the H{alpha}+[NII] fluxes and equivalent widths. The H{alpha} survey reached completion for an optically selected sample of nearby galaxies in and outside rich clusters. Taking advantage of the completeness of the data set, the dependence of H{alpha} properties on the Hubble type was determined for late-type galaxies in the Virgo cluster. Differences in the gaseous content partly account for the large scatter of the H{alpha} EW within each Hubble-type class. We studied the radial distributions of the H{alpha} EW around Coma+A 1367 and the Virgo clusters in two luminosity bins. Luminous galaxies show a decrease in their average H{alpha} EW in the inner ~1 virial radius, while low-luminosity galaxies do not show this trend. Description:
- ID:
- ivo://CDS.VizieR/J/A+A/396/449
- Title:
- H{alpha} surface photometry in Virgo
- Short Name:
- J/A+A/396/449
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- H{alpha}+[NII] imaging observations of 369 late-type (spiral) galaxies in the Virgo cluster and in the Coma/A1367 supercluster are analyzed, covering 3 rich nearby clusters (A1367, Coma and Virgo) and nearly isolated galaxies in the Great-Wall. They constitute an optically selected sample (mp<16.0) observed with ~60% completeness. These observations provide us with the current (T<10^7^yrs) star formation properties of galaxies that we study as a function of the clustercentric projected distances (Theta). The expected decrease of the star formation rate (SFR), as traced by the H{alpha} equivalent width, with decreasing Theta is found only when galaxies brighter than Mp~19.5 are considered. Fainter objects show no or reverse trends. We also include in our analysis Near Infrared data, providing information on the old (T>10^9^yrs) stars. Put together, the young and the old stellar indicators give the ratio of currently formed stars over the stars formed in the past, or "birthrate" parameter b. For the considered galaxies we also determine the "global gas content" combining HI with CO observations. We define the "gas deficiency'' parameter as the logarithmic difference between the gas content of isolated galaxies of a given Hubble type and the measured gas content.
- ID:
- ivo://CDS.VizieR/J/ApJ/862/25
- Title:
- H{alpha} & UV emission scale heights for edge-on gal.
- Short Name:
- J/ApJ/862/25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compare vertical profiles of the extraplanar H{alpha} emission to those of the UV emission for 38 nearby edge-on late-type galaxies. It is found that detection of the "diffuse" extraplanar dust (eDust), traced by the vertically extended, scattered UV starlight, always coincides with the presence of the extraplanar H{alpha} emission. A strong correlation between the scale heights of the extraplanar H{alpha} and UV emissions is also found; the scale height at H{alpha} is found to be ~0.74 of the scale height at FUV. Our results may indicate the multiphase nature of the diffuse ionized gas and dust in the galactic halos. The existence of eDust in galaxies where the extraplanar H{alpha} emission is detected suggests that a larger portion of the extraplanar H{alpha} emission than that predicted in previous studies may be caused by H{alpha} photons that originate from HII regions in the galactic plane and are subsequently scattered by the eDust. This possibility raise an advantage in studying the extraplanar diffuse ionized gas. We also find that the scale heights of the extraplanar emissions normalized to the galaxy size correlate well with the star formation rate surface density of the galaxies. The properties of eDust in our galaxies is on a continuation line of that found through previous observations of the extraplanar polycyclic aromatic hydrocarbons emission in more active galaxies known to have galactic winds.
- ID:
- ivo://CDS.VizieR/J/A+A/358/77
- Title:
- Hamburg/ESO survey for bright QSOs. III.
- Short Name:
- J/A+A/358/77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Appendix to the above paper, containing the two large tables A.1 and B.1 described in the paper. Table A.1 gives the basic properties of the 207 survey fields used to construct the flux-limited sample, including field-dependent magnitude limits and adopted extinction values. Table B.1 lists the 415 QSOs and Seyfert 1 galaxies that form the sample, with positions, redshift and magnitudes, plus a cross-identification with the 1995 version of the AGN catalogue by Veron-Cetty & Veron (see Cat. <VII/215>).
- ID:
- ivo://CDS.VizieR/J/A+A/406/535
- Title:
- Hamburg/RASS Cat. of optical ident. V3.0
- Short Name:
- J/A+A/406/535
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Hamburg/RASS Catalogue (HRC) of optical identifications of X-ray sources at high-galactic latitude. The HRC includes all X-ray sources from the ROSAT Bright Source Catalogue (RASS-BSC) with galactic latitude |b|>=30{deg} and declination DE>=0{deg}. In this part of the sky covering ~10 000 deg^2^ the RASS-BSC contains 5341 X-ray sources. For the optical identification we used blue Schmidt prism and direct plates taken for the northern hemisphere Hamburg Quasar Survey (HQS) which are now available in digitized form. The limiting magnitudes are 18.5 and 20, respectively. For 82% of the selected RASS-BSC an identification could be given. For the rest either no counterpart was visible in the error circle or a plausible identification was not possible. With ~42% AGN represent the largest group of X-ray emitters, ~31% have a stellar counterpart, whereas galaxies and cluster of galaxies comprise only ~4% and ~5%, respectively. In ~3% of the RASS-BSC sources no object was visible on our blue direct plates within 40" around the X-ray source position. The catalogue is used as a source for the selection of (nearly) complete samples of the various classes of X-ray emitters.
- ID:
- ivo://CDS.VizieR/J/A+AS/137/299
- Title:
- Hamburg/SAO Survey for ELGs. II.
- Short Name:
- J/A+AS/137/299
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the second part of the Hamburg/SAO Survey for Emission-Line Galaxies (HSS therein, SAO - Special Astrophysical Observatory, Russia) which is based on the digitized objective-prism photoplates database of the Hamburg Quasar Survey (HQS). The main goal of the project is the search for emission-line galaxies (ELG) in order to create a new deep sample of blue compact/HII galaxies (BCG) in a large sky area. Another important goal of this work is to search for new extremely low-metallicity galaxies. In this paper we present new results of spectroscopy obtained with the 6m Russian telescope. The main ELG candidate selection criteria applied are blue or flat enough continuum (near 4000A) and the presence of strong or moderate emission lines close to 5000A recognized on digitized prism spectra of galaxies with the survey estimated B-magnitudes in the range 16 - 19.5. No other criteria were applied. The spectroscopy resulted in detection and quantitative spectral classification of 134 emission-line objects. For 121 of them the redshifts are determined for the first time. For 13 ELGs known before emission line ratios are presented at first time. 108 of 134 emission-line objects are classified as BCG/HII galaxies and 6 probable BCGs, 6 as QSOs, 1 as Seyfert galaxy, 1 as super-association in a dwarf spiral galaxy, 2 as probable LINERs, 14 are low excitation objects - either of starburst nuclei (SBN), or dwarf amorphous nuclei starburst galaxy (DANS) type -, and 1 nonclassified. 23 galaxies did not show significant emission lines. The five most metal-deficient BCGs discovered have oxygen abundances log(O/H)+12 in the range 7.4 to 7.7, similar to the most metal-deficient BCGs known before.
