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621. Hamburg/SAO Survey for ELGs. II.
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.
622. Hamburg/SAO Survey for ELGs. III.
ID:
ivo://CDS.VizieR/J/A+AS/142/417
Title:
Hamburg/SAO Survey for ELGs. III.
Short Name:
J/A+AS/142/417
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the third list with results of the Hamburg/SAO Survey for Emission-Line Galaxies (HSS therein, SAO - Special Astrophysical Observatory, Russia). This survey is based on the digitized objective-prism photoplate database of the Hamburg Quasar Survey (HQS). Here, we present new spectroscopic results of candidates which were obtained in 1998 with the 2.1m KPNO and the 2.2m Calar Alto telescopes. All candidates are selected in the declination band +35{deg} to +40{deg}. The follow-up spectroscopy with the 2m class telescopes confirmed 85 emission-line objects out of 113 observed candidates and allowed their quantitative spectral classification. For 80 of them, the redshifts are determined for the first time. For 5 previously known Emission-Line Galaxies (ELGs), line ratios are presented for the first time. We could classify 55 out of the 85 emission-line objects as BCG/HII galaxies or probable BCGs (Blue Compact Galaxies) , 4 - as QSOs, 6 - as Seyfert galaxies, 1 - as super-association in a subluminous spiral galaxy, and 11 are low-excitation objects - either starburst nuclei (SBN), or dwarf amorphous nuclei starburst galaxies (DANS). We could not classify 8 ELGs. Further, for 8 more galaxies we did not detect any significant emission lines.
623. Hamburg/SAO Survey for ELGs. VI.
ID:
ivo://CDS.VizieR/J/A+A/442/109
Title:
Hamburg/SAO Survey for ELGs. VI.
Short Name:
J/A+A/442/109
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the sixth list with results of the Hamburg/SAO Survey for Emission-Line Galaxies. The final list resulted from follow-up spectroscopy conducted with the 4.5m MMT telescope in 1996, and with 2.2m CAHA and 6m SAO telescopes in 2000 to 2003. The data of this snap-shot spectroscopy survey confirmed 134 emission-line objects out of 182 observed candidates and allowed their quantitative spectral classification and redshift determination. We classify 73 emission-line objects as definite or probable blue compact or HII galaxies (BCG), 8 as QSOs, 4 as Seyfert 1 and 2 galaxies. 30 low-excitation objects were classified as definite or probable starburst nuclei (SBN), 3 as dwarf amorphous nuclei starburst galaxies (DANS) and 2 as LINERs. Due to the low signal-to-noise ratio we could not classify 14 ELGs (NON). For another 9 galaxies we did not detect any significant emission lines. For 98 emission-line galaxies, the redshifts and/or line intensities are determined for the first time. For the remaining 28 previously-known ELGs we give either improved data the line intensities or some independent measurements. The detection rate of ELGs is ~70%. This paper completes the classification of strong-lined ELGs found in the zone of the Hamburg/SAO survey. Together with previously known BCG/HII galaxies in this zone, this sample of ~500 objects is the largest to date in a well bound region.
624. HAQ survey: red QSO candidates follow-up
ID:
ivo://CDS.VizieR/J/ApJS/217/5
Title:
HAQ survey: red QSO candidates follow-up
Short Name:
J/ApJS/217/5
Date:
21 Oct 2021
Publisher:
CDS
Description:
Quasi-stellar objects (QSOs) whose spectral energy distributions (SEDs) are reddened by dust either in their host galaxies or in intervening absorber galaxies are to a large degree missed by optical color selection criteria like the ones used by the Sloan Digital Sky Survey (SDSS). To overcome this bias against red QSOs, we employ a combined optical and near-infrared (near-IR) color selection. In this paper, we present a spectroscopic follow-up campaign of a sample of red candidate QSOs which were selected from the SDSS and the UKIRT Infrared Deep Sky Survey (UKIDSS). The spectroscopic data and SDSS/UKIDSS photometry are supplemented by mid-infrared photometry from the Wide-field Infrared Survey Explorer. In our sample of 159 candidates, 154 (97%) are confirmed to be QSOs. We use a statistical algorithm to identify sightlines with plausible intervening absorption systems and identify nine such cases assuming dust in the absorber similar to Large Magellanic Cloud sightlines. We find absorption systems toward 30 QSOs, 2 of which are consistent with the best-fit absorber redshift from the statistical modeling. Furthermore, we observe a broad range in SED properties of the QSOs as probed by the rest-frame 2{mu}m flux. We find QSOs with a strong excess as well as QSOs with a large deficit at rest-frame 2{mu}m relative to a QSO template. Potential solutions to these discrepancies are discussed. Overall, our study demonstrates the high efficiency of the optical/near-IR selection of red QSOs.
625. HARPS and X-shooter spectra of Southern M dwarfs
ID:
ivo://CDS.VizieR/J/ApJ/878/134
Title:
HARPS and X-shooter spectra of Southern M dwarfs
Short Name:
J/ApJ/878/134
Date:
25 Oct 2021 00:49:19
Publisher:
CDS
Description:
We present the homogeneous analysis of a sample of Southern early-type M dwarfs in the solar neighborhood (d<60pc). We used the MCAL technique to derive the effective temperature Teff, metallicity [Fe/H], and activity index i_a_(H_alpha_) of 420 M stars using HARPS spectra. The effective temperature Teff, surface gravity logg, metallicity [Fe/H], and projected rotational velocity V_rot_sini of 153 M0-M6 dwarfs were determined by fitting the observed intermediate-resolution spectra from the VIS arm of VLT/X-shooter with a grid of BT-Settl stellar atmosphere models. We estimated the typical uncertainties of the fit with X-shooter spectra by varying region-to-region results by {sigma}T_eff_~50K, {sigma}logg~0.2, and {sigma}[Fe/H]~0.2dex. Photometric verification of Teff for the 295 stars from the HARPS sample and the 61 stars from the X-shooter sample is also provided. We compared our results from different methods to estimate absolute uncertainty in determining the physical properties of M dwarfs.
626. HARPS M dwarf sample magnetic activity
ID:
ivo://CDS.VizieR/J/A+A/600/A13
Title:
HARPS M dwarf sample magnetic activity
Short Name:
J/A+A/600/A13
Date:
21 Oct 2021
Publisher:
CDS
Description:
Atmospheric magnetic fields in stars with convective envelopes heat stellar chromospheres, and thus increase the observed flux in the CaII H and K doublet. Starting with the historical Mount Wilson monitoring program, these two spectral lines have been widely used to trace stellar magnetic activity, and as a proxy for rotation period (Prot) and consequently for stellar age. Monitoring stellar activity has also become essential in filtering out false-positives due to magnetic activity in extra-solar planet surveys. The CaII emission is traditionally quantified through the R'_HK_-index, which compares the chromospheric flux in the doublet to the overall bolometric flux of the star. Much work has been done to characterize this index for FGK-dwarfs, but M dwarfs - the most numerous stars of the Galaxy - were left out of these analyses and no calibration of their CaII H and K emission to an R'_HK_ exists to date. We set out to characterize the magnetic activity of the low- and very-low-mass stars by providing a calibration of the R'_HK_-index that extends to the realm of M dwarfs, and by evaluating the relationship between R'_HK_ and the rotation period.. We calibrated the bolometric and photospheric factors for M dwarfs to properly transform the S-index (which compares the flux in the CaII H and K lines to a close spectral continuum) into the R'_HK_. We monitored magnetic activity through the CaII H and K emission lines in the HARPS M dwarf sample.
627. HARPS observations of eight galactic Cepheids
ID:
ivo://CDS.VizieR/J/A+A/489/1255
Title:
HARPS observations of eight galactic Cepheids
Short Name:
J/A+A/489/1255
Date:
21 Oct 2021
Publisher:
CDS
Description:
We show that residual {gamma}-velocities (compared to a axisymmetric rotation model of the milky Way) are an intrinsic property of Cepheids. We observed eight galactic Cepheids with the HARPS spectroscope, focusing specifically on 17 spectral lines. For each spectral line of each star, we computed the {gamma}-velocity (resp. {gamma}-asymmetry) as an average value of the interpolated radial velocity (resp. line asymmetry) curve. For each Cepheid in our sample, a linear relation is found between the {gamma}-velocities of the various spectral lines and their corresponding {gamma}-asymmetries, showing that residual {gamma}-velocities stem from the intrinsic properties of Cepheids. We also provide a physical reference to the stellar {gamma}-velocity: it should be zero when the {gamma}-asymmetry is zero. Following this definition, we provide very precise and physically calibrated estimates of the {gamma}-velocities for all stars of our sample.
628. HARPS observations of nine galactic Cepheids
ID:
ivo://CDS.VizieR/J/A+A/453/309
Title:
HARPS observations of nine galactic Cepheids
Short Name:
J/A+A/453/309
Date:
21 Oct 2021
Publisher:
CDS
Description:
The ratio of pulsation to radial velocity (the projection factor) is currently limiting the accuracy of the Baade-Wesselink method, and in particular of its interferometric version recently applied to several nearby Cepheids. This work aims at establishing a link between the line asymmetry evolution over the Cepheids' pulsation cycles and their projection factor, with the final objective to improve the accuracy of the Baade-Wesselink method for distance determinations. We present HARPS high spectral resolution observations (R=120000) of nine galactic Cepheids: R Tra, S Cru, Y Sgr, beta Dor, zeta Gem, Y Oph, RZ Vel, l Car and RS Pup, having a good period sampling (P=3.39d to P=41.52d). We fit spectral line profiles by an asymmetric bi-Gaussian to derive radial velocity, Full-Width at Half-Maximum in the line (FWHM) and line asymmetry for all stars.
629. HARPS observations of nine galactic Cepheids
ID:
ivo://CDS.VizieR/J/A+A/502/951
Title:
HARPS observations of nine galactic Cepheids
Short Name:
J/A+A/502/951
Date:
21 Oct 2021
Publisher:
CDS
Description:
We observed eight galactic Cepheids with the HARPS spectrograph. For each star, we derive an interpolated cross-correlated radial velocity curve using the HARPS pipeline. Pulsating phases and HARPS radial velocity measurements can be found in Table 1. The cross correlation method is widely used to derive the radial velocity curve of Cepheids when the signal to noise ratio of the spectra is low. However, if it is used with an inac curate projection factor, it might introduce some biases in the Baade-Wesselink (BW) methods of determining the distance of Cepheids. In addition, it might affect the average value of the radial velocity curve (or gamma-velocity) important for Galactic structure studies. See the paper for details and results.
630. HARPSpol magnetic massive stars
ID:
ivo://CDS.VizieR/J/A+A/567/A28
Title:
HARPSpol magnetic massive stars
Short Name:
J/A+A/567/A28
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Magnetism in Massive Stars (MiMeS) project aims at understanding the origin of the magnetic fields in massive stars as well as their impact on stellar internal structure, evolution, and circumstellar environment. One of the objectives of the MiMeS project is to provide stringent observational constraints on the magnetic fields of massive stars; however, identification of magnetic massive stars is challenging, as only a few percent of high-mass stars host strong fields detectable with the current instrumentation. Hence, one of the first objectives of the MiMeS project was to search for magnetic objects among a large sample of massive stars, and to build a sub-sample for in-depth follow-up studies required to test the models and theories of fossil field origins, magnetic wind confinement and magnetospheric properties, and magnetic star evolution. We obtained high-resolution spectropolarimetric observations of a large number of OB stars thanks to three large programs (LP) of observations that have been allocated on the high-resolution spectropolarimeters ESPaDOnS, Narval, and the polarimetric module HARPSpol of the HARPS spectrograph.