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931. H{alpha} flux of ACCG 114 galaxies
ID:
ivo://CDS.VizieR/J/ApJ/549/820
Title:
H{alpha} flux of ACCG 114 galaxies
Short Name:
J/ApJ/549/820
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a wide-field survey for H{alpha}-emitting galaxies in the cluster AC 114 at z=0.32. Spectra centered on H{alpha} at the cluster redshift have been obtained for 586 galaxies to I_tot_~22 out to a radius of ~h_50_^-1^Mpc. At most, only ~10% of these were found to be H{alpha}-emitting cluster members. These objects are predominantly blue and of late-type spiral morphology, consistent with them hosting star formation. However, ~65% of the cluster members classified morphologically as spirals (with HST) have no detectable H{alpha} emission; star formation and morphological evolution in cluster galaxies appear to be largely decoupled. Changes in the H{alpha} detection rate and the strength of H{alpha} emission with environment (as traced by local galaxy density) are found to be weak within the region studied. Star formation within the cluster members is also found to be strongly and uniformly suppressed with the rates inferred from the H{alpha} emission not exceeding 4M_{sun}_/yr, and AC 114's H{alpha} luminosity function being an order of magnitude below that observed for field galaxies at the same redshift. None of the galaxies detected have the high star formation rates associated with "starburst" galaxies; however, this may still be reconcilable with the known (8%+/-3%) fraction of "post-starburst" galaxies within AC 114, given the poorly determined but short lifetimes of starbursts and the possibility that much of the associated star formation is obscured by dust.
932. H{alpha} & H{beta} spectral regions of low-z QSOs
ID:
ivo://CDS.VizieR/J/ApJS/234/16
Title:
H{alpha} & H{beta} spectral regions of low-z QSOs
Short Name:
J/ApJS/234/16
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using the quasars with z_em_<0.9 from the Baryon Oscillation Spectroscopic Survey, we measure the spectral characteristics, including continuum and emission lines, around the H{beta} and H{alpha} spectral regions, which are lacking in Quasar Data Release 12 (DR12Q). We estimate the virial black hole mass from broad H{alpha} and/or H{beta}, and infer quasar redshifts from [OIII]{lambda}5007 emission lines. All the measurements and derived quantities are publicly available. A comparison between [OIII]{lambda}5007 redshifts and the visual inspection redshifts included in DR12Q indicates that the visual inspection redshifts are robust. We find that the full widths at half maximum of the broad H{alpha} are consistent with those of the broad H{beta}, while both the equivalent widths and line luminosities of the broad H{alpha} are obviously larger than the corresponding quantities of the broad H{beta}. We also find that there is an obviously systematic offset between the H{beta} and H{alpha} based mass if they are inferred from the empirical relationships in the literature. Using our large quasar sample, we have improved the H{beta} and H{alpha} based mass estimators by minimizing the difference between the H{beta}- and H{alpha}-based masses. For the black hole mass estimator (Equation (1)), we find that the coefficients (a,b)=(7.00,0.50) for H{alpha} and (a,b)=(6.96,0.50) for H{beta} are the best choices.
933. H{alpha} imaging of Herschel Reference Survey
ID:
ivo://CDS.VizieR/J/A+A/579/A102
Title:
H{alpha} imaging of Herschel Reference Survey
Short Name:
J/A+A/579/A102
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new H{alpha}+[NII] imaging data of late-type galaxies in the Herschel Reference Sample aimed at studying the star formation properties of a K-band-selected, volume-limited sample of nearby galaxies. The H{alpha}+[NII] data are corrected for [NII] contamination and dust attenuation using different recipes based on the Balmer decrement and the 24um luminosities. We show that the H{alpha} luminosities derived with different corrections give consistent results only whenever the the uncertainty on the estimate of the Balmer decrement is [C(H{beta})]<=0.1. We use these data to derive the star formation rate of the late-type galaxies of the sample, and compare these estimates to those determined using independent monochromatic tracers (FUV, radio continuum) or the output of spectral energy distribution (SED) fitting codes. This comparison suggests that the 24um based dust extinction correction for the H{alpha} data might be non universal, and that it should be used with caution in all objects with a low star formation activity, where dust heating can be dominated by the old stellar population. Furthermore, because of the sudden truncation of the star formation activity of cluster galaxies occurring after their interaction with the surrounding environment, the stationarity conditions required to transform monochromatic fluxes into star formation rates might not always be satisfied in tracers other than the H{alpha} luminosity. In a similar way, the parametrisation of the star formation history generally used in SED fitting codes might not be adequate for these recently interacting systems. We then use the derived star formation rates to study the SFR luminosity distribution and the typical scaling relations of the late-type galaxies of the HRS. We observe a systematic decrease of the specific star formation rate with increasing stellar mass, stellar mass surface density, and metallicity. We also observe an increase of the asymmetry and smoothness parameters measured in the H{alpha}-band with increasing SSFR, probably induced by an increase of the contribution of giant HII regions to the H{alpha} luminosity function in star-forming low-luminosity galaxies.
934. H{alpha} indices in M low-mass stars
ID:
ivo://CDS.VizieR/J/ApJ/764/3
Title:
H{alpha} indices in M low-mass stars
Short Name:
J/ApJ/764/3
Date:
21 Oct 2021
Publisher:
CDS
Description:
Through the McDonald Observatory M Dwarf Planet Search, we have acquired nearly 3000 high-resolution spectra of 93 late-type (K5-M5) stars over more than a decade using the High Resolution Spectrograph on the Hobby-Eberly Telescope. This sample provides a unique opportunity to investigate the occurrence of long-term stellar activity cycles for low-mass stars. In this paper, we examine the stellar activity of our targets as reflected in the H{alpha} feature. We have identified periodic signals for six stars, with periods ranging from days to more than 10 years, and find long-term trends for seven others. Stellar cycles with P>=1 year are present for at least 5% of our targets. Additionally, we present an analysis of the time-averaged activity levels of our sample, and search for correlations with other stellar properties. In particular, we find that more massive, earlier type (M0-M2) stars tend to be more active than later type dwarfs. Furthermore, high-metallicity stars tend to be more active at a given stellar mass. We also evaluate H{alpha} variability as a tracer of activity-induced radial velocity (RV) variation. For the M dwarf GJ 1170, H{alpha} variation reveals stellar activity patterns matching those seen in the RVs, mimicking the signal of a giant planet, and we find evidence that the previously identified stellar activity cycle of GJ 581 may be responsible for the recently retracted planet f in that system. In general, though, we find that H{alpha} is not frequently correlated with RV at the precision (typically 6-7m/s) of our measurements.
935. H{alpha}+[NII] observations of M81 HII regions
ID:
ivo://CDS.VizieR/J/AJ/126/1286
Title:
H{alpha}+[NII] observations of M81 HII regions
Short Name:
J/AJ/126/1286
Date:
21 Oct 2021
Publisher:
CDS
Description:
In a first of a series of studies of the H{alpha}+[NII] emission from nearby spiral galaxies, we present measurements of H{alpha}+[NII] emission from HII regions in M81. Our method uses large-field CCD images and long-slit spectra and is part of the ongoing Beijing-Arizona-Taipei-Connecticut Sky Survey (the BATC survey). The CCD images are taken with the National Astronomical Observatories of China (NAOC) 0.6/0.9m f/3 Schmidt telescope at the Xinglong Observing Station, using a multicolor filter set. The observations reported here were taken on 30 individual nights over the time period 1995 February 5 to 1997 February 19. Spectra of 10 of the brightest HII regions are obtained using the NAOC 2.16m telescope with a Tek 1024x1024 CCD, between 1997 April 9 and 11. The continua of the spectra are calibrated by flux-calibrated images taken from the Schmidt observations. We determine the continuum component of our H{alpha}+[NII] image via interpolation from the more accurately measured backgrounds (M81 starlight) obtained from the two neighboring (in wavelength) BATC filter images. We use the calibrated fluxes of H{alpha}+[NII] emission from the spectra to normalize this interpolated, continuum-subtracted H{alpha}+[NII] image. We estimate the zero-point uncertainty of the measured H{alpha}+[NII] emission flux to be 8%. A catalog of H{alpha}+[NII] fluxes for 456 HII regions is provided, with those fluxes being on a more consistent linear scale than previously available. The logarithmically binned H{alpha}+[NII] luminosity function of HII regions is found to have slope {alpha}=-0.70, consistent with previous results (which allowed {alpha}=-0.5 to -0.8). From the overall H{alpha}+[NII] luminosity of the HII regions, the star formation rate of M81 is found to be ~0.68M_{sun}_/yr, modulo uncertainty with extinction corrections.
936. H{alpha} observations of LSI+61 303
ID:
ivo://CDS.VizieR/J/A+A/559/A87
Title:
H{alpha} observations of LSI+61 303
Short Name:
J/A+A/559/A87
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report 137 spectral observations of the H{alpha} emission line of the radio- and gamma-ray-emitting Be/X-ray binary LSI+61 303 obtained during the period of September 1998 - January 2013. From measuring various H{alpha} parameters, we found that the orbital modulation of the H{alpha} is best visible in the equivalent width ratio EW(B)/EW(R), the equivalent width of the blue hump, and in the radial velocity of the central dip. The periodogram analysis confirmed that the H{alpha} emission is modulated with the orbital and superorbital periods. For the past 20 years the radius of the circumstellar disk is similar to the Roche lobe size at the periastron. It is probably truncated by a 6:1 resonance. The orbital maximum of the equivalent width of H{alpha} emission peaks after the periastron and coincides on average with the X-ray and gamma-ray maxima.
937. H{alpha} observations of UV-selected galaxies
ID:
ivo://CDS.VizieR/J/ApJ/647/128
Title:
H{alpha} observations of UV-selected galaxies
Short Name:
J/ApJ/647/128
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using Halpha spectra of 114 rest-frame UV-selected galaxies at z~2, we compare inferred star formation rates (SFRs) with those determined from the UV continuum luminosity. After correcting for extinction using standard techniques based on the UV continuum slope, we find excellent agreement between the indicators, with <SFR_Ha_>=31M_{sun}_/yr and <SFR_UV_>=29M_{sun}_/yr. The agreement between the indicators suggests that the UV luminosity is attenuated by a typical factor of ~4.5 (ranging from no attenuation to a factor of 100 for the most obscured object in the sample), in good agreement with estimates of obscuration from X-ray, radio, and mid-IR data.
938. H{alpha} photometry of face-on galaxies
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.
939. H{alpha} profiles of Be stars
ID:
ivo://CDS.VizieR/J/ApJS/187/228
Title:
H{alpha} profiles of Be stars
Short Name:
J/ApJS/187/228
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a set of theoretical H{alpha} emission-line profiles of Be stars, created by systematically varying model input parameters over a wide range of accepted values. Models were generated with a non-LTE radiative transfer code that incorporates a non-isothermal disk structure and a solar-type chemical composition. The theoretical H{alpha} emission-line profiles were compared to a large set of Be star spectra with the aim of reproducing their global characteristics. We find that the observed profile shapes cannot be used to uniquely determine the inclination angle of Be star+disk systems. Drastically different profile shapes arise at a given inclination angle as a direct result of the state of the gas, and self-consistent disk physical conditions are therefore crucial for interpreting the observations.
940. H{alpha} spectra of MWC 342 spectra, 2004-2010
ID:
ivo://CDS.VizieR/J/A+A/554/A143
Title:
H{alpha} spectra of MWC 342 spectra, 2004-2010
Short Name:
J/A+A/554/A143
Date:
21 Oct 2021
Publisher:
CDS
Description:
The catalogue presents spectra of MWC 342 (V1972 Cyg) obtained during the period 2004 to 2010 with the Coude spectrograph at the 2m telescope in Ondrejov observatory, Czech Republic, using the SITe CCD (2030x800 pixels, 15um pixel size) in a camera with 700mm focus. The spectral interval along the H{alpha} line covers 6265 to 6765{AA}. The resolving power is this range is R~13000. The data reduction was performed using IRAF. After the bias subtraction, flat-field and overscan correction, the dcr program written by Pych (2004PASP..116..148P) was used for the cosmic ray removal. The spectra subtraction was done by IRAF apall task without using the optimal extraction . The background, together with the night sky lines, is eliminated during spectra subtraction by individual pixel columns. The remaining wavelength calibration, heliocentric correction, and the continuum fitting are also performed using IRAF. The heliocentric correction was applied on the data. Chebyshev polynomial of the third order is used for the spectra normalisation to fit the intervals, which apparently contain no spectral lines. Each continuum interval is split into sub-intervals of five pixels, where the median value is taken for the continuum evaluation. Possible remaining cosmic ray hits thus do not affect continuum normalisation.

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