- ID:
- ivo://CDS.VizieR/J/ApJS/242/11
- Title:
- H{alpha} imaging survey of the 40% ALFALFA HI LSBGs
- Short Name:
- J/ApJS/242/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a narrow H{alpha}-band imaging survey of 357 low surface brightness galaxies (LSBGs) that are selected from the spring sky region of the 40% Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) HI Survey. All the H{alpha} images are obtained from the 2.16m telescope, operated by the Xinglong Observatory of the National Astronomical Observatories, Chinese Academy of Sciences. We provide the H{alpha} fluxes and derive the global star formation rates (SFRs) of LSBGs after the Galactic extinction, internal extinction, and [NII] contamination correction. Compared to normal star-forming galaxies, LSBGs have a similar distribution in the HI surface density ({Sigma}HI), but their SFRs and star formation surface density ({Sigma}SFR) are much lower. Our results show that the gas-rich LSBGs selected from the ALFALFA survey obviously deviate from the Kennicutt-Schmidt law, in the relation between the star formation surface density ({Sigma}SFR) and the gas surface density ({Sigma}gas). However, they follow the extended Schmidt law well when taking the stellar mass of the galaxy into consideration.
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1482. H-alpha in Abell 2390
- ID:
- ivo://CDS.VizieR/J/MNRAS/318/703
- Title:
- H-alpha in Abell 2390
- Short Name:
- J/MNRAS/318/703
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photometry is tabulated for 1189 galaxies in 19 OSIS-V (CFHT) images in the direction of the galaxy cluster Abell 2390. The images cover 270 sq. deg., and extend out to the virial radius of the cluster. Three narrow filters are used to determine the flux above the continuum between wavelengths 7897 and 8245 {AA}, corresponding to H-alpha at 0.2033<z<0.2563. The absolute flux values are uncertain by about 30% due to zero point uncertainty; we also tabulate the equivalent width which is independent of this zero point. Only strong emission line cluster members (equivalent width greater than about 50{AA}) are detectable, by design. Galaxies with spectra available from the CNOC survey (Abraham=1996ApJ...471..694A) are identified.
- ID:
- ivo://CDS.VizieR/J/MNRAS/447/1126
- Title:
- Halpha measurements in Abell 2465
- Short Name:
- J/MNRAS/447/1126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the star formation rate and its location in the major merger cluster Abell 2465 at z=0.245. Optical properties of the cluster are described in. Measurements of the H{alpha} and infrared dust emission of galaxies in the cluster were made with an interference filter centred on the redshifted line at a wavelength of 817 nm and utilized data from the Wide-field Infrared Survey Explorer satellite 12{mu}m band. Imaging in the Johnson U and B bands was obtained, and along with Sloan Digital Sky Survey u and r was used to study the blue fraction, which appears enhanced, as a further signature of star formation in the cluster. Star formation rates were calculated using standard calibrations. The total star formation rate normalized by the cluster mass, {Sigma}SFR/M_cl_ compared to compilations for other clusters indicate that the components of Abell 2465 lie above the mean z and M_cl_ relations, suggestive that interacting galaxy clusters have enhanced star formation. The projected radial distribution of the star-forming galaxies does not follow an NFW profile and is relatively flat indicating that fewer star-forming galaxies are in the cluster centre. The morphologies of the H{alpha} sources within R_200_ for the cluster as a whole indicate that many are disturbed or merging, suggesting that a combination of merging or harassment is working.
- 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.
- 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.
- ID:
- ivo://CDS.VizieR/II/24
- Title:
- H-{alpha} Photometry of Northern Late-Type Stars I.
- Short Name:
- II/24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations are presented of the strength of the H-{alpha} absorption line in the spectra of approximately 600 northern F, G and K stars of differing luminosities and chemical compositions. Most of the stars in this catalogue were previously observed by Griffin and Redman (1960MNRAS.120..287G), Deeming (1960MNRAS.121...52D), and Griffin (1961MNRAS.122..181G). Data given in this catalog include HD number, MK spectral classification, high velocity, (B-V) color index, magnesium b ratio, sodium D line ratio and H-{alpha} ratio.
- ID:
- ivo://CDS.VizieR/II/22
- Title:
- H{alpha} photometry of Southern F-G dwarfs
- Short Name:
- II/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- H{alpha} photometry is presented for 172 southern F, G, and K type stars, mostly of luminosity classes V and IV. The bands measured, using a spectroscopic resolution of 3.4{AA}/mm, were: H{alpha}: 6546.5-6582.5{AA} comparison regions: 6469.0-6505.0{AA} and 6624.0-6660.0{AA}.
- ID:
- ivo://CDS.VizieR/J/ApJ/890/86
- Title:
- H{alpha} spectra & V-band photometry of {delta} Sco
- Short Name:
- J/ApJ/890/86
- Date:
- 04 Dec 2021
- Publisher:
- CDS
- Description:
- We model the circumstellar disk of {delta} Sco using the three-dimensional Monte Carlo radiative transfer code HDUST in order to quantify the large-scale changes in the disk through the years 2000-2018, and to see if these changes can be attributed to the secondary star affecting the disk throughout its orbit. We determine our best-fitting models through matching simulated observations to actual H{alpha} spectroscopy and V-band photometric observations. Our modeling results confirm previous findings that the disk of {delta}Sco was forming early in the century. We also find a period of disk dissipation when the companion is at apastron, as well as a significant growth of the disk between 2009 and 2011, prior to the periastron of 2011. Due to the steady-state nature of the disk after 2011, it is difficult to say whether the variations seen are due to the effect of the close passage of the binary companion.
- 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/ApJS/208/28
- Title:
- H{alpha} survey in the ONC
- Short Name:
- J/ApJS/208/28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from an H{alpha} emission line survey in a 1 deg^2^ area centered on the Orion Nebula Cluster, obtained with the Wide Field Grism Spectrograph 2 on the 2.2 m telescope of the University of Hawaii. We identified 587 stars with H{alpha} emission, 99 of which, located mainly in the outer regions of the observed area, have not appeared in previous H{alpha} surveys. We determined the equivalent width (EW) of the line and, based on this, classified 372 stars as classical T Tauri stars (CTTSs) and 187 as weak-line T Tauri stars (WTTSs). Simultaneous r', i' photometry indicates a limiting magnitude of r' ~ 20 mag, but the sample is incomplete at r' > 17 mag. The surface distribution of the H{alpha} emission stars reveals a clustered population and a dispersed population, the former consisting of younger and more massive young stars than the latter. Comparison of the derived EWs with those found in the literature indicates variability of the H{alpha} line. We found that the typical amplitudes of the variability are not greater than a factor of two to three in most cases. We identified a subgroup of low-EW stars with infrared signatures indicative of optically thick accretion disks. We studied the correlations between the EW and other properties of the stars. Based on literature data, we examined several properties of our CTTS and WTTS subsamples and found significant differences in mid-infrared color indices, average rotational periods, and spectral energy distribution characteristics of the subsamples.
