- ID:
- ivo://CDS.VizieR/J/AJ/130/1805
- Title:
- H{alpha} emission stars in NGC 2362
- Short Name:
- J/AJ/130/1805
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An H{alpha} emission survey of the young cluster NGC 2362 resulted in the detection of 130 H{alpha} emission stars in an 11'x11' field approximately centered on the fourth magnitude O9 Ib multiple star {tau} CMa. The survey was carried out using the wide-field grism spectrograph on the University of Hawaii 2.2m telescope and the Gemini Multi-Object Spectrograph (GMOS) on Gemini North. Deep optical VR_C_I_C_ (to V~23.0) and near-infrared (NIR) photometry (JHK) to K~16 were obtained for several fields within the cluster. Spectra covering the 6000-8000{AA} region at a resolution of R~3000 (adequate for the determination of LiI{lambda}6708 line strengths) were also acquired for ~200 pre-main-sequence (PMS) candidates with GMOS.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/II/309
- Title:
- H{alpha} emission stars in the Orion Nebula
- Short Name:
- II/309
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog of 534 H{alpha} emission lines stars in the region of the Orion Nebula (5{deg}x5{deg}) is presented, an the basis of 240 "new" H{alpha} stars found on Tonantzintla spectral plates and previous known H{alpha} emission stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/416/2041
- Title:
- H{alpha} emitters at z=2.23
- Short Name:
- J/MNRAS/416/2041
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a narrow-band (H_2_S1, {lambda}_c_=2.121um, {delta}{lambda}=0.021um) imaging search with Wide Field Camera/United Kingdom Infrared Telescope for H{alpha} emitters (HAEs) around several potential signposts of rare (~10^-7^-10^-8^ comoving Mpc^-3^) overdense regions at z=2.23: an overdensity of quasi-stellar objects [QSOs; 2dF QSO Redshift Survey (2QZ) cluster], a powerful, high-redshift radio galaxy (HzRG) and a concentration of submillimetre galaxies (SMGs) and optically faint radio galaxies (OFRGs). In total, we detect 137 narrow-band emitter candidates down to emission-line fluxes of 0.5-1x10^-16^erg/s/cm^2^, across a total area of 0.56deg^2^ (2.1x10^5^ comoving Mpc^3^ at z=2.23) in these fields.
- ID:
- ivo://CDS.VizieR/J/ApJS/175/128
- Title:
- H{alpha} emitting galaxies in COSMOS-2 field
- Short Name:
- J/ApJS/175/128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To derive a new H{alpha} luminosity function and to understand the clustering properties of star-forming galaxies at z~0.24, we have made a narrowband imaging survey for H{alpha}-emitting galaxies in the Hubble Space Telescope (HST) COSMOS 2 square degree field. We used the narrowband filter NB816 ({lambda}_c_=8150{AA}, {Delta}{lambda}=120{AA}) and sampled H{alpha} emitters with EW_obs_(H{alpha}+[NII])>12{AA} in a redshift range between z=0.233 and 0.251 corresponding to a depth of 70Mpc. We obtained 980 H{alpha}-emitting galaxies in a sky area of 5540arcmin^2^, corresponding to a survey volume of 3.1x10^4^Mpc^3^.
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/384/383
- Title:
- H{alpha} galaxies in Abell 1367 and Coma
- Short Name:
- J/A+A/384/383
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a deep wide field H{alpha} imaging survey of the central regions of the two nearby clusters of galaxies Coma and Abell 1367, taken with the WFC at the Prime Focus at the NT 2.5m telescope located at Observatorio de El Roque de los Muchachos (La Palma), on April 26th and 28th 2000. We determine for the first time the Schechter parameters of the H{alpha} luminosity function (LF) of cluster galaxies.
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/546/A77
- Title:
- H{alpha} images of HD93521
- Short Name:
- J/A+A/546/A77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Owing to its unusual location and its isolation, the nature of the high Galactic latitude O9.5 Vp object HD 93521 is still uncertain. We have collected X-ray and optical observations to characterize the star and its surroundings.
- ID:
- ivo://CDS.VizieR/J/A+A/659/A46
- Title:
- Halpha images of 6 lenticular galaxies
- Short Name:
- J/A+A/659/A46
- Date:
- 04 Mar 2022 00:51:50
- Publisher:
- CDS
- Description:
- As part of the Virgo Cluster Survey Tracing Ionised Gas Emission, a blind narrow-band H{alpha}+[NII] imaging survey of the Virgo cluster carried out with MegaCam at the CFHT, we discovered eight massive (10^10^<~M_star_<~10^11^M_{sun}_) lenticular galaxies with prominent ionised gas emission features in their inner (a few kiloparsec) regions. These features are either ionised gas filaments similar to those observed in cooling flows (two galaxies), or they are thin discs with sizes 0.7<~R(H{alpha})<~2.0kpc (six galaxies), thus significantly smaller than those of the stellar disc (R(H{alpha})~=7-22%R_iso_(r)). The morphological properties of these discs are similar to those of the dust seen in absorption in high-resolution HST images. Using a unique set of multifrequency data, including new or archival ASTROSAT/UVIT, GALEX, HST, CFHT, Spitzer, and Herschel imaging data, combined with IFU (MUSE, ALMA) and long-slit (SOAR) spectroscopy, we show that while the gas that is located within these inner discs is photoionised by young stars, which signals ongoing star formation, the gas in the filamentary structures is shock ionised. The star formation surface brightness of these discs is similar to that observed in late-type galaxies. Because of their reduced size, however, these lenticular galaxies are located below the main sequence of unperturbed or cluster star-forming systems. By comparing the dust masses measured from absorption maps in optical images, from the Balmer decrement, or estimated by fitting the UV-to-far-IR spectral energy distribution of the target galaxies, we confirm that the dust masses derived from optical attenuation maps are heavily underestimated because of geometrical effects due to the relative distribution of the absorbing dust and the emitting stars. We also show that these galaxies have gas-to-dust ratios of G/D=~80_30_^320^, and that the star formation within these discs follows the Schmidt relation, but with an efficiency that is reduced by a factor of ~2.5. Using our unique set of multifrequency data, we discuss the possible origin of the ionised gas in these objects, which suggests multiple and complex formation scenarios for massive lenticular galaxies in clusters.
- ID:
- ivo://CDS.VizieR/J/A+A/587/A135
- Title:
- Halpha images of NGC 6334 and NGC 6357
- Short Name:
- J/A+A/587/A135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze the Halpha emission of the star-forming region NGC 6334 and NGC 6357 with the aim to precise/determine the nature of the HII regions.
