- ID:
- ivo://CDS.VizieR/J/A+AS/137/495
- Title:
- Halpha Catalogue of HCG Galaxies
- Short Name:
- J/A+AS/137/495
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present H{alpha} photometry for a sample of 95 galaxies in Hickson Compact Groups (Cat. <VII/213>) obtained from observations of 31 groups. The Catalogue lists isophotal and adaptive aperture (Kron aperture) flux measurements for about 75% of the accordant galaxies inside the observed HCGs, 22 out of which are upper limits. Non standard data reduction procedures have been used to obtain the continuum subtracted H{alpha} images for each HCG of the target sample. Flux calibration has also been performed in order to obtain H{alpha} luminosities for the whole sample. Both the data reduction and calibration procedures are carefully described in the paper.
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- ID:
- ivo://CDS.VizieR/J/A+A/629/A102
- Title:
- Halpha data cube of Stephan's Quintet
- Short Name:
- J/A+A/629/A102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stephan's Quintet (SQ), the prototypical compact group of galaxies in the local Universe, has been observed with the imaging Fourier transform spectrometer SITELLE, attached to the Canada-France-Hawaii- Telescope, to perform a deep search for intergalactic star-forming emission. In this paper we present the extended ionised gaseous structures detected and analyse their kinematical properties. The large field of view (11'x11') and the spectral ranges of SITELLE have allowed a thorough study of the entire galaxy system, its interaction history and the main properties of the ionised gas. The observations have revealed complex three-dimensional strands in SQ seen for the first time, as well as the spatially resolved velocity field for a new SQ dwarf galaxy (M82-like) and the detailed spectral map of NGC7320c, confirming its AGN nature. A total of 175 SQ Halpha emission regions have been found, 22 of which present line profiles with at least two kinematical components. We studied 12 zones and 28 sub-zones in the SQ system in order to define plausible physical spatial connections between its different parts in the light of the kinematical information gathered. In this respect we have found five velocity systems in SQ: i) v=[5600-5900]km/s associated with the new intruder and the southern debris region; ii) v=[5900-6100]km/s, associated with the north starburst A and south starburst A and the strands connected to these zones; iii) v=[6100-6600]km/s, associated with the strands from the large-scale shock region (LSSR); iv) v=[6600-6800]km/s, associated with the young tidal tail, the starburst A (SQA), NGC7319, and the NGC7319 north lobe; and v) v=[6800-7000]km/s, associated with the strands seen connecting LSSR with SQA. We fail to detect ionised gas emission in the old tail, neither in the vicinity of NGC7318A nor in NGC7317, and the connection between NGC7319 north lobe and SQA cannot be confirmed. Conversely, a clear gaseous bridge has been confirmed both spatially and kinematically between the LSSR zone and the NGC7319 AGN nucleus. Finally, a larger scale, outer rim winding the NGC7318B/A system clockwise north-west to south-east has been highlighted in continuum and in H{alpha}. This structure may be reminiscent of a sequence of a previously proposed scenario for SQ a sequence of individual interactions.
- ID:
- ivo://CDS.VizieR/J/ApJ/630/206
- Title:
- H{alpha} data for 3 EDisCS galaxy clusters
- Short Name:
- J/ApJ/630/206
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present H{alpha}-derived SFRs for three z~0.75 galaxy clusters. Our 1{sigma} flux limit corresponds to a star formation rate (SFR) of 0.10-0.24h^-2^_100_M_{Sun}/yr, and our minimum reliable H{alpha}+[NII] rest-frame equivalent width is 10{AA}. We show that H narrowband imaging is an efficient method for measuring star formation in distant clusters.
- ID:
- ivo://CDS.VizieR/J/A+A/509/A11
- Title:
- H{alpha} emission-line objects in SMC clusters
- Short Name:
- J/A+A/509/A11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Slitless CCD spectra were obtained covering the bulk (about 3 square degrees) of the Small Magellanic Cloud. For H{alpha} line-emission twice as strong as the ambient continuum, the survey is complete to spectral type B2/B3 on the main sequence. About 8120 spectra of 4437 stars were searched for emission lines in 84 open clusters, and 370 emission-line stars were found, among them at least 231 close to the main sequence. For 176 of them, photometry is available from the OGLE database. For comparison with a higher-metallicity environment, the Galactic sample of the photometric H{alpha} survey by McSwain & Gies (2005, Cat. <J/ApJS/161/118>) was used. Among early spectral sub-types, Be stars are more frequent by a factor ~3-5 in the SMC than in the Galaxy. The distribution with spectral type is similar in both galaxies, i.e., not strongly dependent on metallicity. The fraction of Be stars does not seem to vary with local star density. The Be phenomenon mainly sets in towards the end of the main-sequence evolution (this trend may be more pronounced in the SMC); but some Be stars already form with Be-star characteristics. In small subsamples (such as single clusters), even if they appear identical, the fraction of emission-line stars can deviate drastically from the mean. In all probability, the fractional critical angular rotation rate, OMC, is one of the main parameters governing the occurrence of the Be phenomenon. If the Be character is only acquired during the course of evolution, the key circumstance is the evolution of OMC, which is not only dependent on metallicity but differently so for different mass ranges. As a result, even if the Be phenomenon is driven basically by a single parameter (namely OMC), it can assume a complex multi-parametric appearance. The large cluster-to-cluster differences, which seem stronger than all other variations, serve as a caveat that this big picture may undergo significant second-order modulations (e.g., pulsations, initial angular momentum, etc).
- ID:
- ivo://CDS.VizieR/J/MNRAS/384/1277
- Title:
- H{alpha} emission line sources from IPHAS
- Short Name:
- J/MNRAS/384/1277
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first catalogue of point-source H{alpha} emission line objects selected from the INT/WFC Photometric H{alpha} Survey of the Northern Galactic Plane (IPHAS). In total, our catalogue contains 4853 point sources that exhibit strong photometric evidence for H{alpha} emission. The catalogue is a conservative subset of the emitters present in IPHAS and it is likely that there are many more H{alpha} emitters present in the area of the Galactic Plane that IPHAS observes. Our selection criteria are designed to be conservative (rather than complete) in order to avoid a significant number of false positives in the catalogue. In line with this, we find that of the ~300 catalogue sources for which we have preliminary spectroscopic follow-up observations, more than 95% are confirmed as genuine emission-line sources.
- ID:
- ivo://CDS.VizieR/J/A+A/630/A90
- Title:
- Halpha emission-line stars in Canis Major
- Short Name:
- J/A+A/630/A90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A deep objective-prism survey for H-alpha emission stars towards the Canis Major star-forming clouds was performed. A total of 398 Halpha emitters were detected, 353 of which are new detections. There is a strong concentration of these H-alpha emitters towards the molecular clouds surrounding the CMa OB1 association, and it is likely that these stars are young stellar objects recently born in the clouds. An additional population of H-alpha emitters is scattered all across the region, and probably includes unrelated foreground dMe stars and background Be stars. About 90% of the H-alpha emitters are detected by WISE, of which 75% was detected with usable photometry. When plotted in a WISE colour-colour diagram it appears that the majority are Class II YSOs. Coordinates and finding charts are provided for all the new stars, and coordinates for all the detections. We searched the Gaia-DR2 catalogue and from 334 Halpha emission stars with useful parallaxes, we selected a subset of 98 stars that have parallax errors of less than 20% and nominal distances in the interval 1050 to 1350pc that surrounds a strong peak at 1185pc in the distance distribution. Similarly, Gaia distances were obtained for 51 OB-stars located towards Canis Major and selected with the same parallax errors as the H-alpha stars. We find a median distance for the OB stars of 1182pc, in excellent correspondence with the distance from the H-alpha stars. Two known runaway stars are confirmed as members of the association. Finally, two new Herbig-Haro objects are identified.
- ID:
- ivo://CDS.VizieR/J/AJ/134/2474
- Title:
- H{alpha} emission-line stars in 7 dwarfs galaxies
- Short Name:
- J/AJ/134/2474
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe a search for H{alpha} emission-line stars in M31, M33, and seven dwarfs in or near the Local Group (IC 10, NGC 6822, WLM, Sextans B, Sextans A, Pegasus, and the Phoenix dwarf) using interference filter imaging with the KPNO and CTIO 4m telescopes and Mosaic cameras. The survey is aimed primarily at identifying new luminous blue variables (LBVs) from their spectroscopic similarity to known LBVs, avoiding the bias toward photometric variability, which may require centuries to manifest itself if LBVs go through long quiescent periods. Follow-up spectroscopy with WIYN confirms that our survey detected a wealth of stars whose spectra are similar to the known LBVs.
- ID:
- ivo://CDS.VizieR/J/A+A/570/A30
- Title:
- H{alpha} emission-line stars in M42
- Short Name:
- J/A+A/570/A30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a deep survey of H-alpha emission-line stars in the M42 region using wide-field objective prism films. A total of 1699 H{alpha} emission-line stars were identified, of which 1025 were previously unknown, within an area of 5.5{deg}x5.5{deg} centred on the Trapezium Cluster. We present H-alpha strength estimates, positions, and JHKs photometry extracted from 2MASS, and comparisons to previous surveys. The spatial distribution of the bulk of the stars follows the molecular cloud as seen in CO and these stars are likely to belong to the very young population of stars associated with the Orion Nebula Cluster. Additionally, there is a scattered population of H-alpha emission-line stars distributed all over the region surveyed, which may consist partly of foreground stars associated with the young NGC 1980 cluster, as well as some foreground and background dMe or Be stars. The present catalogue adds a large number of candidate low-mass young stars belonging to the Orion population, selected independently of their infrared excess or X-ray emission.
- ID:
- ivo://CDS.VizieR/J/AJ/127/1117
- Title:
- Halpha emission-line stars in NGC2264
- Short Name:
- J/AJ/127/1117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a deep survey of H{alpha} emission-line stars in the NGC 2264 region using wide-field objective prism films. We find 357 H{alpha} emission-line stars, of which 113 were previously detected, within an area of 3{deg}x3{deg} centered on the Cone Nebula, with a majority of stars being concentrated in a dense cluster at the center of the region. We present a large-scale CO map of NGC 2264 and find a strong correlation between the cluster of H{alpha} emission-line stars and the most massive core in the cloud complex. A more extended halo of stars poorly correlated with the gas may represent stars that have drifted away from their birth place, suggesting that star formation has taken place in NGC 2264 for several million years.
- ID:
- ivo://CDS.VizieR/J/ApJ/669/L33
- Title:
- H{alpha} emission sources in h and {chi} Per
- Short Name:
- J/ApJ/669/L33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of accretion disks associated with ~13Myr old intermediate/low-mass stars in h and {chi} Persei. Optical spectroscopy of ~5000 stars in these clusters and a surrounding halo population reveal 32 A-K stars with Halpha emission. Matching these stars with 2MASS and optical photometry yields 25 stars with the highest probability of cluster membership and EW(Halpha)>=5{AA}. Sixteen of these sources have EW(Halpha)>=10{AA}.
