- ID:
- ivo://CDS.VizieR/J/ApJS/167/177
- Title:
- Emission lines of evolving HII regions
- Short Name:
- J/ApJS/167/177
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We build, as far as theory will permit, self-consistent model HII regions around central clusters of aging stars. These produce strong emission line diagnostics applicable to either individual HII regions in galaxies or to the integrated emission line spectra of disk or starburst galaxies. The models assume that the expansion and internal pressure of individual HII regions is driven by the net input of mechanical energy from the central cluster, be it through winds or supernova events. This eliminates the ionization parameter as a free variable, replacing it with a parameter that depends on the ratio of the cluster mass to the pressure in the surrounding interstellar medium. These models explain why HII regions with low abundances have high excitation and demonstrate that at least part of the warm ionized medium is the result of overlapping faint, old, large, and low-pressure HII regions. We present line ratios (at both optical and IR wavelengths) that provide reliable abundance diagnostics for both single HII regions or for integrated galaxy spectra, and we find a number that can be used to estimate the mean age of the cluster stars exciting individual HII regions.
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- ID:
- ivo://CDS.VizieR/J/ApJ/599/886
- Title:
- Emission lines of radio-loud AGN
- Short Name:
- J/ApJ/599/886
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the completion of a survey of radio-loud active galactic nuclei (AGNs) begun in an earlier paper (Eracleous & Halpern, 1994ApJS...90....1E) with the main goal of finding and studying broad, double-peaked Balmer lines. We present H{alpha} spectra of 13 more broad-lined objects, including three with double-peaked H{alpha} profiles. The final sample includes 106 radio-loud AGNs. In our final census 20% of objects have H{alpha} lines with double peaks or twin shoulders (the "double-peaked emitters"), and of these 60% (the disklike emitters) can be fitted quite well with a model attributing the emission to a circular, relativistic, Keplerian disk. In four objects where broad H{beta} and Mg II lines have been observed, we compare the profiles with models of photoionized accretion disks and find them to be in reasonable agreement.
- ID:
- ivo://CDS.VizieR/J/A+A/419/215
- Title:
- Emission lines of Sr filament near {eta} Car
- Short Name:
- J/A+A/419/215
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained deep spectra from 1640 to 10100{AA} with the Space Telescope Imaging Spectrograph (STIS) of the strontium filament, a largely neutral emission nebulosity lying close to the very luminous star Eta Carinae and showing an uncommon spectrum. Over 600 emission lines, both permitted and forbidden, have been identified.
- ID:
- ivo://CDS.VizieR/III/203
- Title:
- Emission Lines of the Planetary Nebulae
- Short Name:
- III/203
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The relative intensities of emission lines in the spectra of 32 planetary nebulae in the 3700-7300{AA} region are presented. The spectral observations have been carried out using slit spectrograph with three-cascades image-tube, attached to 70-cm reflector (Alma-Ata). The spectral region is 3700-8500{AA}. The dispersion in the range of 12-200{AA}/mm. The spectral resolution is 0.8-13{AA} in dependence on the dispersion. The errors are less than 10% for the bright lines, 10-15% for the moderate lines and 25-50% for the faintest lines. All measured line intensities were normalised to I(Hbeta)=100.
- ID:
- ivo://CDS.VizieR/J/A+A/631/A118
- Title:
- Emission-line sources MUSE spectral catalogue
- Short Name:
- J/A+A/631/A118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Globular clusters produce many exotic stars due to a much higher frequency of dynamical interactions in their dense stellar environments. Some of these objects were observed together with several hundred thousand other stars in our MUSE survey of 26 Galactic globular clusters. Assuming that at least a few exotic stars have exotic spectra (i.e. spectra that contain emission lines), we can use this large spectroscopic data set of over a million stellar spectra as a blind survey to detect stellar exotica in globular clusters. To detect emission lines in each spectrum, we modelled the expected shape of an emission line as a Gaussian curve. This template was used for matched filtering on the differences between each observed 1D spectrum and its fitted spectral model. The spectra with the most significant detections of H{alpha} emission are checked visually and cross-matched with published catalogues. We find 156 stars with H{alpha} emission, including several known cataclysmic variables (CV) and two new CVs, pulsating variable stars, eclipsing binary stars, the optical counterpart of a known black hole, several probable sub-subgiants and red stragglers, and 21 background emission-line galaxies. We find possible optical counterparts to 39 X-ray sources, as we detected H_alpha emission in several spectra of stars that are close to known positions of Chandra X-ray sources. This spectral catalogue can be used to supplement existing or future X-ray or radio observations with spectra of potential optical counterparts to classify the sources.
- ID:
- ivo://CDS.VizieR/J/ApJ/832/118
- Title:
- Emission-line spectroscopy in NGC 891
- Short Name:
- J/ApJ/832/118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The observed scale heights of extraplanar diffuse ionized gas (eDIG) layers exceed their thermal scale heights by a factor of a few in the Milky Way and other nearby edge-on disk galaxies. Here, we test a dynamical equilibrium model of the eDIG layer in NGC 891, where we ask whether the thermal, turbulent, magnetic field, and cosmic-ray pressure gradients are sufficient to support the layer. In optical emission-line spectroscopy from the SparsePak integral field unit on the WIYN 3.5m telescope, the H{alpha} emission in position-velocity space suggests that the eDIG is found in a ring between galactocentric radii of R_min_<=R<=8kpc, where R_min_>=2kpc. We find that the thermal ({sigma}_th_=11km/s) and turbulent ({sigma}_turb_=25km/s) velocity dispersions are insufficient to satisfy the hydrostatic equilibrium equation given an exponential electron scale height of h_z_=1.0kpc. Using a literature analysis of radio continuum observations from the CHANG-ES survey, we demonstrate that the magnetic field and cosmic-ray pressure gradients are sufficient to stably support the gas at R>=8kpc if the cosmic rays are sufficiently coupled to the system ({gamma}_cr_=1.45). Thus, a stable dynamical equilibrium model is viable only if the eDIG is found in a thin ring around R=8kpc, and nonequilibrium models such as a galactic fountain flow are of interest for further study.
- ID:
- ivo://CDS.VizieR/J/A+AS/102/451
- Title:
- Emission-line stars and PNe in the SMC
- Short Name:
- J/A+AS/102/451
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An objective-prism survey of the Small Magellanic Cloud (SMC) has been performed through an H-{alpha} + [NII] interference filter, using the 90cm Curtis Schmidt telescope of Cerro Tololo. 1898 emission-line objects have been detected in the main body of this galaxy, almost quadrupling the number of those found in the same region by the previous objective-prism surveys. Among these objects are newly discovered planetary nebulae, compact HII regions and late-type stars. Continuum intensity, as well as the shape and relative strength of the H-{alpha} emission-line have been estimated; coordinates, cross-identifications for the listed objects are provided. The original paper contains in addition finding charts.
- ID:
- ivo://CDS.VizieR/J/PASJ/60/739
- Title:
- Emission-line stars in the W5E HII region
- Short Name:
- J/PASJ/60/739
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have made a new survey of emission-line stars in the W5 E HII region to investigate the population of PMS stars near the OB stars by using the Wide Field Grism Spectrograph 2 (WFGS2). A total of 139 Halpha emission stars were detected and their g'i'-photometry was performed. Their spatial distribution shows three aggregates, i.e., two aggregates near the bright-rimmed clouds at the edge of the W5 E HII region (BRC 13 and BRC 14) and one near the exciting O7V star. The age and mass of each Halpha star were estimated from an extinction-corrected color-magnitude diagram and theoretical evolutionary tracks. We found, for the first time in this region, that the young stars near the exciting star are systematically older (4Myr) than those near the edge of the HII region (1Myr). This result supports that the formation of stars proceeds sequentially from the center of HII region to the eastern bright rim. We further suggest a possibility that the birth of low-mass stars near the exciting star of the HII region precedes the production of massive OB stars in the pre-existing molecular cloud.
- ID:
- ivo://CDS.VizieR/J/A+AS/104/233
- Title:
- Emission-line stars in Vela Molecular Ridge
- Short Name:
- J/A+AS/104/233
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/V/73A
- Title:
- Emission-Line Stars of the Orion Population
- Short Name:
- V/73A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This Catalog lists 735 pre-main sequence stars, members of the Orion Population, that have been observed with slit spectrographs or at equivalent resolution. It is intended to replace the Second Catalog of Herbig and Rao (1972). It gives accurate coordinates (many determined especially for this Catalog), light ranges for known variables, UBVRI data near maximum light, references to ultraviolet, X-ray and radio observations and to light curves, value of v sin i and the radial velocity when known, spectral type, equivalent width of the H-alpha emission line, references to spectral reproductions or scans and spectroscopic studies and to identification charts, and a classification (as a T Tau star, FU Ori object, etc.)