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Rotation Velocities of Red and Blue Field Horizontal-Branch Stars
We present measurements of the projected stellar rotation velocities(vsini) of a sample of 45 candidate field horizontal-branch (HB) starsspanning a wide range of effective temperatures, from red HB stars withTeff~=5000K to blue HB stars with Teff of 17,000K.Among the cooler blue HB stars (Teff=7500-11500 K), weconfirm prior studies showing that, although a majority of stars rotateat vsini<15kms-1, there exists a subset of ``fastrotators'' with vsini as high as 30-35 km s-1. All but one ofthe red HB stars in our sample have vsini<10kms-1, and noanalogous rotation bimodality is evident. We also identify anarrow-lined hot star (Teff~=16,000K) with enhancedphotospheric metal abundances and helium depletion, similar to theabundance patterns found among hot BHB stars in globular clusters, andfour other stars that may also belong in this category. We discussdetails of the spectral line fitting procedure that we use to deducevsini and explore how measurements of field HB star rotation may shedlight on the issue of HB star rotation in globular clusters.
| A homogeneous catalog of new UBV and H-beta photometry of B- and A-type stars in and around the Scorpius-Centaurus OB association
B- and A-type stars in and near the Sco-Cen OB association areinvestigated with UBV and H-beta photometry to acquire data relevant tothe luminosity function of Sco-Cen. The measurements generally consistof two 10-s integrations of U, B, V, (W, N) filters, and theobservations are corrected iteratively for atmospheric extinction andinstrumental response. The data presented give the mean V magnitude,mean B-V, mean U-B, and the estimated uncertainties for these values.The catalog provides a homogeneous catalog of data for a large fieldwith stellar objects delineating membership to the association Sco-Cenand that affect the luminosity function of the aggregate.
| Catalogue of Hydrogen Line Spectral Profiles of 236 B-Stars A-Stars and F-Stars
Not Available
| The catalogue of equivalent line widths in the spectra of A- and F-stars.
Not Available
| Field horizontal-branch stars at ultraviolet and visual wavelengths
The spectra of 17 field horizontal-branch (FHB) stars observed at about5-A resolution between 1150 and 3200 A with the IUE and about 8-Aresolution between 3600 and 5800 A with the Reticon of Pine BlufObservatory are compared with data of Population I stars of similartemperatures and with theoretical model atmospheres. The FHB stars haveweaker spectral lines and are brighter than Population I stars atwavelengths below 1800 A. The models are too bright below 1600 A toproperly match the Population II star energy distributions. Temperaturesfor the FHB stars which are consistent for the wavelength range observedare obtained.
| High-dispersion spectroscopic investigation of field horizontal-branch, high-luminosity, and main-sequence stars
High-dispersion spectra (12.5 A/mm) were taken of 11 early-type starswith the Cassegrain image-tube spectrograph on the CTIO 4 m telescope,in order to improve previous classifications based on low-dispersionand/or photometric studies. Atmospheric parameters were determined, aswell as interstellar reddenings and radial velocities. Five of the starswere classified as field horizontal-branch stars, two as high-luminositystars, three as main-sequence stars, and one as an RR Lyrae variablestar. Abundances of 11 elements were derived for the five fieldhorizontal-branch stars and for one moderate high-luminosity star. Awide range of variation in (Ca/Fe) was detected, and its implicationsare discussed briefly.
| Scanner observations of field horizontal-branch A stars
Measurements have been conducted regarding the energy distributions of16 field horizontal-branch A stars, plus nine others of miscellaneoustypes, at 20 wavelengths between 3450 and 6970 A using the HCO scannerson 0.9 m telescopes at Kitt Peak and Cerro Tololo Observatories. Theobservations are reported here as absolute energy distributions on thesystem of Hayes and Latham. The (internal) measurement error (std. dev.)is 0.025 mag per observation, averaged over all wavelengths.
| Astrophysical Parameters from Four-Colour Photometry
Not Available
| Discoveries on Southern Objective-Prism Plates. II. New Probable Field Horizontal-Branch Stars
Abstract image available at:http://adsabs.harvard.edu/abs/1971PASP...83...98M
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| Takýmyýldýz: | Terazi |
| Sað Açýklýk: | 14h47m02.34s |
| Yükselim: | -16°28'24.0" |
| Görünürdeki Parlaklýk: | 9.359 |
| özdevim Sað Açýklýk: | -19.7 |
| özdevim Yükselim: | -1.8 |
| B-T magnitude: | 9.824 |
| V-T magnitude: | 9.398 |
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