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A GLIMPSE into the Nature of Galactic Mid-IR Excesses
We investigate the nature of the mid-IR excess for 31 intermediate-massstars that exhibit an 8 μm excess in either the Galactic LegacyInfrared Mid-Plane Survey Extraordinaire or the Mid-Course SpaceExperiment using high-resolution optical spectra to identify starssurrounded by warm circumstellar dust. From these data we determineprojected stellar rotational velocities and estimate stellar effectivetemperatures for the sample. We estimate stellar ages from thesetemperatures, parallactic distances, and evolutionary models. Using MIPS[24] measurements and stellar parameters we determine the nature of theinfrared excess for 19 GLIMPSE stars. We find that 15 stars exhibitHα emission and four exhibit Hα absorption. Assuming thatthe mid-IR excesses arise in circumstellar disks, we use the Hαfluxes to model and estimate the relative contributions of dust andfree-free emission. Six stars exhibit Hα fluxes that implyfree-free emission can plausibly explain the infrared excess at [24].These stars are candidate classical Be stars. Nine stars exhibitHα emission, but their Hα fluxes are insufficient to explainthe infrared excesses at [24], suggesting the presence of acircumstellar dust component. After the removal of the free-freecomponent in these sources, we determine probable disk dust temperaturesof Tdisk~=300-800 K and fractional infrared luminosities ofLIR/L*~=10-3. These nine stars may bepre-main-sequence stars with transitional disks undergoing diskclearing. Three of the four sources showing Hα absorption exhibitcircumstellar disk temperatures ~=300-400 K,LIR/L*~=10-3, IR colors K-[24]<3.3,and are warm debris disk candidates. One of the four Hα absorptionsources has K-[24]>3.3 implying an optically thick outer disk and isa transition disk candidate.
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| The local system of early type stars - Spatial extent and kinematics
Published uvby and H-beta photometric data and proper motions arecompiled and analyzed to characterize the structure and kinematics ofthe bright early-type O-A0 stars in the solar vicinity, with a focus onthe Gould belt. The selection and calibration techniques are explained,and the data are presented in extensive tables and graphs and discussedin detail. The Gould belt stars of age less than 20 Myr are shown togive belt inclination 19 deg to the Galactic plane and node-lineorientation in the direction of Galactic rotation, while the symmetricaldistribution about the Galactic plane and kinematic properties (purecircular differential rotation) of the belt stars over 60 Myr oldresemble those of fainter nonbelt stars of all ages. The unresolveddiscrepancy between the expansion observed in the youngest nearby starsand the predictions of simple models of expansion from a point isattributed to the inhomogeneous distribution of interstellar matter.
| Radial velocities for early type stars in six galactic regions
Coudespectroscopy has been carried out for 353 stars of spectral typesB0-A0 and V magnitudes between 6.5 and 10.8 m, selected in six regions(three northern and three southern) close to the galactic plane at thegalactic longitudes 135, 175, 315 and 350 deg. The radial velocitieswere obtained by cross-correlating each spectrogram with a referencespectrogram giving an internal error of 1.4 km/s.
| A Catalogue of Be-Stars
Not Available
| Four-colour and H-beta photometry for early type stars in three southern galactic regions
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1980A&AS...41...85L&db_key=AST
| Observations of southern emission-line stars
A catalog of 1929 stars showing H-alpha emission on photographic platesis presented which covers the entire southern sky south of declination-25 deg to a red limiting magnitude of about 11.0. The catalog providesprevious designations of known emission-line stars equatorial (1900) andgalactic coordinates, visual and photographic magnitudes, H-alphaemission parameters, spectral types, and notes on unusual spectralfeatures. The objects listed include 16 M stars, 25 S stars, 37 carbonstars, 20 symbiotic stars, 40 confirmed or suspected T Tauri stars, 16novae, 14 planetary nebulae, 11 P Cygni stars, 9 Bep stars, 87 confirmedor suspected Wolf-Rayet stars, and 26 'peculiar' stars. Two new Tassociations are discovered, one in Lupus and one in Chamaeleon. Objectswith variations in continuum or H-alpha intensity are noted, and thedistribution by spectral type is analyzed. It is found that the skydistribution of these emission-line stars shows significantconcentrations in the region of the small Sagittarius cloud and in theCarina region.
| A spectral survey of the southern Milky Way 1 : general description and catalogue 1 (l=306 -318 degrees).
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974A&AS...16..445S&db_key=AST
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Osservazione e dati astrometrici
| Costellazione: | Centauro |
| Ascensione retta: | 13h55m53.89s |
| Declinazione: | -61°30'13.5" |
| Magnitudine apparente: | 9.018 |
| Distanza: | 10000000 parsec |
| Moto proprio RA: | -9.7 |
| Moto proprio Dec: | -5.7 |
| B-T magnitude: | 9.081 |
| V-T magnitude: | 9.024 |
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