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מאמרים קשורים
Hipparcos red stars in the HpV_T2 and V I_C systems
For Hipparcos M, S, and C spectral type stars, we provide calibratedinstantaneous (epoch) Cousins V - I color indices using newly derivedHpV_T2 photometry. Three new sets of ground-based Cousins V I data havebeen obtained for more than 170 carbon and red M giants. These datasetsin combination with the published sources of V I photometry served toobtain the calibration curves linking Hipparcos/Tycho Hp-V_T2 with theCousins V - I index. In total, 321 carbon stars and 4464 M- and S-typestars have new V - I indices. The standard error of the mean V - I isabout 0.1 mag or better down to Hp~9 although it deteriorates rapidly atfainter magnitudes. These V - I indices can be used to verify thepublished Hipparcos V - I color indices. Thus, we have identified ahandful of new cases where, instead of the real target, a random fieldstar has been observed. A considerable fraction of the DMSA/C and DMSA/Vsolutions for red stars appear not to be warranted. Most likely suchspurious solutions may originate from usage of a heavily biased color inthe astrometric processing.Based on observations from the Hipparcos astrometric satellite operatedby the European Space Agency (ESA 1997).}\fnmsep\thanks{Table 7 is onlyavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/397/997
| Reprocessing the Hipparcos data for evolved giant stars II. Absolute magnitudes for the R-type carbon stars
The Hipparcos Intermediate Astrometric Data for carbon stars have beenreprocessed using an algorithm which provides an objective criterion forrejecting anomalous data points and constrains the parallax to bepositive. New parallax solutions have been derived for 317 cool carbonstars, mostly of types R and N. In this paper we discuss the results forthe R stars. The most important result is that the early R stars (i.e.,R0 - R3) have absolute magnitudes and V-K colors locating them among redclump giants in the Hertzsprung-Russell diagram. The average absolutemagnitude MK for early R-type stars (with V - K < 4) hasbeen derived from a Monte-Carlo simulation implicitly incorporating allpossible biases. It appears that the simulated magnitude distributionfor a population with a true Gaussian distribution of mean MK= -2.0 and intrinsic standard deviation 1.0 mag provides a satisfactorymatch to the observed distribution. These values are consistent with theaverage absolute magnitude MK = -1.6 for clump red giants inthe solar neighborhood (Alves 2000). Further, early R-type stars arenon-variable, and their infrared photometric properties show that theyare not undergoing mass loss, properties similar to those of the redclump giants. Stars with subtypes R4 - R9 tend to be cooler and havesimilar luminosity to the N-type carbon stars, as confirmed by theirposition in the (J-H, H-K) color-color diagram. The sample of earlyR-type stars selected from the Hipparcos Catalogue appears to beapproximately complete to magnitude K0 ~ 7, translating intoa completeness distance of 600 pc if all R stars had MK= -2(400 pc if MK= -1). With about 30 early R-type stars in thatvolume, they comprise about 0.04% (0.14% for MK= -1) of thered clump stars in the solar neighborhood. Identification with the redclump locates these stars at the helium core burning stage of stellarevolution, while the N stars are on the asymptotic giant branch, wherehelium shell burning occurs. The present analysis suggests that for asmall fraction of the helium core burning stars (far lower than thefraction of helium shell-burning stars), carbon produced in the interioris mixed to the atmosphere in sufficient quantities to form a carbonstar. Based on observations from the Hipparcos astrometric satelliteoperated by the European Space Agency (ESA 1997).
| General Catalog of Galactic Carbon Stars by C. B. Stephenson. Third Edition
The catalog is an updated and revised version of Stephenson's Catalogueof Galactic Cool Carbon Stars (2nd edition). It includes 6891 entries.For each star the following information is given: equatorial (2000.0)and galactic coordinates, blue, visual and infrared magnitudes, spectralclassification, references, designations in the most significantcatalogs and coordinate precision classes. The main catalog issupplemented by remarks containing information for which there was noplace in entries of the main part, as well as some occasional notesabout the peculiarities of specific stars.
| A general catalogue of cool carbon stars
Not Available
| A general catalogue of cool carbon stars
Not Available
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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | זאב |
| התרוממות ימנית: | 15h28m27.93s |
| סירוב: | -43°59'41.4" |
| גודל גלוי: | 11.711 |
| תנועה נכונה: | -5.2 |
| תנועה נכונה: | -5.2 |
| B-T magnitude: | 13.329 |
| V-T magnitude: | 11.845 |
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