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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
| New periodic variables from the Hipparcos epoch photometry
Two selection statistics are used to extract new candidate periodicvariables from the epoch photometry of the Hipparcos catalogue. Theprimary selection criterion is a signal-to-noise ratio. The dependenceof this statistic on the number of observations is calibrated usingabout 30000 randomly permuted Hipparcos data sets. A significance levelof 0.1 per cent is used to extract a first batch of candidate variables.The second criterion requires that the optimal frequency be unaffectedif the data are de-trended by low-order polynomials. We find 2675 newcandidate periodic variables, of which the majority (2082) are from theHipparcos`unsolved' variables. Potential problems with theinterpretation of the data (e.g. aliasing) are discussed.
| Stars with the Largest Hipparcos Photometric Amplitudes
A list of the 2027 stars that have the largest photometric amplitudes inHipparcos Photometry shows that most variable stars are all Miras. Thepercentage of variable types change as a function of amplitude. Thiscompilation should also be of value to photometrists looking forrelatively unstudied, but large amplitude stars.
| In Search of the Southern Cross
This accounting of a month-long journey through New Zealand, Fiji, andAustralia describes the author's observations of the wondrous nightskies at these locations, meeting with southern amateurs, and a visit tofamous Siding Springs Observatory. The results of a limited study ofthree unconfirmed Fleming variables are presented. No variation wasnoted in 21 visual observations of NSV 840 (constant at visual magnitude7.9), NSV 1214 (constant at visual magnitude 8.3), and NSV 3379(constant at visual magnitude 7.1). Comments are presented on othersouthern variable stars observed, including the recently-publicized etaCarinae. Astrophotos obtained with the Anglo-Australian-Telescopeillustrate some of the most impressive deep sky objects in the southernheavens.
| The 74th Special Name-list of Variable Stars
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
| Stellar radii of M giants
We determine the stellar radii of the M giant stars in the Hipparcoscatalogue that have a parallax measured to better than 20% accuracy.This is done with the help of a relation between a visual surfacebrightness parameter and the Cousins (V - I) colour index, which wecalibrate with M giants with published angular diameters.The radii of(non-Mira) M giants increase from a median value of 50 R_Sun at spectraltype M0 III to 170 R_Sun at M7/8 III. Typical intermediate giant radiiare 65 R_Sun for M1/M2, 90 R_Sun for M3, 100 R_Sun for M4, 120 R_Sun forM5 and 150 R_Sun for M6. There is a large intrinsic spread for a givenspectral type. This variance in stellar radius increases with latertypes but in relative terms, it remains constant.We determineluminosities and, from evolutionary tracks, stellar masses for oursample stars. The M giants in the solar neighbourhood have masses in therange 0.8-4 M_Sun. For a given spectral type, there is a close relationbetween stellar radius and stellar mass. We also find a linear relationbetween the mass and radius of non-variable M giants. With increasingamplitude of variability we have larger stellar radii for a given mass.
| Un-Named Fleming Variables
Amoung nearly 300 variable stars discoverd by Williamina P. Fleming orunder her direction, there are only fourteen that have not beensufficiently observed to have been assigned permanent designations inthe General Catalogue of Variable Stars. From the available data, theyappear to merit further investigation.
| Classification and Identification of IRAS Sources with Low-Resolution Spectra
IRAS low-resolution spectra were extracted for 11,224 IRAS sources.These spectra were classified into astrophysical classes, based on thepresence of emission and absorption features and on the shape of thecontinuum. Counterparts of these IRAS sources in existing optical andinfrared catalogs are identified, and their optical spectral types arelisted if they are known. The correlations between thephotospheric/optical and circumstellar/infrared classification arediscussed.
| Detection of 51 new 86 GHz SiO, V = 1, J = 2-1 masers associated with IRAS point sources
This paper reports the results of a search for southern stellar SiO, v =1, J = 2-1 masers in a survey of IRAS point sources. Out of the 116observed southern sources, 51 identified as new SiO, v = 1, J = 2-1masers, on the basis of their position in IRAS color-color plot. Ofthese, 42 masers have stellar identifications in IPSC, two arepreviously known non-IRAS IR objects, and six have no identification inIPSC.
| IRAS catalogues and atlases - Atlas of low-resolution spectra
Plots of all 5425 spectra in the IRAS catalogue of low-resolutionspectra are presented. The catalogue contains the average spectra ofmost IRAS poiont sources with 12 micron flux densities above 10 Jy.
| The brightest high-latitude 12-micron IRAS sources
The Infrared Astronomical Satellite (IRAS) Point Source catalog wassearched for sources brighter than 28 Jy (0 mag) at 12 microns withabsolute galactic latitude greater than 30 deg excluding the LargeMagellanic Cloud. The search resulted in 269 sources, two of which arethe galaxies NGC 1068 and M82. The remaining 267 sources are identifiedwith, or have infrared color indices consistent with late-type starssome of which show evidence of circumstellar dust shells. Seven sourcesare previously uncataloged stars. K and M stars without circumstellardust shells, M stars with circumstellar dust shells, and carbon starsoccupy well-defined regions of infrared color-color diagrams.
| Bright Southern BV-Stars
Not Available
| Sixty-four new variable stars.
Not Available
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Группы:
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Наблюдательные данные и астрометрия
| Созвездие: | Южная Гидра |
| Прямое восхождение: | 02h27m46.84s |
| Склонение: | -69°31'26.4" |
| Видимая звёздная величина: | 7.282 |
| Расстояние: | 154.799 парсек |
| Собственное движение RA: | -12 |
| Собственное движение Dec: | 31.9 |
| B-T magnitude: | 8.86 |
| V-T magnitude: | 7.413 |
Каталоги и обозначения:
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