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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.
| Period-Luminosity-Colour distribution and classification of Galactic oxygen-rich LPVs. I. Luminosity calibrations
The absolute K magnitudes and kinematic parameters of about 350oxygen-rich Long-Period Variable stars are calibrated, by means of anup-to-date maximum-likelihood method, using Hipparcos parallaxes andproper motions together with radial velocities and, as additional data,periods and V-K colour indices. Four groups, differing by theirkinematics and mean magnitudes, are found. For each of them, we alsoobtain the distributions of magnitude, period and de-reddened colour ofthe base population, as well as de-biased period-luminosity-colourrelations and their two-dimensional projections. The SRa semiregulars donot seem to constitute a separate class of LPVs. The SRb appear tobelong to two populations of different ages. In a PL diagram, theyconstitute two evolutionary sequences towards the Mira stage. The Mirasof the disk appear to pulsate on a lower-order mode. The slopes of theirde-biased PL and PC relations are found to be very different from theones of the Oxygen Miras of the LMC. This suggests that a significantnumber of so-called Miras of the LMC are misclassified. This alsosuggests that the Miras of the LMC do not constitute a homogeneousgroup, but include a significant proportion of metal-deficient stars,suggesting a relatively smooth star formation history. As a consequence,one may not trivially transpose the LMC period-luminosity relation fromone galaxy to the other Based on data from the Hipparcos astrometrysatellite. Appendix B is only available in electronic form at the CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Semiregular variables of types SRa and SRb. New JHKL' M-photometry for 44 stars.
This paper supplements Kerschbaum & Hron (1994, Paper IIa), wherenew JHKL'M observations of 200 Semiregular variables (SRVs) of types SRaand SRb were presented with additional 44 near infrared observations and5 literature data sets. The total sample was defined in Kerschbaum &Hron (1992, Paper I) by means of a certain limit in bolometricmagnitude. From the sample of 350 objects, 303 now have near infrared(NIR) photometry. In total 339 datasets are available because of somemultiple observations. A detailed analysis of the whole dataset will bepresented in a forthcoming paper.
| Oxygen-rich semiregular and irregular variables
All the known oxygen-rich semiregulars and irregulars of spectralclasses K and M with the absolute value of B not greater than 30 deg,Delta(m) not less than 0.5 mag, and, for the semiregulars, periods inthe range of 50 to 400 d are compiled. On the basis of theirdistributions on the sky and their brightnesses in the K band at 2.2microns, it is argued that the semiregulars with a period of 300-400 dappear to belong to the same population as the 'thin disk' Miras in thesame period range and have an exponential scale height from the Galacticplane of about 250 pc. The semiregulars with a period range of 200 to300 d belong to the population of the 'thick disk' Miras with anexponential scale height from the Galactic plane of about 500 pc. On thebasis of the similarities of their space distributions and the presenceof Tc in their atmospheres, and using the pulsational mode calculationsby Ostlie and Cox (1986), it is suggested that the semiregulars with aperiod range of 100-150 d are first and second overtone pulsations ofthe same population of AGB stars as the Miras in their fundamentalpulsational mode with periods longer than 300 d.
| Semiregular variables of types SRa and SRb - Basic properties in the visual and the IRAS-range
The pulsational properties, T(eff)s, mass loss rates, luminosities,scale heights, and volume densities in the Galactic plane are presentedfor samples of optical semiregular variables of types SRa and SRbcorrelated with the IRAS point source catalog. These properties arecompared to the corresponding characteristics of optical Mira variables.It is found that the SRa's are not a distinct class of variables but amixture of 'intrinsic' Miras and SRb's. The O-rich SRb's form a quitehomogeneous group in terms of periods, amplitudes, and temperatures.They consist of a 'blue' group with no indication of circumstellarshells, with P less than 150 d and T(eff) greater than 3200 K, and a'red' group with temperatures and mass loss rates comparable to Mirasbut periods about a factor of two smaller. The C-rich SRVs generallyhave smaller periods and are more abundant than C-rich Miras. Theevolutionary status of the SRVs is discussed.
| Some Variable Stars in the SRS Catalogue
Not Available
| 58th Name-List of Variable Stars
Not Available
| The varibility of M-stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971MNRAS.152..165S&db_key=AST
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Observation and Astrometry data
| Constellation: | Netz |
| Right ascension: | 04h07m19.59s |
| Declination: | -60°26'50.0" |
| Apparent magnitude: | 9.391 |
| Proper motion RA: | -8.6 |
| Proper motion Dec: | 17.6 |
| B-T magnitude: | 11.453 |
| V-T magnitude: | 9.562 |
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