Contents
Images
Upload your image
DSS Images Other Images
Related articles
Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters
The availability of the Hipparcos Catalogue has triggered many kinematicand dynamical studies of the solar neighbourhood. Nevertheless, thosestudies generally lacked the third component of the space velocities,i.e., the radial velocities. This work presents the kinematic analysisof 5952 K and 739 M giants in the solar neighbourhood which includes forthe first time radial velocity data from a large survey performed withthe CORAVEL spectrovelocimeter. It also uses proper motions from theTycho-2 catalogue, which are expected to be more accurate than theHipparcos ones. An important by-product of this study is the observedfraction of only 5.7% of spectroscopic binaries among M giants ascompared to 13.7% for K giants. After excluding the binaries for whichno center-of-mass velocity could be estimated, 5311 K and 719 M giantsremain in the final sample. The UV-plane constructed from these datafor the stars with precise parallaxes (σπ/π≤20%) reveals a rich small-scale structure, with several clumpscorresponding to the Hercules stream, the Sirius moving group, and theHyades and Pleiades superclusters. A maximum-likelihood method, based ona Bayesian approach, has been applied to the data, in order to make fulluse of all the available stars (not only those with precise parallaxes)and to derive the kinematic properties of these subgroups. Isochrones inthe Hertzsprung-Russell diagram reveal a very wide range of ages forstars belonging to these groups. These groups are most probably relatedto the dynamical perturbation by transient spiral waves (as recentlymodelled by De Simone et al. \cite{Simone2004}) rather than to clusterremnants. A possible explanation for the presence of younggroup/clusters in the same area of the UV-plane is that they have beenput there by the spiral wave associated with their formation, while thekinematics of the older stars of our sample has also been disturbed bythe same wave. The emerging picture is thus one of dynamical streamspervading the solar neighbourhood and travelling in the Galaxy withsimilar space velocities. The term dynamical stream is more appropriatethan the traditional term supercluster since it involves stars ofdifferent ages, not born at the same place nor at the same time. Theposition of those streams in the UV-plane is responsible for the vertexdeviation of 16.2o ± 5.6o for the wholesample. Our study suggests that the vertex deviation for youngerpopulations could have the same dynamical origin. The underlyingvelocity ellipsoid, extracted by the maximum-likelihood method afterremoval of the streams, is not centered on the value commonly acceptedfor the radial antisolar motion: it is centered on < U > =-2.78±1.07 km s-1. However, the full data set(including the various streams) does yield the usual value for theradial solar motion, when properly accounting for the biases inherent tothis kind of analysis (namely, < U > = -10.25±0.15 kms-1). This discrepancy clearly raises the essential questionof how to derive the solar motion in the presence of dynamicalperturbations altering the kinematics of the solar neighbourhood: doesthere exist in the solar neighbourhood a subset of stars having no netradial motion which can be used as a reference against which to measurethe solar motion?Based on observations performed at the Swiss 1m-telescope at OHP,France, and on data from the ESA Hipparcos astrometry satellite.Full Table \ref{taba1} 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/cgi-bin/qcat?J/A+A/430/165}
| 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
| 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.
| Hipparcos: The Stars
Not Available
| The 74th Special Name-list of Variable Stars
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
| M giants at high galactic latitudes: an old metal-rich population?
Spectroscopic and photometric observations are presented for a sample of227 late-M giants in the extended solar neighbourhood, catalogued byStephenson using objective prism plates. The kinematics and scaleheightof these stars suggest that they belong to a mixed population, extendingfrom the old thin disc to the thick disc. They show evidence of thedifferential galactic rotation predicted theoretically. Metallicitieshave been determined from a comparison of TiO band strengths andinfrared colours with model atmospheres for late-type stars, and suggesta mean metallicity close to solar.
| Late M stars found in a hemispheric survey
An objective-prism survey of somewhat more than half the sky, being theportion more than 10 deg from the Galactic plane and north ofdeclination -25 deg, has been completed, using the visual-red spectralregion. From this survey 583 late M stars (mostly type M6 or later) notcontained in the third edition of the variable star catalog or itssupplements are listed. Many identifications with the Caltech Two-MicronSurvey are given. The great majority of the stars are likely to begiants. For an assumed visual absolute magnituge of -0.9, the distanceof the stars from the Galactic plane is well represented by anexponential (barometric) distribution with scale height 1800 pc; or 900pc for an assumed absolute magnitude of zero. The sample may well berelated, therefore, to the recently discussed 'thick disk' component ofgalactic structure. Carbon stars appear to be at least twice asnumerous, relative to late M stars, at large Galactic Z as at small Z.Although difficult to quantify, it appears unlikely that large numbersof these late M stars are undiscovered variables of appreciableamplitude.
| The stellar component of the galaxy as seen by the AFGL infrared sky survey
The noise-limited magnitudes for the Air Force Geophysical Laboratory(AFGL) Infrared Sky Survey have been estimated by direct comparison withground-based observations. Using these limiting magnitudes, 'pruned'versions of the AFGL catalog have been generated. Infrared observationsof all the stellar objects seen at 11, 20, or 27 microns and astatistical sample of the stars seen only at 4 microns are reported.Analysis of the observations leads to estimates of the absolute 4 and 10microns magnitudes and space densities for the two clases of objects.The expected results from the Infrared Astronomical Satellite arereexamined.
| Suggested Identifications for Infrared Sources
Not Available
| SiO masers in R Aquarii and other infrared stars
Observations carried out with the Kitt Peak radio telescope haverevealed SiO maser emission from R Aqr and eight other objects from theIRC catalog. Variations in the radial velocity of the R Aqr maser (v =1, J = 2 to 1) may be used to establish the binary nature of this starwithin about 10 years. A measurement of the orbital period wouldindicate whether R Aqr is a close, contact or common envelope system.SiO maser radiation is detectable over a continuous radial velocityrange of about 50 km/sec toward the Kleinmann-Low nebula; the 1(01) to1(10) transition of CH3NCH2 was not observed.
| A survey of infrared stars and planetary nebulae for circumstellar OH emission
The 1000-ft Arecibo antenna was used to survey a total of 76 late-typestars, IRC and CRL infrared sources, and planetary nebulae in the 1612-,1665-, and 1667-MHz lines of the OH molecule. OH was detected for thefirst time in eight objects, most of which are cool, evolved, giantstars. No planetary nebulae were detected nor were any stars previouslyclassified or suggested to be either carbon-rich or S-type, including,for example, CRL 618, IRC+10216, BD 30 deg 3639, Chi Cyg, FG Sge, CRL2688, CRL 3068, NGC 6572, and CRL 3099. High signal-to-noise spectrawere obtained for some known OH maser stars such as NML Tau andIRC+10011.
| 2.2-micron field stars at the North Galactic Pole
The properties of the 2.2-micron field stars seen near the NorthGalactic Pole by the Two Micron Sky Survey and by surveys at highersensitivity are discussed. All the 2.2-micron sources found in thesesurveys can be identified with stars with known spectral types. Thedistribution of the 2.2-micron field stars appears to bewell-understood.
| Characteristics of OH emission from infrared stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972A&A....17..385W&db_key=AST
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
| Constellation: | Grande Ourse |
| Right ascension: | 11h35m30.70s |
| Declination: | +34°52'04.2" |
| Apparent magnitude: | 9.592 |
| Distance: | 245.098 parsecs |
| Proper motion RA: | -15.1 |
| Proper motion Dec: | -10.6 |
| B-T magnitude: | 11.404 |
| V-T magnitude: | 9.742 |
Catalogs and designations:
|
INHABITED SKY
