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Spectral Classification and Effective Temperatures of L and T Dwarfs Based on Near-Infrared Spectra
We have obtained near-infrared spectra of L dwarfs, L/T transitionobjects, and T dwarfs using the Subaru telescope. The resulting spectraare examined in detail to study their dependence on spectral types. Onequestion is where the methane feature appears: we suggest that itappears at L8 and marginally at L6.5. The water bands at 1.1 and 1.4μm do not necessarily show steady increase toward later L types butmay show inversion at late L types. This does not necessarily imply thatthe spectral types do not represent a temperature sequence, but rathercan be interpreted as the increasing water abundance being offset by theheavier dust extinction in the later L types. We confirm that the FeH0.99 μm bands appear not only in the late L dwarfs but also in theearly T dwarfs. We suggest that FeH could be dredged up by the surfaceconvective zone induced by the steep temperature gradient as a result ofthe large opacity of the dust cloud itself, and replenished constantlyby convection.We have obtained bolometric luminosities of the objectswith known parallaxes in our sample, first by integrating the spectrabetween 0.87 and 2.5 μm, and second by the K-band bolometriccorrection. Apart from an L3 dwarf, the bolometric luminosities obtainedby both methods agree well, and this implies that the K-band bolometriccorrection, which is obtained using the unified cloudy models, can beapplied to obtain the bolometric luminosities and effective temperaturesof the L and T dwarfs with known parallaxes from the literature. Therelation between the effective temperature and spectral type derivedfrom the K-band bolometric correction shows monotonic behaviorthroughout the L-T sequence.Based on the data collected at the Subaru Telescope, which is operatedby the National Astronomical Observatory of Japan.
| Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
| A second list of wide visual binaries
Not Available
| A second list of wide visual binaries
Not Available
| Photographic measures of double stars. II
Measures are presented for 302 double stars photographed on 657 plateswith the 36-in. Lick refractor in the period between 1945 and 1962. Thedata provided include the observing epochs, the rectangular coordinatesof the secondary components with reference to the respective primaries,the mean errors of a single measurement, the computed mean errors, thedouble-star separations, and the position angles both for the observingepoch and reduced to the equator of 2000. An additional 561 unmeasuredplates of acceptable quality obtained between 1948 and 1960 are listed.
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Osservazione e dati astrometrici
| Costellazione: | Corona Boreale |
| Ascensione retta: | 15h20m13.27s |
| Declinazione: | +30°41'44.2" |
| Magnitudine apparente: | 9.865 |
| Moto proprio RA: | -13.9 |
| Moto proprio Dec: | -12.5 |
| B-T magnitude: | 10.384 |
| V-T magnitude: | 9.908 |
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