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Effective temperature scale and bolometric corrections from 2MASS photometry
We present a method to determine effective temperatures, angularsemi-diameters and bolometric corrections for population I and II FGKtype stars based on V and 2MASS IR photometry. Accurate calibration isaccomplished by using a sample of solar analogues, whose averagetemperature is assumed to be equal to the solar effective temperature of5777 K. By taking into account all possible sources of error we estimateassociated uncertainties to better than 1% in effective temperature andin the range 1.0-2.5% in angular semi-diameter for unreddened stars.Comparison of our new temperatures with other determinations extractedfrom the literature indicates, in general, remarkably good agreement.These results suggest that the effective temperaure scale of FGK starsis currently established with an accuracy better than 0.5%-1%. Theapplication of the method to a sample of 10 999 dwarfs in the Hipparcoscatalogue allows us to define temperature and bolometric correction (Kband) calibrations as a function of (V-K), [m/H] and log g. Bolometriccorrections in the V and K bands as a function of T_eff, [m/H] and log gare also given. We provide effective temperatures, angularsemi-diameters, radii and bolometric corrections in the V and K bandsfor the 10 999 FGK stars in our sample with the correspondinguncertainties.
| Nature of the Strongly Lensed Submillimeter Galaxy SMM J14011+0252
We have carried out near-infrared JHK spectroscopy of thegravitationally lensed submillimeter galaxy SMM J14011+0252 at z=2.565,using the OH-airglow suppressor and the Cooled Infrared Camera andSpectrograph for OHS on the Subaru Telescope. This object consists oftwo optical components, J1 and J2, which are lensed by the cluster Abell1835. J1 suffers additional strong lensing by a foreground galaxy atz=0.25 in the cluster. The rest-frame optical Hα, Hβ, and [OII] λ3727 lines are detected in both J1 and J2, and [N II]λλ6548, 6583 lines are also detected in J1. A diagnosis ofemission-line ratios shows that the excitation source of J1 is stellarin origin, consistent with previous X-ray observations. The continua ofJ1 and J2 show breaks at rest-frame 4000 Å, indicating arelatively young age. Combined with optical photometry, we have carriedout model-spectrum fitting of J2 and find that it is a very young (~50Myr) galaxy of rather small mass (~108 Msolar)that suffers some amount of dust extinction. A new gravitational lensingmodel is constructed to assess both the magnification factor andcontamination from the lensing galaxy of the component J1, using aHubble Space Telescope F702W image. We have found that J1 suffers stronglensing with magnification of ~30, and its stellar mass is estimated tobe <~109 Msolar. These results suggest that SMMJ14011+0252 is a major merger system at high redshift that undergoesintense star formation but is not a formation site of a giant ellipticalgalaxy. Still having plenty of gas, it will transform most of the gasinto stars and will evolve into a galaxy of <~1010Msolar. Therefore, this system is possibly an ancestor of apresent-day, less massive galaxy such as a midsized elliptical galaxy ora spiral galaxy.Based on data collected at Subaru Telescope, which is operated by theNational Astronomical Observatory of Japan.
| Radial velocities. Measurements of 2800 B2-F5 stars for HIPPARCOS
Radial velocities have been determined for a sample of 2930 B2-F5 stars,95% observed by the Hipparcos satellite in the north hemisphere and 80%without reliable radial velocity up to now. Observations were obtainedat the Observatoire de Haute Provence with a dispersion of 80Ä,mm(-1) with the aim of studying stellar and galactic dynamics.Radial velocities have been measured by correlation with templates ofthe same spectral class. The mean obtained precision is 3.0 km s(-1)with three observations. A new MK spectral classification is estimatedfor all stars. Based on observations made at the Haute ProvenceObservatory, France and on data from The Hipparcos Catalogue, ESA.Tables 4, 5 and 6 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr or viahttp://cdsweb.u-strasbg.fr/Abstract.htm
| Common proper motion stars in the AGK 3
A search was made of common-proper-motion (CPM) systems among AGK 3stars. The selection of physical systems was based upon the ratiobetween the angular separation (rho) and the proper motion (mu); the CPMstars found are presented in two tables. Table I lists systems withrho/mu less than 1000 years. It contains 326 entries, and the proportionof optical pairs is estimated to be 1 percent. Table II lists systemswith rho/mu in the range 1000 to 3500 years; it contains 113 systems,but only 60 percent of them are physical. Nevertheless, these systemsoften have separations larger than 10,000 AU and are the mostinteresting for the study of the tail of the distribution function ofthe semimajor axes.
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Osservazione e dati astrometrici
| Costellazione: | Vergine |
| Ascensione retta: | 13h53m29.82s |
| Declinazione: | +03°37'36.8" |
| Magnitudine apparente: | 8.656 |
| Distanza: | 121.359 parsec |
| Moto proprio RA: | -44.5 |
| Moto proprio Dec: | 0.1 |
| B-T magnitude: | 9.059 |
| V-T magnitude: | 8.69 |
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