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A Survey for A Coeval, Comoving Group Associated with HD 141569
We present the results of a search for a young stellar moving groupassociated with the star HD 141569—a nearby, isolated Herbig AeBeprimary member of a 5 ± 3 Myr-old triple star system on theoutskirts of the Sco-Cen complex. Our spectroscopic survey identified apopulation of 21 Li-rich, lsim 30 Myr-old stars within 30° of HD141569 which possess similar proper motions with the star. The spatialdistribution of these Li-rich stars, however, is not suggestive of amoving group associated with the HD 141569 triplet, but rather thissample appears cospatial with Upper Scorpius (US) and Upper CentaurusLupus (UCL). We apply a modified moving cluster parallax method tocompare the kinematics of these youthful stars with those of the US andUCL. Eight new potential members of US and five new potential members ofUCL are identified. A substantial moving group with an identifiablenucleus within 15° (~ 30 pc) of HD 141569 is not found in thissample. Evidently, the HD 141569 system formed ~ 5 Myr ago in relativeisolation, tens of parsecs away from the recent sites of star formationin the Ophiucus-Scorpius-Centaurus region.
| 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.
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Osservazione e dati astrometrici
| Costellazione: | Bilancia |
| Ascensione retta: | 15h26m05.91s |
| Declinazione: | -11°41'55.7" |
| Magnitudine apparente: | 8.456 |
| Distanza: | 96.154 parsec |
| Moto proprio RA: | -15 |
| Moto proprio Dec: | -14.7 |
| B-T magnitude: | 8.935 |
| V-T magnitude: | 8.496 |
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