Home     Per cominciare     Sopravvivere Nell'Universo    
Inhabited Sky
    News@Sky     Astro Foto     La collezione     Forum     Blog New!     FAQ     Stampa     Login  

HD 128985


Contenuti

Immagini

Carica la tua immagine

DSS Images   Other Images


Articoli relazionati

Metallicities and activities of southern stars
Aims. We present the results from high-resolution spectroscopicmeasurements to determine metallicities and activities of bright starsin the southern hemisphere. Methods: We measured the iron abundances([Fe/H]'s) and chromospheric emission indices (log h{R}'{HK})of 353 solar-type stars with V = 7.5-9.5. [Fe/H] abundances aredetermined using a custom χ2 fitting procedure within alarge grid of Kurucz model atmospheres. The chromospheric activitieswere determined by measuring the amount of emission in the cores of thestrong Caii HK lines. Results: Our comparison of the metallicity sampleto other [Fe/H] determinations was found to agree at the ±0.05dex level for spectroscopic values and at the ±0.1 dex level forphotometric values. The distribution of chromospheric activities isdescribed by a bimodal distribution, agreeing with the conclusions fromother works. Also an analysis of Maunder minimum status was attempted,and it was found that 6 ± 4 stars in the sample could be in aMaunder minimum phase of their evolution and hence the Sun should onlyspend a few per cent of its main sequence lifetime in Maunder minimum.Based on observations made with the ESO telescopes at the La SillaParanal observatory under programme ID's 076.C-0578(B) and077.C-0192(A). Table 4 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/485/571

Improved Astrometry and Photometry for the Luyten Catalog. II. Faint Stars and the Revised Catalog
We complete construction of a catalog containing improved astrometry andnew optical/infrared photometry for the vast majority of NLTT starslying in the overlap of regions covered by POSS I and by the secondincremental Two Micron All Sky Survey (2MASS) release, approximately 44%of the sky. The epoch 2000 positions are typically accurate to 130 mas,the proper motions to 5.5 mas yr-1, and the V-J colors to0.25 mag. Relative proper motions of binary components are measured to 3mas yr-1. The false-identification rate is ~1% for11<~V<~18 and substantially less at brighter magnitudes. Theseimprovements permit the construction of a reduced proper-motion diagramthat, for the first time, allows one to classify NLTT stars intomain-sequence (MS) stars, subdwarfs (SDs), and white dwarfs (WDs). We inturn use this diagram to analyze the properties of both our catalog andthe NLTT catalog on which it is based. In sharp contrast to popularbelief, we find that NLTT incompleteness in the plane is almostcompletely concentrated in MS stars, and that SDs and WDs are detectedalmost uniformly over the sky δ>-33deg. Our catalogwill therefore provide a powerful tool to probe these populationsstatistically, as well as to reliably identify individual SDs and WDs.

Variable Stars in the Pleiades Cluster
Not Available

Sottometti un nuovo articolo


Link relazionati

  • - Nessun link trovato -
Sottometti un nuovo link


Membro dei seguenti gruppi:


Osservazione e dati astrometrici

Costellazione:Vergine
Ascensione retta:14h40m12.87s
Declinazione:-07°30'53.0"
Magnitudine apparente:9.176
Distanza:39.841 parsec
Moto proprio RA:-187.5
Moto proprio Dec:155
B-T magnitude:10.24
V-T magnitude:9.264

Cataloghi e designazioni:
Nomi esatti   (Edit)
HD 1989HD 128985
TYCHO-2 2000TYC 5564-822-1
USNO-A2.0USNO-A2 0750-08580611
HIPHIP 71720

→ Richiesta di ulteriori cataloghi da VizieR