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HD 22900


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Evidence of helium abundance differences between young groups of stars
Seven groups of B-type stars - Sco-Cen, NGC 6231, LacOBI,OriOBIb, h + chi Per, CepOBIII, and field stars - wereinvestigated photoelectrically to determine whether helium abundance isuniform in the solar neighborhood and in a region of the spiral arm ofthe Galaxy. Observations were performed using an echelle spectrometer inthe narrow band index of the I (4026) of the He I-4026 line. Amodel-atmosphere analysis of I (4026) and the beta index of the H betaline shows that in the spectral range B O-B 2, the relation between I(4026) and beta is insensitive to differences in the surface gravity butsensitive to differences in the helium to hydrogen ratio. It is foundthat stars in the two groups most distant from the sun - h + chi Per andCepOBIII - have a lower helium abundance than stars in the solarneighborhood.

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Osservazione e dati astrometrici

Costellazione:Eridano
Ascensione retta:03h39m01.50s
Declinazione:-40°37'52.4"
Magnitudine apparente:8.315
Distanza:338.983 parsec
Moto proprio RA:3.6
Moto proprio Dec:8.6
B-T magnitude:9.807
V-T magnitude:8.439

Cataloghi e designazioni:
Nomi esatti   (Edit)
HD 1989HD 22900
TYCHO-2 2000TYC 7572-459-1
USNO-A2.0USNO-A2 0450-01249131
HIPHIP 17028

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