Home     Evrende yaþayabilmek için    
Services
    Niçin Edinmelisiniz     En fazla Destek olanlar     Gökyüzü görüntüsü     Koleksiyon     Forum     Blog New!     SSS     Giriþ  
→ Adopt this star  

HD 157559


Ýçindekiler

Görüntüler

Resim Yükleyin

DSS Images   Other Images


Ýlgili Makaleler

New periodic variables from the Hipparcos epoch photometry
Two selection statistics are used to extract new candidate periodicvariables from the epoch photometry of the Hipparcos catalogue. Theprimary selection criterion is a signal-to-noise ratio. The dependenceof this statistic on the number of observations is calibrated usingabout 30000 randomly permuted Hipparcos data sets. A significance levelof 0.1 per cent is used to extract a first batch of candidate variables.The second criterion requires that the optimal frequency be unaffectedif the data are de-trended by low-order polynomials. We find 2675 newcandidate periodic variables, of which the majority (2082) are from theHipparcos`unsolved' variables. Potential problems with theinterpretation of the data (e.g. aliasing) are discussed.

The chemical evolution of the solar neighborhood. I - A bias-free reduction technique and data sample
The possible ways of measuring the age-metallicity relation for thegalactic disk in the neighborhood of the sun are discussed. It is shownthat the use of a field star sample chosen on the basis of effectivetemperature introduces a bias which results in a monotonic increase inthe metal abundance of the disk with time. However, if theage-metallicity relation for the disk can be shown to satisfy certaincriteria, the bias introduced in such a sample can be neglected: thegalactic disk apparently satisfies the criteria. It is concluded that asample analyzed through the use of uvby and H(beta) photometry inconjunction with a self-consistent set of theoretical isochronesprovides the least biased, most accurate estimate of the age-metallicityrelation for the disk.

Yeni bir Makale Öner


Ýlgili Baðlantýlar

  • - Baðlantý Bulunamadý -
Yeni Bir Baðlantý Öner


sonraki gruplarýn üyesi:


Gözlemler ve gökölçümü verileri

Takýmyýldýz:Sunak
Sað Açýklýk:17h27m19.03s
Yükselim:-57°06'15.5"
Görünürdeki Parlaklýk:8.308
Uzaklýk:416.667 parsek
özdevim Sað Açýklýk:-9.9
özdevim Yükselim:-26.1
B-T magnitude:8.742
V-T magnitude:8.344

Kataloglar ve belirtme:
Özgün isimleri
HD 1989HD 157559
TYCHO-2 2000TYC 8736-199-1
USNO-A2.0USNO-A2 0300-31659175
HIPHIP 85421

→ VizieR 'den daha fazla katalog ve tanýmlama isteyin