Home     To Survive in the Universe    
Services
    Why to Inhabit     Top Contributors     Astro Photo     The Collection     Forum     Blog New!     FAQ     Login  
→ Adopt this star  

HD 157321


Contents

Images

- No Images Found -
Upload your image

DSS Images   Other Images


Related articles

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.

Submit a new article


Related links

  • - No Links Found -
Submit a new link


Member of following groups:


Observation and Astrometry data

Constellation:Βωμός
Right ascension:17h27m19.05s
Declination:-65°00'07.5"
Apparent magnitude:8.024
Distance:181.488 parsecs
Proper motion RA:4
Proper motion Dec:-4.7
B-T magnitude:8.413
V-T magnitude:8.057

Catalogs and designations:
Proper Names
HD 1989HD 157321
TYCHO-2 2000TYC 9061-207-1
USNO-A2.0USNO-A2 0225-27655205
HIPHIP 85420

→ Request more catalogs and designations from VizieR