HD 17156
HD 17156, named Nushagak by the IAU, is a yellow subgiant star approximately 255 light-years away in the constellation of Cassiopeia. The apparent magnitude is 8.17, which means it is not visible to the naked eye but can be seen with good binoculars. A search for a binary companion star using adaptive optics at the MMT Observatory was negative.

The star is more massive and larger than our Sun while Its absolute magnitude of 3.70 and spectral type of G0, show that it is both hotter and more luminous. Based on asteroseismic density constraints and stellar isochrones, it was found that the age is 3.37 billion years making it about two thirds as old as the sun. Spectral observations show that the star is metal-rich.

An extrasolar planet, HD 17156 b, was discovered with the radial velocity method in 2007, and subsequently was observed to transit the star. At the time it was the transiting planet with the longest period.
Q6867
IAU
ORG
Q6227
yellow subgiant
Concept
Q523
star
Concept
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light-year
Concept
Q8928
constellation
Concept
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Cassiopeia
CEL
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apparent magnitude
Concept
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naked eye
Concept
Q102626
binoculars
Concept
Q506922
adaptive optics
Concept
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MMT Observatory
MISC
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Sun
CEL
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absolute magnitude
Concept
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spectral type
Concept
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luminous
Concept
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asteroseismic
Concept
Q217030
metal-rich
Concept
Q44559
extrasolar planet
Concept
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HD 17156 b
Concept
Q6888
transit
Concept
Q1327736
HD 17156
CEL
2007-01-01T00:00:00Z^^http://www.w3.org/2001/XMLSchema#dateTime
2007
DATE
+8.17^^http://www.w3.org/2001/XMLSchema#decimal
8.17
NUMBER
+3.70^^http://www.w3.org/2001/XMLSchema#decimal
3.70
NUMBER
0^^http://www.w3.org/2001/XMLSchema#decimal
0
NUMBER
+3.37^^http://www.w3.org/2001/XMLSchema#decimal
3.37
NUMBER
instance of
constellation
parent astronomical body
instance of
instance of