HD 197027

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HD 197027
HIP 102152.jpg
HIP 102152
Credit: ESO/Digitized Sky Survey 2
Observation data
Epoch J2000      Equinox J2000
Constellation Capricornus
Right ascension 20:41:45.632h[1]
Declination −27:12:57.414°[1]
Apparent magnitude (V) 9.18
Spectral type G3V[1]
B−V color index +0.65[1]
Radial velocity (Rv) -44.3[1] km/s
Proper motion (μ) RA: +172.91[1] mas/yr
Dec.: -15.41[1] mas/yr
Parallax (π) 12.84 ± 0.97[1] mas
Distance 250 ± 20 ly
(78 ± 6 pc)
Absolute magnitude (MV) 4.72
Mass 0.97[2] M
Surface gravity (log g) 4.35 ± 0.023[2] cgs
Temperature 5,723 ± 547[2] K
Metallicity [Fe/H] -0.013
 ± 0.004[2] dex
Age 8.2[2] Gyr
Other designations
HIP 102152

PPM 271498

SAO 189585.[1]
Database references

HD 197027 (HIP 102152) is a star in the constellation Capricornus that is located about 250 light years from the Sun.

The measured properties of this star are very similar to those of the Sun, making it a candidate older solar twin.[3] The abundances of 21 elements overall are more similar to the Sun than any other known solar twin. Additionally, the effective temperature, surface gravity, and microturbulence are nearly identical to the Sun's. However, it is significantly older than the Sun, being approximately 3.6 billion years older than the Sun, at 8.2 Billion years old. The fact that the abundances are so similar to the Sun's suggests that it is a potential candidate for hosting terrestrial type planets.


The age of HD 197027, here annotated as HIP 102152, shown relative to the Sun, the younger solar twin 18 Scorpii and the formation of the Milky Way

Sun comparison[edit]

This chart compares the sun to HD 197027/HIP 102152.

Identifier J2000 Coordinates[1] Distance[1]
Right ascension Declination
Sun 0.00 G2V 5,778 +0.00 4.6 [4]
HD 197027 [5] 20h 41m 54.6s –27° 12′ 57″ 250 G3V 5,723 −0.013 8.2 [6]

An exact solar twin would be a G2V star with a 5,778K temperature, be 4.6 billion years old, with the correct metallicity and a 0.1% solar luminosity variation.[7] Stars with an age of 4.6 billion years are at the most stable state. Proper metallicity and size are also very important to low luminosity variation.[8][9][10]


  1. ^ a b c d e f g h i j k l "HD 197027". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2013-09-07. 
  2. ^ a b c d e Talawanda R. Monroe; et al. (Aug 2013). "High Precision Abundances of the Old Solar Twin HIP 102152: Insights on Li Depletion from the Oldest Sun". Astrophysical Journal Letters. 774 (2): L32. arXiv:1308.5744Freely accessible. Bibcode:2013ApJ...774L..32M. doi:10.1088/2041-8205/774/2/l32. 
  3. ^ ESO, The life cycle of a Sun-like star (annotated), from European Southern Observatory, 28 August 2013
  4. ^ Williams, D.R. (2004). "Sun Fact Sheet". NASA. Retrieved 2009-06-23. 
  5. ^ HIP 102152 at SIMBAD - Ids - Bibliography - Image.
  6. ^ Monroe, T. R.;; et al. (2013). "High Precision Abundances of the Old Solar Twin HIP 102152: Insights on Li Depletion from the Oldest Sun". The Astrophysical Journal Letters. 774 (2): 22. arXiv:1308.5744Freely accessible. Bibcode:2013ApJ...774L..32M. doi:10.1088/2041-8205/774/2/L32. 
  7. ^ NASA, Science News, Solar Variability and Terrestrial Climate, Jan. 8, 2013
  8. ^ University of Nebraska-Lincoln astronomy education group, Stellar Luminosity Calculator
  9. ^ National Center for Atmospheric Research, The Effects of Solar Variability on Earth's Climate, 2012 Report
  10. ^ Most of Earth’s twins aren’t identical, or even close!, by Ethan on June 5, 2013

External links[edit]