HD 156668

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HD 156668
Observation data
J2000.0
Constellation Hercules
Right ascension 17h 17m 40.49053s[1]
Declination +29° 13.6′ 38.0243″[1]
Apparent magnitude (V) +8.424[2]
Characteristics
Spectral type K3 V[2]
U−B color index 0.27
B−V color index 1.015[2]
Distance
79.34 ± 0.03 ly
(24.325 ± 0.010 pc)
Absolute magnitude (MV)6.480[2]
Details
Gyr
HIP 84607, SAO 84984, Wolf 646, 2MASS J17174049+2913378[4]
Database references
SIMBADdata

HD 156668 is a

apparent visual magnitude of 8.4[2] it is too faint to be viewed with the naked eye, but it can be seen with even a small telescope.[5] The distance to this object has been determined directly using the parallax technique, yielding a value of about 80 light-years (25 parsecs).[1]

This star has the

K-type star.[6] It is slightly more enriched in iron compared to the Sun and is rotating at a leisurely rate of once every 51.5 days. Although much older than the Sun, this star is only middle-aged at about 8.6 billion years.[2]

The HD 156668 exhibits a stellar activity cycle with a period about 10 years.[7]

Observations

From 1911 to 1915, Photographic Stellar Spectrum surveys[8] have been carried out by Annie Jump Cannon and Edward Charles Pickering. Anna Mary Palmer who was Henry Draper's wife financed the study, it was also her husband who was responsible for the star's designation in the Henry Draper Catalogue with subsequent extension (HD) although it was first designated as BD+29 2979[9] in the original catalogue that was published in 1863 by Friedrich Wilhelm Argelander due to its position and brightness of 324,198 stars between +90° and −2° declination in the span of an 11-year observation. A number of proper motion surveys was published in 1957 where 9,867 stars in the Southern hemisphere where high proper motion was detected.[10] The name BD was taken from a catalogue of the Bonner Durchmusterung (Bonn Survey)[11] where observations are abbreviated as BD. Latter study expansions were carried out by the Cape Photographic Durchmusterung observatory in Córdoba, Argentina and further extensions by Henry Lee Giclas who designated the star as G 181-34 in the Giclas catalogues. From 1990 to 1993, HD 156668 was observed at least twice and was featured at the 6th annual catalog of the Tokyo Photoelectric Meridian Circle (PMC) where it is one of 6649 stars observed.[12]

Planetary system

Main article: HD 156668 b

Andrew Howard announced the discovery of a

Washington D.C. The planet orbits its star in only 4.6 days with a distance approximately 0.05 AU away from the parent star. The researchers used the wobble method where the resulting spectrum showed color shifts which was used to approximate the mass of the astronomical object. The observation revealed data that the exoplanet was at least 4.15 Earth masses.[13] Later observations revealed that the minimum mass is now 3.1 Earth masses.[14]

Another planet,

HD 156668 c, was discovered in 2021, and presence of additional long-period object is suspected.[7]

The HD 156668 planetary system[14][7]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b ≥3.1 ± 0.4 M🜨 0.0211 ± 0.0002 1.26984 ± 0.00007 0.000 — —
c
 		≥0.0991+0.0079
−0.0077 MJ 		1.570±0.017 811.3+5.2
−5.3 		0.089+0.04
−0.061 		— —

References

  1. ^
    S2CID 18759600
  2. ^
    S2CID 15559379
  3. ^
    doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR
    .
  4. ^ "HD 156668". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2010-02-09.
  5. ISBN 0-486-42820-6
  6. Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original
    on March 18, 2012, retrieved 2012-01-16
  7. ^
    S2CID 235186973
  8. Bibcode:1924AnHar..99....1C
    .
  9. ^ "ARICNS ARI Data Base for Nearby Stars". ASTRONOMISCHES RECHEN-INSTITUT HEIDELBERG. Archived from the original on 2012-03-02. Retrieved 2010-02-09.
  10. Bibcode:1957cnes.book.....L. {{cite book}}: |work= ignored (help
    )
  11. ^ "NASA reference publication -- 1297". Bonner Durchmusterung. {{cite web}}: Missing or empty |url= (help)
  12. ^ "HD 156668". Sky Map.org. Retrieved 2010-02-09.
  13. ^ "Second smallest exoplanet found to date discovered at Keck". W.M. Keck Observatory. Archived from the original on 2016-03-10. Retrieved 2010-02-09.
  14. ^
    S2CID 118592734
    .

External links
Retrieved from "https://en.wikipedia.org/w/index.php?title=HD_156668&oldid=1223045738"