HD 181720 is star with an orbiting substellar companion in the southern constellation of Sagittarius. It is located at a distance of 196 light years from the Sun based on parallax measurements,[2] but is drifting closer with a radial velocity of −45.4 km/s.[4] The star has an absolute magnitude of 4.10,[3] but at that distance it has an apparent visual magnitude of 7.84,[3] which is too faint to be seen with the naked eye. It shows a high proper motion, traversing the celestial sphere at an angular rate of 0.444 arcsec yr−1.[7]
The spectrum of HD 181720 presents as an ordinary G-type main-sequence star with a stellar classification of G1V.[3] It is an older star with an estimated age of roughly 12 billion years[5] and a minimal level of magnetic activity in its chromosphere.[3] The star has 87% of the mass of the Sun but the radius is now 42% larger than the Sun's.[5] Its metallicity content, as measured by the abundance of iron, is three-tenths as much as in the Sun. HD 181720 is radiating more than double the luminosity of the Sun from its photosphere at an effective temperature of 5,781 K.[3]
The star HD 181720 is named Sika. The name was selected in the NameExoWorlds campaign by Ghana, during the 100th anniversary of the IAU. Sika means gold in the Ewe language.[8][9]
^ abcdefCite error: The named reference Anderson_Francis_2012 was invoked but never defined (see the help page).
^ abcdeCite error: The named reference GaiaDR3 was invoked but never defined (see the help page).
^ abcdefghijklCite error: The named reference santos2010 was invoked but never defined (see the help page).
^ abCite error: The named reference Soubiran_et_al_2018 was invoked but never defined (see the help page).
^ abcdefgCite error: The named reference Bonfanti_et_al_2016 was invoked but never defined (see the help page).
^Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
^Cite error: The named reference Luyten1995 was invoked but never defined (see the help page).
^Cite error: The named reference exoworld was invoked but never defined (see the help page).
^Cite error: The named reference iau was invoked but never defined (see the help page).
HD181720 is star with an orbiting substellar companion in the southern constellation of Sagittarius. It is located at a distance of 196 light years from...
HD181720 b is an extrasolar planet which orbits the G-type main sequence star HD181720, located approximately 190 light years away in the constellation...
Planets XXI. Three New Giant Planets Orbiting the Metal-poor Stars HD 5388, HD181720, and HD 190984". Astronomy and Astrophysics. 512 (A47): A47. arXiv:0912...
(three known cases are HD 22781, HD 111232, and HD181720). A telescope or strong binoculars are needed to view the primary. HD 114762 had been used by...
Planets XXI. Three New Giant Planets Orbiting the Metal-poor Stars HD 5388, HD181720, and HD 190984". Astronomy and Astrophysics. 512 (A47): A47. arXiv:0912...
discoveries from HARPS HARPS spectrograph HARPS spectrograph detail Animation of HD 10180 with its seven planets Similar instruments: HARPS-N is a copy of this...
HD 167665 is a yellow-white hued star with a brown dwarf companion in the southern constellation of Sagittarius. With an apparent visual magnitude of 6...
HD 165185 is the Henry Draper Catalogue designation for a star in the southern zodiac constellation of Sagittarius. It has an apparent visual magnitude...
Exoplanets HATS-36b HD 164604 b HD181720 b K2-2016-BLG-0005Lb KMT-2022-BLG-0440L b MOA-2007-BLG-192Lb MOA-2007-BLG-400Lb MOA-2009-BLG-387Lb MOA-2010-BLG-477Lb...
Exoplanets HATS-36b HD 164604 b HD181720 b K2-2016-BLG-0005Lb KMT-2022-BLG-0440L b MOA-2007-BLG-192Lb MOA-2007-BLG-400Lb MOA-2009-BLG-387Lb MOA-2010-BLG-477Lb...
Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 2, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts...
most massive exoplanet candidate is HD 217786 b, which masses 12.98 MJ; the least massive confirmed planet is HD 10180 b, which masses 0.004 MJ or 3.1...
M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts...
M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts...
Exoplanets HATS-36b HD 164604 b HD181720 b K2-2016-BLG-0005Lb KMT-2022-BLG-0440L b MOA-2007-BLG-192Lb MOA-2007-BLG-400Lb MOA-2009-BLG-387Lb MOA-2010-BLG-477Lb...
In 2023, the inclination and true mass of HD 190984 b were determined via astrometry. HD 5388 HD181720 List of extrasolar planets Vallenari, A.; et al...
Exoplanets HATS-36b HD 164604 b HD181720 b K2-2016-BLG-0005Lb KMT-2022-BLG-0440L b MOA-2007-BLG-192Lb MOA-2007-BLG-400Lb MOA-2009-BLG-387Lb MOA-2010-BLG-477Lb...
M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts...
M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts...
cases are HD 111232 and HD181720. In 2012, a radial velocity data review indicated there are no additional giant planets in the system. "HD 22781". SIMBAD...
Exoplanets HATS-36b HD 164604 b HD181720 b K2-2016-BLG-0005Lb KMT-2022-BLG-0440L b MOA-2007-BLG-192Lb MOA-2007-BLG-400Lb MOA-2009-BLG-387Lb MOA-2010-BLG-477Lb...
Exoplanets HATS-36b HD 164604 b HD181720 b K2-2016-BLG-0005Lb KMT-2022-BLG-0440L b MOA-2007-BLG-192Lb MOA-2007-BLG-400Lb MOA-2009-BLG-387Lb MOA-2010-BLG-477Lb...
HD 182681 (186 G. Sagittarii) is a single, blue-hued star in the zodiac constellation of Sagittarius. It has an apparent visual magnitude of +5.64, which...
Exoplanets HATS-36b HD 164604 b HD181720 b K2-2016-BLG-0005Lb KMT-2022-BLG-0440L b MOA-2007-BLG-192Lb MOA-2007-BLG-400Lb MOA-2009-BLG-387Lb MOA-2010-BLG-477Lb...
Exoplanets HATS-36b HD 164604 b HD181720 b K2-2016-BLG-0005Lb KMT-2022-BLG-0440L b MOA-2007-BLG-192Lb MOA-2007-BLG-400Lb MOA-2009-BLG-387Lb MOA-2010-BLG-477Lb...