8 Ursae Minoris

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8 Ursae Minoris / Baekdu
Observation data
Epoch J2000      Equinox
Constellation Ursa Minor
Right ascension 14h 56m 48.35230s[1]
Declination +74° 54′ 03.3212″[1]
Apparent magnitude (V) 6.835[2]
Characteristics
Evolutionary stage Red clump[3]
Spectral type G8III[4]
Distance
532 ± 1 ly
(163.2 ± 0.4 pc)
Absolute magnitude (MV)+0.82[5]
Details
Myr
Gaia DR3 1700658653802527104[7]
Database references
SIMBADdata

8 Ursae Minoris is a 7th-magnitude red clump star in Ursa Minor. The star is unusually rich in lithium, with an abundance of A = 2.0±0.2 dex.[8][9][3]

In the 2019 NameExoWorlds competition, the star was assigned to contestants in South Korea. It was named Baekdu after Paektu Mountain, the tallest mountain in North Korea.[10][11]

Planetary system

One exoplanet was discovered in 2015 by the

host star — it should have been consumed during a previous expansion to 0.7 AU.[13][14] It is officially named Halla after Hallasan, the tallest mountain in South Korea.[10][14] There is also a stellar activity cycle of 65 days, and possibly a second companion orbiting at a distance of at least 5 AU.[3]

The 8 Ursae Minoris planetary system
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b / Halla ≥ 1.65±0.06 MJ 0.462±0.006 93.31±0.06 0.062±0.18 — —

A 2023 study suggests that 8 Ursae Minoris was initially a

stellar merger. 8 Ursae Minoris is now in the red clump stage, and the planet will eventually be engulfed once it reaches the asymptotic giant branch.[3]

References

  1. ^
    S2CID 244398875
    . Gaia DR3 record for this source at VizieR.
  2. ISSN 0004-6361
    .
  3. ^
    S2CID 259275140
    .
  4. doi:10.1086/423803
    .
  5. S2CID 119257644
    .
  6. S2CID 119096144
    .
  7. ^ "* 8 UMi". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2023-06-29.
  8. S2CID 118383042
    .
  9. S2CID 253098085
    .
  10. ^ a b "Approved names". NameExoworlds. Retrieved 2020-01-02.
  11. ^ "International Astronomical Union | IAU". www.iau.org. Retrieved 2020-01-02.
  12. S2CID 119294400
    .
  13. ^ Timmer, John (28 June 2023). "Planet that shouldn't exist found". Ars Technica. Retrieved 29 June 2023.
  14. ^ a b Strickland, Ashley (2023-06-28). "Scientists spot a planet that shouldn't exist". CNN. Retrieved 2023-06-29.
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