24 Sextantis

Coordinates: Sky map 10h 23m 28s, −00° 54′ 08″
Source: Wikipedia, the free encyclopedia.
24 Sextantis
Observation data
Epoch J2000      Equinox J2000
Constellation Sextans
Right ascension 10h 23m 28.3694s[1]
Declination –00° 54′ 08.0772″[1]
Apparent magnitude (V) 6.61 ± 0.04[2]
Characteristics
Spectral type K0 IV[3]
B−V color index 0.92 ± 0.01[2]
Distance
236 ± 2 ly
(72.2 ± 0.7 pc)
Absolute magnitude (MV)2.17 ± 0.06[2]
Details
Gyr
HIP 50887, SAO 137532[5]
Database references
SIMBADdata

24 Sextantis, often abbreviated as 24 Sex, is the

rural skies
under good seeing conditions.

At the age of 2.8 billion years, it has reached an

A-type main sequence star before using up the hydrogen at its core. It has 54% more mass than the Sun, but the outer envelope has become cooler than the Sun's as it slowly expands into a giant star
.

The star is known to have two giant

extrasolar planets
.

Planetary system

On July 26, 2010 the

California and Carnegie Planet Search team announced the discovery of two planets around 24 Sextantis along with two planets around HD 200964.[6]
The inner planet is twice as massive as Jupiter and takes 453 days to orbit the star in a circular orbit at the average distance of 1.33 AU (199 Gm). The outer planet is 5/6 the mass of Jupiter and takes 883 days to orbit eccentrically around the star at the average distance of 2.08 AU (312 Gm).

The two planets are in a 2:1 resonance, meaning that the outer planet orbits the star once every time when the inner planet orbits the star twice.[6] The planetary system was found to be unstable in 2019.[7]

The 24 Sextantis planetary system[8]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b ≥1.99+0.26
−0.38 MJ 		1.333+0.004
−0.009 		452.8+2.1
−4.5 		0.09+0.14
−0.06 		— —
c ≥0.86+0.35
−0.26 MJ 		2.08+0.05
−0.02 		883+32
−14 		0.29+0.16
−0.09 		— —

See also

References

  1. ^
    doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR
    .
  2. ^
    doi:10.1088/0004-6256/141/1/16
    .
  3. ^
    Bibcode:1999MSS...C05....0H
    .
  4. S2CID 121883397
  5. ^ "24 Sextantis". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-09-17.
  6. ^
    Astronomy Magazine
    . July 29, 2010. Retrieved 2011-01-13.
  7. doi:10.1093/mnras/stz345
    . Retrieved 28 April 2020.
  8. ^ Jean Schneider (2011). "Notes for star 24 Sex". Extrasolar Planets Encyclopaedia. Archived from the original on August 4, 2010. Retrieved 30 September 2011.


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