Kepler-444

Coordinates: Sky map 19h 19m 01.0s, +41° 38′ 05″
Source: Wikipedia, the free encyclopedia.

Kepler-444

Adaptive optics image of the Kepler-444 system from Zhang et al.[1]
Observation data
Epoch J2000      Equinox 2000
Constellation
Lyra[2]
Kepler-444 A
Right ascension 19h 19m 00.5489s[3]
Declination +41° 38′ 04.582″[3]
Apparent magnitude (V) 8.86[4]
Kepler-444 B/C
Right ascension 19h 19m 00.3922s[5]
Declination +41° 38′ 04.013″[5]
Characteristics
Spectral type K0V[6]
Distance
118.1 ± 0.2 ly
(36.22 ± 0.07 pc)
Argument of periastron
(ω)
(secondary)		227.3+6.5
−5.2°
Details
A
Gyr
B
Mass0.307+0.009
−0.008[1] M☉
Surface gravity (log g)5.0±0.2[2] cgs
Temperature3,464±200[2] K
C
Mass0.296±0.008[1] M☉
Surface gravity (log g)~5[2] cgs
Temperature3,500 - 4,000[2] K
TYC 3129-00329-1, 2MASS J19190052+4138043[10]
Kepler-444BC: Gaia DR2 2101486923382009472[11]
Database references
SIMBADdata
B/C

Kepler-444 (or KOI-3158, KIC 6278762, 2MASS J19190052+4138043, BD+41°3306)

K-type main sequence star.[13][14][15][12][16] All of the planets are far too close to their star to harbour life forms.[13]

Discovery

Preliminary results of the planetary system around Kepler-444 were first announced at the second Kepler Science Conference in 2013. At that conference, the star was known as KOI-3158.[17]

Characterization of the host star with asteroseismology was supported in part by the Nonprofit Adopt a Star program operated by White Dwarf Research Corporation, a crowd funded non-profit organization.[15]

History

On 28 January 2015, astronomers using data from NASA's

Earth-sized planets in Kepler-444. Evidential speculations in research show Kepler-444 formed 11.2 billion years ago, when the universe was less than 20 percent of its current age, making it two and a half times older than the Earth
.

Characteristics

The star, Kepler-444, is approximately 11.2 billion years old, whereas the Sun is only 4.6 billion years old. The age is that of Kepler-444 A, an orange main sequence star of spectral type K0.[18] Despite this great age, it is in middle of its main-sequence lifespan, much like the Sun.

The original research on Kepler-444 was published in The Astrophysical Journal on 27 January 2015 under the title "An ancient extrasolar system with five sub-Earth-size planets" by a team of 40 authors.[2]

Stellar system

Diagram showing the change in radial velocity over time caused by the orbiting M dwarf pair.
Radial velocity time series of Kepler 444 showing linear trend in velocities caused by the pair of M-dwarf stars from Weiss et al.[19]

The Kepler-444 system consists of the planet hosting primary and a pair of M-dwarf stars. The M-dwarfs orbit each other at a distance of less than 0.3 AU while the pair orbits the primary in a highly eccentric 324-year orbit. The pair comes within 23.55 AU of the primary potentially truncating the protoplanetary disk from which the planets formed at 8 AU. This would have depleted the availability of solid material to form the observed planets.[1]

Previous stellar orbit solution was ever more extreme, period was shorter (211 years) and eccentricity was much larger (e=0.865), moving periastron to 5 AU, severely reducing the estimated protoplanetary disk size to 1–2 AU and its estimated mass from ~600 to ~4 Earth masses.[7]

Planetary system

All five rocky exoplanets (Kepler-444b; Kepler-444c; Kepler-444d; Kepler-444e; Kepler-444f) are confirmed,[16] smaller than the size of Venus (but bigger than Mercury) and each of the exoplanets completes an orbit around the host star in less than 10 days.[13][12] Thus, the planetary system is very compact, as even the furthest known planet, Kepler-444f, still orbits closer to the star than Mercury is to the Sun.[18] According to NASA, no life as we know it could exist on these hot exoplanets, due to their close orbital distances to the host star.[13] To keep the known planetary system stable, no additional giant planets can be located within 5.5 AU of the parent star.[20]

Moreover, the system is pervaded by high-order resonance chain: period ratios are 4:5, 3:4, 4:5, 4:5. This tight chain is unperturbed and very likely continues farther from Kepler-444A.

The Kepler-444 planetary system[16][21]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b — 0.04178 3.600105+0.000031
−0.000037 		0.16 88° 0.406±0.013 R🜨
c — 0.04881 4.545876±0.000031 0.31 88.2° 0.521±0.017 R🜨
d 0.036+0.065
−0.020 M🜨 		0.06 6.189437+0.000053
−0.000037 		0.18 88.16° 0.54±0.017 R🜨
e 0.034+0.059
−0.019 M🜨 		0.0696 7.743467+0.00006
−0.0001 		0.1 89.13° 0.555+0.018
−0.016 R🜨
f — 0.0811 9.740501+0.000078
−0.000026 		0.29 87.96° 0.767±0.025 R🜨

See also

  • Kepler-80 - most compact 6-planet system discovered so far
  • List of extrasolar planets
  • PSR B1620-26 - an ancient planetary system in Messier 4

References

  1. ^
    doi:10.3847/1538-3881/aca88c
    .
  2. ^
    doi:10.1088/0004-637X/799/2/170
    .
  3. ^
    S2CID 244398875
    . Gaia DR3 record for this source at VizieR.
  4. Bibcode:2002yCat.2237....0D
    .</ref
  5. ^
    S2CID 244398875
    . Gaia DR3 record for this source at VizieR.
  6. doi:10.1086/147437
    .
  7. ^
    doi:10.3847/0004-637X/817/1/80
    .
  8. ^
    S2CID 198229778
    .
  9. doi:10.1088/0004-637X/801/1/3
    .
  10. ^ a b "BD+41 3306". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 20 August 2020.
  11. ^ "BD+41 3306B". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 20 August 2020.
  12. ^ a b c Wall, Mike (27 January 2015). "Found! 5 Ancient Alien Planets Nearly As Old As the Universe". Space.com. Retrieved 27 January 2015.
  13. ^ a b c d Johnson, Michele (28 January 2015). "Astronomers Discover Ancient System with Five Small Planets". NASA. Retrieved 29 January 2015.
  14. AP News
    . Retrieved 27 January 2015.
  15. ^ a b Atkinson, Nancy (27 January 2015). "Oldest Planetary System Discovered, Improving the Chances for Intelligent Life Everywhere". Universe Today. Retrieved 27 January 2015.
  16. ^ a b c Staff (27 January 2015). "Exoplanet Catalog". Extrasolar Planets Encyclopaedia. Retrieved 27 January 2015.
  17. Caltech
    . Retrieved 28 January 2014.
  18. ^ a b Phil, Plait (28 January 2015). "Astronomers Find Ancient Earth-Sized Planets in Our Galactic Backyard". Slate. Retrieved 28 January 2015.
  19. doi:10.3847/1538-4365/ad0cab
    .
  20. S2CID 119325005
  21. doi:10.3847/2041-8213/aa6543
    .

External links
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