Kepler-444
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] |
Astrometry | |
Kepler-444 A | |
Radial velocity (Rv) | −123.05±0.17[7] km/s |
Proper motion (μ) | RA: 94.639(13) mas/yr[3] Dec.: −632.269(14) mas/yr[3] |
Parallax (π) | 27.3578 ± 0.0125 mas[3] |
Distance | 119.22 ± 0.05 ly (36.55 ± 0.02 pc) |
Kepler-444 B/C | |
Proper motion (μ) | RA: 94.508(55) mas/yr[5] Dec.: −630.781(78) mas/yr[5] |
Parallax (π) | 27.6079 ± 0.0545 mas[5] |
Distance | 118.1 ± 0.2 ly (36.22 ± 0.07 pc) |
Orbit[1] | |
Primary | A |
Companion | BC |
Period (P) | 324+31 −25 yr |
Semi-major axis (a) | 52.2+3.3 −2.7 AU |
Eccentricity (e) | 0.55+0.05 −0.05 |
Inclination (i) | 85.4+0.3 −0.4° |
Longitude of the node (Ω) | 250.7+0.2 −0.2° |
Periastron epoch (T) | JD 2537060+10881 −8533 |
Argument of periastron (ω) (secondary) | 227.3+6.5 −5.2° |
Details | |
A | |
Mass | 0.754±0.030[8] M☉ |
Radius | 0.753±0.010[8] R☉ |
Surface gravity (log g) | 4.595±0.060[2] cgs |
Temperature | 5046±74.0[2] K |
Metallicity [Fe/H] | −0.55±0.07[2] dex |
Rotation | 49.40±6.04 d[9] |
Age | 11.00±0.8[8] Gyr |
B | |
Mass | 0.307+0.009 −0.008[1] M☉ |
Surface gravity (log g) | 5.0±0.2[2] cgs |
Temperature | 3,464±200[2] K |
C | |
Mass | 0.296±0.008[1] M☉ |
Surface gravity (log g) | ~5[2] cgs |
Temperature | 3,500 - 4,000[2] K |
Other designations | |
Kepler-444A: Gaia DR2 2101486923385239808, HIP 94931, LHS 3450, TYC 3129-00329-1, 2MASS J19190052+4138043[10] | |
Kepler-444BC: Gaia DR2 2101486923382009472[11] | |
Database references | |
SIMBAD | data |
B/C |
Kepler-444 (or KOI-3158, KIC 6278762, 2MASS J19190052+4138043, BD+41°3306)[10] is a triple star system, estimated to be 11.2 billion years old (more than 80% of the age of the universe),[12] approximately 119 light-years (36 pc) away from Earth in the constellation Lyra. On 27 January 2015, the Kepler spacecraft is reported to have confirmed the detection of five sub-Earth-sized rocky exoplanets orbiting the main star. The star is a 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[edit]
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[edit]
On 28 January 2015, astronomers using data from NASA's Kepler Mission discovered an ancient triple star system with five 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[edit]
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[edit]
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[edit]
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.
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[edit]
- 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[edit]
- ^ a b c d e Zhang, Zhoujian; et al. (2023). "The McDonald Accelerating Stars Survey: Architecture of the Ancient Five-planet Host System Kepler-444". The Astronomical Journal. 165 (2) 73. arXiv:2210.07252. Bibcode:2023AJ....165...73Z. doi:10.3847/1538-3881/aca88c.
- ^ a b c d e f g h i Campante, T. L.; et al. (2015). "An Ancient Extrasolar System with Five Sub-Earth-size Planets". The Astrophysical Journal. 799 (2) 170. arXiv:1501.06227. Bibcode:2015ApJ...799..170C. doi:10.1088/0004-637X/799/2/170.
- ^ a b c d Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.</ref
- ^ a b c d Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ Wilson, O. C. (1962). "Relationship Between Colors and Spectra of Late Main-Sequence Stars". The Astrophysical Journal. 136: 793. Bibcode:1962ApJ...136..793W. doi:10.1086/147437.
- ^ a b Dupuy, Trent J.; et al. (2016). "Orbital Architectures of Planet-Hosting Binaries. I. Forming Five Small Planets in the Truncated Disk of Kepler-444A". The Astrophysical Journal. 817 (1) 80. arXiv:1512.03428. Bibcode:2016ApJ...817...80D. doi:10.3847/0004-637X/817/1/80.
- ^ a b c Buldgen, G.; et al. (2019). "Revisiting Kepler-444. I. Seismic modeling and inversions of stellar structure". Astronomy & Astrophysics. 630. A126. arXiv:1907.10315. Bibcode:2019A&A...630A.126B. doi:10.1051/0004-6361/201936126. S2CID 198229778.
- ^ Mazeh, Tsevi; et al. (2015). "Photometric Amplitude Distribution of Stellar Rotation of KOIs—Indication for Spin-Orbit Alignment of Cool Stars and High Obliquity for Hot Stars". The Astrophysical Journal. 801 (1). 3. arXiv:1501.01288. Bibcode:2015ApJ...801....3M. doi:10.1088/0004-637X/801/1/3.
- ^ a b "BD+41 3306". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 20 August 2020.
- ^ "BD+41 3306B". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 20 August 2020.
- ^ 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.
- ^ a b c d Johnson, Michele (28 January 2015). "Astronomers Discover Ancient System with Five Small Planets". NASA. Retrieved 29 January 2015.
- ^ Dunn, Marcia (27 January 2015). "Astronomers find solar system more than double ours in age". AP News. Retrieved 27 January 2015.
- ^ a b Atkinson, Nancy (27 January 2015). "Oldest Planetary System Discovered, Improving the Chances for Intelligent Life Everywhere". Universe Today. Retrieved 27 January 2015.
- ^ a b c Staff (27 January 2015). "Exoplanet Catalog". Extrasolar Planets Encyclopaedia. Retrieved 27 January 2015.
- ^ Staff (8 November 2013). "Second Kepler Science Conference - NASA Ames Research Center, Mountain View, CA - Nov. 4-8, 2013 - Agenda". Caltech. Retrieved 28 January 2014.
- ^ a b Phil, Plait (28 January 2015). "Astronomers Find Ancient Earth-Sized Planets in Our Galactic Backyard". Slate. Retrieved 28 January 2015.
- ^ Weiss, Lauren M.; et al. (1 January 2024). "The Kepler Giant Planet Search. I. A Decade of Kepler Planet-host Radial Velocities from W. M. Keck Observatory". The Astrophysical Journal Supplement Series. 270 (1) 8. arXiv:2304.00071. Bibcode:2024ApJS..270....8W. doi:10.3847/1538-4365/ad0cab.
- ^ Becker, Juliette C.; Adams, Fred C. (2017), "Effects of Unseen Additional Planetary Perturbers on Compact Extrasolar Planetary Systems", Monthly Notices of the Royal Astronomical Society, 468 (1): 549–563, arXiv:1702.07714, Bibcode:2017MNRAS.468..549B, doi:10.1093/mnras/stx461, S2CID 119325005
- ^ Mills, Sean M.; Fabrycky, Daniel C. (2017). "Mass, Density, and Formation Constraints in the Compact, Sub-Earth Kepler-444 System including Two Mars-mass Planets". The Astrophysical Journal Letters. 838 (1) L11. arXiv:1703.03417. Bibcode:2017ApJ...838L..11M. doi:10.3847/2041-8213/aa6543.