Kepler-444#Planetary system

{{Short description|Triple star system in the constellation of Lyra}}

{{Starbox begin

| name = Kepler-444

}}

{{Starbox image

| image = 300px

| caption = Adaptive optics image of the Kepler-444 system from Zhang et al.

}}

{{Starbox observe 2s

| epoch = J2000

| equinox = 2000

| constell = Lyra

| component1 = Kepler-444 A

| ra1 = {{RA|19|19|00.5489}}

| dec1 = {{DEC|+41|38|04.582}}

| appmag_v1 = 8.86

| component2 = Kepler-444 B/C

| ra2 = {{RA|19|19|00.3922}}

| dec2 = {{DEC|+41|38|04.013}}

| appmag_v2 =

}}

{{Starbox character

| class = K0V

}}

{{Starbox astrometry

| component1 = Kepler-444 A

| radial_v = {{val|-123.05|0.17}}

| prop_mo_ra = {{val|94.639|(13)}}

| prop_mo_dec = {{val|−632.269|(14)}}

| pm_footnote =

| parallax = 27.3578

| p_error = 0.0125

| parallax_footnote =

| absmag_v =

| component2 = Kepler-444 B/C

| radial_v2 =

| prop_mo_ra2 = {{val|94.508|(55)}}

| prop_mo_dec2 = {{val|−630.781|(78)}}

| pm_footnote2 =

| parallax2 = 27.6079

| p_error2 = 0.0545

| parallax_footnote2 =

| absmag_v2 =

}}

{{Starbox orbit

| reference =

| primary = A

| name = BC

| axis_unitless = {{val|52.2|+3.3|−2.7}} AU

| eccentricity = {{val|0.55|+0.05|−0.05}}

| inclination = {{val|85.4|+0.3|−0.4}}

| node = {{val|250.7|+0.2|−0.2}}

| periarg = {{val|227.3|+6.5|−5.2}}

| period = {{val|324|+31|−25}}

| periastron = JD {{val|2537060|+10881|−8533}}

}}

{{Starbox detail

| component1 = A

| mass = {{val|0.754|0.030}}

| radius = {{val|0.753|0.010}}

| luminosity_bolometric =

| temperature = {{val|5046|74.0}}

| gravity = {{val|4.595|0.060}}

| metal_fe = {{val|−0.55|0.07}}

| rotation = {{val|49.40|6.04|u=days}}

| age_gyr = {{val|11.00|0.8}}

}}

{{Starbox detail |no_heading=y

| component1 = B

| mass = {{val|0.307|0.009|0.008}}

| temperature = {{val|3,464|200|fmt=commas}}

| gravity = {{val|5.0|0.2}}

| component2 = C

| mass2 = {{val|0.296|0.008}}

| temperature2 = 3,500 - 4,000

| gravity2 = ~5

}}

{{Starbox catalog

| names = {{odlist | 2MASS=J19190052+4138043 | BD=+41°3306 | KIC=6278762 | KOI=3158 | WDS=J19190+4138 }}

| component1 = Kepler-444A

| names1 = {{odlist | 2MASS=J19190052+4138043 | Gaia DR2=2101486923385239808 | HIP=94931 | LHS=3450 | TYC=3129-00329-1 }}

| component2 = Kepler-444BC

| names2 = {{odlist | Gaia DR2=2101486923382009472 }}

}}

{{Starbox reference

| Simbad = BD%2B41+3306

| Simbad2 = BD%2B41+3306B |sn2=B/C

| NSTED = Kepler-444

}}

Kepler-444 (or KOI-3158, KIC 6278762, 2MASS J19190052+4138043, BD+41°3306) is a triple star system, estimated to be 11.2 billion years old (more than 80% of the age of the universe), approximately {{convert|119|ly|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. All of the planets are far too close to their star to harbour life forms.

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.

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.

History

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

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. 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.

Stellar system

File:Radial velocity time series of Kepler 444.jpg

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.

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.

Radial velocity measurements of Kepler-444 show a linear trend, which aligns well with the orbit outlined by Dupuy et al. (see diagram above)

Planetary system

All five rocky exoplanets (Kepler-444b; Kepler-444c; Kepler-444d; Kepler-444e; Kepler-444f) are confirmed, 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. 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. 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. To keep the known planetary system stable, no additional giant planets can be located within 5.5 AU of the parent star.{{citation|arxiv=1702.07714|title=Effects of Unseen Additional Planetary Perturbers on Compact Extrasolar Planetary Systems|year=2017|doi=10.1093/mnras/stx461|last1=Becker|first1=Juliette C.|last2=Adams|first2=Fred C.|journal=Monthly Notices of the Royal Astronomical Society|volume=468|issue=1|pages=549–563|doi-access=free |bibcode=2017MNRAS.468..549B|s2cid=119325005}}

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.

A marginally significant peak appears at 72 days in the radial velocity data when the linear trend attributed to the stellar companions is subtracted. However, this signal suggests an eccentricity that is unphysically high, leading to orbits that would intersect the known planets. The signal likely stems from complexities within the long-term radial velocity signal of the Kepler-444 ABC system and may also be associated with the orbit of the BC pair.

{{OrbitboxPlanet begin

| table_ref = {{efn|The eccentricity has a non-Gaussian posterior distribution and so the median is an overestimate of the true eccentricity.}}

}}

{{OrbitboxPlanet

| exoplanet = b

| mass_earth = <0.079

| semimajor = {{val|0.04178|0.00079}}

| period = {{val|3.6001053|0.0000083|0.0000080}}

| eccentricity = {{val|0.16|0.21|0.10}}

| inclination = {{val|88.0|1.2|0.6}}

| radius_earth = {{val|0.406|0.013|0.013}}

}}

{{OrbitboxPlanet

| exoplanet = c

| mass_earth = <0.16

| semimajor = {{val|0.04881|0.00093}}

| period = {{val|4.5458841|0.0000070|0.0000071}}

| eccentricity = {{val|0.31|0.12|0.15}}

| inclination = {{val|88.2|1.2|1.0}}

| radius_earth = {{val|0.521|0.017|0.016}}

}}

{{OrbitboxPlanet

| exoplanet = d

| mass_earth = {{val|0.036|0.065|0.020}}

| semimajor = {{val|0.0600|0.0011}}

| period = {{val|6.189392|0.000012|0.000012}}

| eccentricity = {{val|0.18|0.16|0.12}}

| inclination = {{val|88.16|0.81|0.55}}

| radius_earth = {{val|0.540|0.017|0.016}}

}}

{{OrbitboxPlanet

| exoplanet = e

| mass_earth = {{val|0.034|0.059|0.019}}

| semimajor = {{val|0.0696|0.0013}}

| period = {{val|7.743493|0.000017|0.000016}}

| eccentricity = {{val|0.10|0.20|0.07}}

| inclination = {{val|89.13|0.54|0.52}}

| radius_earth = {{val|0.555|0.018|0.016}}

}}

{{OrbitboxPlanet

| exoplanet = f

| mass_earth = <0.22

| semimajor = {{val|0.0811|0.0015}}

| period = {{val|9.740486|0.000013|0.000013}}

| eccentricity = {{val|0.29|0.20|0.19}}

| inclination = {{val|87.96|0.36|0.31}}

| radius_earth = {{val|0.767|0.025|0.024}}

}}

Notes

References

{{Reflist|refs=

{{cite journal | title=Revisiting Kepler-444. I. Seismic modeling and inversions of stellar structure | last1=Buldgen | first1=G. | last2=Farnir | first2=M. | last3=Pezzotti | first3=C. | last4=Eggenberger | first4=P. | last5=Salmon | first5=S. J. A. J. | last6=Montalban | first6=J. | last7=Ferguson | first7=J. W. | last8=Khan | first8=S. | last9=Bourrier | first9=V. | last10=Rendle | first10=B. M. | last11=Meynet | first11=G. | last12=Miglio | first12=A. | last13=Noels | first13=A. | display-authors=1 | journal=Astronomy & Astrophysics | volume=630 | at=A126 | year=2019 | arxiv=1907.10315 | bibcode=2019A&A...630A.126B | doi=10.1051/0004-6361/201936126 | s2cid=198229778 }}

{{cite journal | title=An Ancient Extrasolar System with Five Sub-Earth-size Planets | last1=Campante | first1=T. L. | last2=Barclay | first2=T. | last3=Swift | first3=J. J. | last4=Huber | first4=D. | last5=Adibekyan | first5=V. Zh. | last6=Cochran | first6=W. | last7=Burke | first7=C. J. | last8=Isaacson | first8=H. | last9=Quintana | first9=E. V. | last10=Davies | first10=G. R. | last11=Silva Aguirre | first11=V. | last12=Ragozzine | first12=D. | last13=Riddle | first13=R. | last14=Baranec | first14=C. | last15=Basu | first15=S. | last16=Chaplin | first16=W. J. | last17=Christensen-Dalsgaard | first17=J. | last18=Metcalfe | first18=T. S. | last19=Bedding | first19=T. R. | last20=Handberg | first20=R. | last21=Stello | first21=D. | last22=Brewer | first22=J. M. | last23=Hekker | first23=S. | last24=Karoff | first24=C. | last25=Kolbl | first25=R. | last26=Law | first26=N. M. | last27=Lundkvist | first27=M. | last28=Miglio | first28=A. | last29=Rowe | first29=J. F. | last30=Santos | first30=N. C. | last31=Van Laerhoven | first31=C. | last32=Arentoft | first32=T. | last33=Elsworth | first33=Y. P. | last34=Fischer | first34=D. A. | last35=Kawaler | first35=S. D. | last36=Kjeldsen | first36=H. | last37=Lund | first37=M. N. | last38=Marcy | first38=G. W. | last39=Sousa | first39=S. G. | last40=Sozzetti | first40=A. | last41=White | first41=T. R. | display-authors=1 | journal=The Astrophysical Journal | volume=799 | issue=2 | article-number=170 | page= | year=2015 | arxiv=1501.06227 | bibcode=2015ApJ...799..170C | bibcode-access=free | doi=10.1088/0004-637X/799/2/170 | doi-access=free }}

{{cite journal | title=Orbital Architectures of Planet-Hosting Binaries. I. Forming Five Small Planets in the Truncated Disk of Kepler-444A | last1=Dupuy | first1=Trent J. | last2=Kratter | first2=Kaitlin M. | last3=Kraus | first3=Adam L. | last4=Isaacson | first4=Howard | last5=Mann | first5=Andrew W. | last6=Ireland | first6=Michael J. | last7=Howard | first7=Andrew W. | last8=Huber | first8=Daniel | display-authors=1 | journal=The Astrophysical Journal | volume=817 | issue=1 | article-number=80 | page= | year=2016 | arxiv=1512.03428 | bibcode=2016ApJ...817...80D | bibcode-access=free | doi=10.3847/0004-637X/817/1/80 | doi-access=free }}

{{cite journal | title=Photometric Amplitude Distribution of Stellar Rotation of KOIs—Indication for Spin-Orbit Alignment of Cool Stars and High Obliquity for Hot Stars | last1=Mazeh | first1=Tsevi | last2=Perets | first2=Hagai B. | last3=McQuillan | first3=Amy | last4=Goldstein | first4=Eyal S. | display-authors=1 | journal=The Astrophysical Journal | volume=801 | issue=1 | at=3 | year=2015 | arxiv=1501.01288 | bibcode=2015ApJ...801....3M | bibcode-access=free | doi=10.1088/0004-637X/801/1/3 | doi-access=free }}

{{cite journal | title=Mass, Density, and Formation Constraints in the Compact, Sub-Earth Kepler-444 System including Two Mars-mass Planets | last1=Mills | first1=Sean M. | last2=Fabrycky | first2=Daniel C. | journal=The Astrophysical Journal Letters | volume=838 | issue=1 | article-number=L11 | page= | year=2017 | arxiv=1703.03417 | bibcode=2017ApJ...838L..11M | bibcode-access=free | doi=10.3847/2041-8213/aa6543 | doi-access=free }}

{{cite web |last=Johnson |first=Michele |title=Astronomers Discover Ancient System with Five Small Planets |url=https://www.jpl.nasa.gov/news/astronomers-discover-ancient-system-with-five-small-planets |date=28 January 2015 |work=NASA |access-date=29 January 2015}}

{{cite news |last=Dunn |first=Marcia |title=Astronomers find solar system more than double ours in age |url=https://apnews.com/general-news-1b42cd9c22fa48a6b57fcbe1dccbd617 |date=27 January 2015 |work=AP News |access-date=27 January 2015}}

{{cite web |last1=Atkinson |first1=Nancy |title=Oldest Planetary System Discovered, Improving the Chances for Intelligent Life Everywhere |url=http://www.universetoday.com/118510/oldest-planetary-system-discovered-improving-the-chances-for-intelligent-life-everywhere/ |date=27 January 2015 |work=Universe Today |access-date=27 January 2015}}

{{cite web |last=Wall |first=Mike |title=Found! 5 Ancient Alien Planets Nearly As Old As the Universe |url=http://www.space.com/28386-ancient-alien-planets-discovery-kepler-444.html |date=27 January 2015 |work=Space.com |access-date=27 January 2015}}

{{cite web |author=Staff |title=Second Kepler Science Conference - NASA Ames Research Center, Mountain View, CA - Nov. 4-8, 2013 - Agenda |url=http://nexsci.caltech.edu/conferences/KeplerII/agenda.shtml |date=8 November 2013 |work=Caltech |access-date=28 January 2014}}

{{cite news |last=Phil |first=Plait |author-link=Phil Plait |title=Astronomers Find Ancient Earth-Sized Planets in Our Galactic Backyard |url=http://www.slate.com/blogs/bad_astronomy/2015/01/27/exoplanets_five_extremely_old_planets_found_around_kepler_444.html |date=28 January 2015 |work=Slate |access-date=28 January 2015}} is more than 80% of the age of the universe.

{{cite journal | title=The Kepler Giant Planet Search. I. A Decade of Kepler Planet-host Radial Velocities from W. M. Keck Observatory | last1=Weiss | first1=Lauren M. | last2=Isaacson | first2=Howard | last3=Howard | first3=Andrew W. | last4=Fulton | first4=Benjamin J. | last5=Petigura | first5=Erik A. | last6=Fabrycky | first6=Daniel | last7=Jontof-Hutter | first7=Daniel | last8=Steffen | first8=Jason H. | last9=Schlichting | first9=Hilke E. | last10=Wright | first10=Jason T. | last11=Beard | first11=Corey | last12=Brinkman | first12=Casey L. | last13=Chontos | first13=Ashley | last14=Giacalone | first14=Steven | last15=Hill | first15=Michelle L. | last16=Kosiarek | first16=Molly R. | last17=MacDougall | first17=Mason G. | last18=Močnik | first18=Teo | last19=Polanski | first19=Alex S. | last20=Turtelboom | first20=Emma V. | last21=Tyler | first21=Dakotah | last22=Van Zandt | first22=Judah | display-authors=1 | journal=The Astrophysical Journal Supplement Series | volume=270 | issue=1 | date=2024-01-01 | article-number=8 | page= | arxiv=2304.00071 | bibcode=2024ApJS..270....8W | bibcode-access=free | doi=10.3847/1538-4365/ad0cab | doi-access=free }}

{{cite journal |bibcode=1962ApJ...136..793W |title=Relationship Between Colors and Spectra of Late Main-Sequence Stars |last1=Wilson |first1=O. C. |journal=The Astrophysical Journal |year=1962 |volume=136 |page=793 |doi=10.1086/147437 |doi-access=free }}

{{cite journal|bibcode=2002yCat.2237....0D|title=VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system|journal=CDS/ADC Collection of Electronic Catalogues|volume=2237|author1=Ducati, J. R.|year=2002}}>

{{cite journal | title=The McDonald Accelerating Stars Survey: Architecture of the Ancient Five-planet Host System Kepler-444 | last1=Zhang | first1=Zhoujian | last2=Bowler | first2=Brendan P. | last3=Dupuy | first3=Trent J. | last4=Brandt | first4=Timothy D. | last5=Brandt | first5=G. Mirek | last6=Cochran | first6=William D. | last7=Endl | first7=Michael | last8=MacQueen | first8=Phillip J. | last9=Kratter | first9=Kaitlin M. | last10=Isaacson | first10=Howard T. | last11=Franson | first11=Kyle | last12=Kraus | first12=Adam L. | last13=Morley | first13=Caroline V. | last14=Zhou | first14=Yifan | display-authors=1 | journal=The Astronomical Journal | volume=165 | issue=2 | article-number=73 | page= | year=2023 | arxiv=2210.07252 | bibcode=2023AJ....165...73Z | bibcode-access=free | doi=10.3847/1538-3881/aca88c | doi-access=free }}

}}

External links

[http://exoplanetarchive.ipac.caltech.edu/cgi-bin/DisplayOverview/nph-DisplayOverview?objname=KOI-3158 NASA – Kepler-444/KOI-3158] at The NASA Exoplanet Archive
[https://exoplanet.eu/catalog/kepler_444_b--2364/ NASA – Kepler-444b]/[https://exoplanet.eu/catalog/kepler_444_c--2365/ c]/[https://exoplanet.eu/catalog/kepler_444_d--2366/ d]/[https://exoplanet.eu/catalog/kepler_444_e--2367/ e]/[https://exoplanet.eu/catalog/kepler_444_f--2368/ f] at Extrasolar Planets Encyclopaedia