HD 20781

{{Short description|Star in a binary star system in the constellation Fornax}}

{{Starbox begin

| name = HD 20781

}}

{{Starbox observe

| epoch = J2000.0

| constell = Fornax

| ra = {{RA|03|20|02.94286}}

| dec = {{DEC|-28|47|01.7905}}

| appmag_v = 8.48

}}

{{Starbox character

| class = K0V

| variable =

| b-v = 0.82

}}

{{Starbox astrometry

| radial_v = {{val|40.27|0.12}}

| prop_mo_ra = {{val|348.869|0.015}}

| prop_mo_dec = {{val|-66.614|0.019}}

| pm_footnote =

| parallax = 27.8123

| p_error = 0.0239

| parallax_footnote =

| absmag_v = 5.70

}}

{{Starbox detail

| source =

| mass = 0.7

| radius =

| luminosity = 0.49{{±|0.04}}

| gravity = 4.37{{±|0.05}}

| temperature =5256{{±|29}}

| metal_fe = −0.11{{±|0.02}}

| rotation = 46.8{{±|4.4}} d

| rotational_velocity =1.1

| age_gyr =

}}

{{Starbox catalog

| names = CD–29° 1229, HIP 15526, LTT 1581, SAO 168468, 2MASS J03200291-2847016, Gaia DR1 5060105892897388288

}}

{{Starbox reference

|Simbad=HD+20781

}}

HD 20781 is a star which is part of a wide binary system with HD 20782. The companion star has a very large angular separation of 252 arcsec, corresponding to 9080 AU at the distance of HD 20782. Both stars possess their own planetary systems in S type orbits, with a total of five known planets around both stars. This is the first known example of planets being found orbiting both components of a wide binary system. HD 20781 has no noticeable starspot activity.

Planetary system

In 2011, a pair of Neptune-mass gas giants were detected with the radial velocity method. In 2017, these planets were confirmed and an additional two inner super-Earths were detected, with periods of 5.3 and 13.9 days respectively.

{{OrbitboxPlanet begin

| table_ref=

}}

{{OrbitboxPlanet

| exoplanet = b

| mass_earth = {{val|1.93|0.39|0.36|p=≥}}

| period = {{val|5.3135|0.0010}}

| semimajor = {{val|0.0529|0.0024|0.0027}}

| eccentricity = {{val|0.10|0.11|0.07}}

}}

{{OrbitboxPlanet

| exoplanet = c

| mass_earth = {{val|5.33|0.70|0.67|p=≥}}

| period = {{val|13.8905|0.0033|0.0034}}

| semimajor = {{val|0.1004|0.0046|0.0051}}

| eccentricity = {{val|0.09|0.09|0.06}}

}}

{{OrbitboxPlanet

| exoplanet = d

| mass_earth = {{val|10.61|1.20|1.19|p=≥}}

| period = {{val|29.1580|0.0102|0.0100}}

| semimajor = {{val|0.1647|0.0076|0.0083}}

| eccentricity = {{val|0.11|0.05|0.06}}

}}

{{OrbitboxPlanet

| exoplanet = e

| mass_earth = {{val|14.03|1.56|p=≥}}

| period = {{val|85.5073|0.0983|0.0947}}

| semimajor = {{val|0.3374|0.0155|0.0170}}

| eccentricity = {{val|0.06|0.06|0.04}}

}}

References

{{Reflist|refs=

{{cite journal | title=Identification of a Constellation From a Position | last1=Roman | first1=Nancy G. | journal=Publications of the Astronomical Society of the Pacific | volume=99 | issue=617 | pages=695–699 | date=1987 | bibcode=1987PASP...99..695R | doi=10.1086/132034 | doi-access=free }} [http://vizier.u-strasbg.fr/vizier/VizieR/constellations.htx Vizier query form ]

{{cite web | url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD+20781 | title=HD 20781 -- High proper-motion Star | website=SIMBAD Astronomical Database | publisher=Centre de données astronomiques de Strasbourg | access-date=2014-09-10}}

{{cite web |title=HD 20782 |url=https://exoplanetarchive.ipac.caltech.edu/overview/HD%2020781 |website=NASA Exoplanet Archive |access-date=12 November 2022}}

{{cite journal |last1=Desidera |first1=S. |last2=Barbieri |first2=M. |date=January 2007 |title=Properties of planets in binary systems. The role of binary separation |journal=Astronomy and Astrophysics |volume=462 |issue=1 |pages=345–353 |doi=10.1051/0004-6361:20066319 |arxiv=astro-ph/0610623 |bibcode=2007A&A...462..345D|s2cid=13813761 }}

{{cite arXiv |eprint=1109.2497 |class=astro-ph |title=The HARPS search for southern extra-solar planets XXXIV. Occurrence, mass distribution and orbital properties of super-Earths and Neptune-mass planets |last1=Mayor |first1=M. |last2=Marmier |first2=M. |last3=Lovis |first3=C. |last4=Udry |first4=S. |last5=Ségransan |first5=D. |last6=Pepe |first6=F. |last7=Benz |first7=W. |last8=Bertaux |first8=J.-L. |last9=Bouchy |first9=F. |last10=Dumusque |first10=X. |last11=Lo Curto |first11=G. |last12=Mordasini |first12=C. |last13=Queloz |first13=D. |last14=Santos |first14=N. C. |date=2011 |display-authors=2}}

{{cite journal |arxiv=1705.05153 |title=The HARPS search for southern extra-solar planets. XLIV. Eight HARPS multi-planet systems hosting 20 super-Earth and Neptune-mass companions |date=February 2019 |doi=10.1051/0004-6361/201731173 |last1=Udry |first1=S. |last2=Dumusque |first2=X. |last3=Lovis |first3=C. |last4=Segransan |first4=D. |last5=Diaz |first5=R. F. |last6=Benz |first6=W. |last7=Bouchy |first7=F. |last8=Coffinet |first8=A. |last9=Lo Curto |first9=G. |last10=Mayor |first10=M. |last11=Mordasini |first11=C. |last12=Motalebi |first12=F. |last13=Pepe |first13=F. |last14=Queloz |first14=D. |last15=Santos |first15=N. C. |last16=Wyttenbach |first16=A. |last17=Alonso |first17=R. |last18=Collier Cameron |first18=A. |last19=Deleuil |first19=M. |last20=Figueira |first20=P. |last21=Gillon |first21=M. |last22=Moutou |first22=C. |last23=Pollacco |first23=D. |last24=Pompei |first24=E. |display-authors=2 |journal=Astronomy & Astrophysics |volume=622 |page=A37 |bibcode=2019A&A...622A..37U |s2cid=119095511}}

}}

External links

{{cite encyclopedia | url=https://exoplanet.eu/catalog/hd_20781_c--946/| encyclopedia=Extrasolar Planets Encyclopaedia| title=Planet HD 20781 c|access-date=18 September 2020}}
{{cite encyclopedia | url=https://exoplanet.eu/catalog/hd_20781_b--945/| encyclopedia=Extrasolar Planets Encyclopaedia| title=Planet HD 20781 b|access-date=18 September 2020}}

Category:Fornax

Category:K-type main-sequence stars

020781

015526

Category:Planetary systems with four confirmed planets

Category:Durchmusterung objects

J03200291-2847016

HD 20781

Planetary system

See also

References

External links