HD 6718

{{Starbox observe

| epoch = J2000.0

| constell = Cetus

| ra = {{RA|01|07|48.6630}}

| dec = {{DEC|–08|14|01.3306}}

| appmag_v = 8.45

}}

{{Starbox character

| type = main sequence

| class = G5V

| appmag_1_passband = B

| appmag_1 = 9.087

| appmag_2_passband = J

| appmag_2 = 7.269

| appmag_3_passband = H

| appmag_3 = 6.99

| appmag_4_passband = K

| appmag_4 = 6.876

| b-v = {{Val|0.662|0.009}}

| u-b =

| variable =

}}

{{Starbox astrometry

| radial_v = +34.76

| prop_mo_ra = {{val|192.637|0.114}}

| prop_mo_dec = {{val|20.080|0.069}}

| parallax = 19.4476

| p_error = 0.0523

| parallax_footnote =

| absmag_v = 4.754

}}

{{Starbox detail

| mass = {{Val|0.98|0.04}}

| radius = {{Val|1.01|0.02}}

| gravity = {{Val|4.42|0.02}}

| luminosity = {{Val|1.07|0.01}}

| temperature = {{Val|5728|5|fmt=commas}}

| metal_fe = {{Val|−0.064|0.004}}

| age_gyr = {{Val|6.0|2.4}}

| rotational_velocity = {{Val|2.00|0.12}}

}}

{{Starbox catalog

| names = {{odlist | BD=–09°221 | HD=6718 | HIP=5301 | SAO=129137 | LTT=641 | NLTT=3753 | PPM=183064 }}

}}

{{Starbox reference

| Simbad = HD+6718

| NSTED = HD+6718

| EPE = HD+6718

}}

HD 6718 is a solar twin star in the equatorial constellation of Cetus. It has a yellow hue but is too faint to be viewed with the naked eye, having an apparent visual magnitude of 8.45. The distance to this object, as determined from parallax measurements, is 168 light years. It is drifting away from the Sun with a radial velocity of +35 km/s.

This object is an ordinary G-type main-sequence star with a stellar classification of G5V, with the luminosity class of 'V' indicating it is generating energy through hydrogen fusion at its core. It is around six billion years old with a leisurely rotation rate, having a projected rotational velocity of 2 km/s. The level of magnetic activity in the chromosphere is considered very low and it has a near solar metallicity. Being a solar twin, has nearly the same mass and radius as the Sun. The star is radiating 1.07 times the luminosity of the Sun from its photosphere at an effective temperature of 5,728 K.

In 2009, a substellar companion (HD 6718 b) with a minimum mass of {{Jupiter mass|1.56|link=y}} was found in orbit around the star with a period of {{Convert|2496|days|years|disp=out|abbr=off}}. In 2020, the inclination of this object was measured, revealing its true mass to be {{Jupiter mass|62.8|link=y}}. This makes it a brown dwarf.

{{OrbitboxPlanet begin

| table_ref =

}}

{{OrbitboxPlanet

| exoplanet = b

| mass = {{val|62.79|16.98|13.80}}

| period = {{val|2496|176}}

| semimajor = {{val|3.56|0.24|0.15}}

| eccentricity = {{val|0.10|0.11|0.04}}

| inclination = {{val|1.488|0.410|0.310}}

}}

References

{{Reflist|refs=

{{cite journal

| last1=Anderson | first1=E. | last2=Francis | first2=Ch.

| title=XHIP: An extended hipparcos compilation

| journal=Astronomy Letters

| volume=38 | issue=5 | pages=331 | year=2012

| bibcode=2012AstL...38..331A | arxiv=1108.4971

| doi=10.1134/S1063773712050015 | s2cid=119257644 }}

{{cite journal

| title=Revising the ages of planet-hosting stars

| url=http://www.aanda.org/articles/aa/full_html/2015/03/aa24951-14/aa24951-14.html

| last1=Bonfanti | first1=A. | last2=Ortolani | first2=S.

| last3=Piotto | first3=G. | last4=Nascimbeni | first4=V.

| display-authors=1 | journal=Astronomy and Astrophysics

| volume=575 | at=A18 | year=2015

| arxiv=1411.4302 | bibcode=2015A&A...575A..18B

| doi=10.1051/0004-6361/201424951 | s2cid=54555839

}}

{{Cite journal

| display-authors=4 | last1=Cutri | first1=R. M.

| last2=Skrutskie | first2=M. F. | last3=Van Dyk | first3=S.

| last4=Beichman | first4=C. A. | last5=Carpenter | first5=J. M.

| last6=Chester | first6=T. | last7=Cambresy | first7=L.

| last8=Evans | first8=T. | last9=Fowler | first9=J.

| title=2MASS All Sky Catalog of point sources

| journal=The IRSA 2MASS All-Sky Point Source Catalog, NASA/IPAC Infrared Science Archive.

| date=June 2003 | bibcode=2003tmc..book.....C }}

{{citation

| title=The Solar Twin Planet Search. IV. The Sun as a typical rotator and evidence for a new rotational braking law for Sun-like stars

| display-authors=1 | last1=dos Santos | first1=Leonardo A.

| last2=Meléndez | first2=Jorge | last3=do Nascimento | first3=José-Dias

| last4=Bedell | first4=Megan | last5=Ramírez | first5=Iván

| last6=Bean | first6=Jacob L. | last7=Asplund | first7=Martin

| last8=Spina | first8=Lorenzo | last9=Dreizler | first9=Stefan

| last10=Alves-Brito | first10=Alan | last11=Casagrande | first11=Luca

| journal=Astronomy & Astrophysics | postscript=.

| volume=592 | id=A156 | pages=8 | date=August 2016

| doi=10.1051/0004-6361/201628558 | bibcode=2016A&A...592A.156D |arxiv = 1606.06214 | s2cid=53533614 }}

{{Cite book

| display-authors=1 | last1=Høg | first1=E.

| last2=Fabricius | first2=C. | last3=Makarov | first3=V. V.

| last4=Urban | first4=S. | last5=Corbin | first5=T.

| last6=Wycoff | first6=G. | last7=Bastian | first7=U.

| last8=Schwekendiek | first8=P. | last9=Wicenec | first9=A.

| title=The Tycho-2 catalogue of the 2.5 million brightest stars

| journal=Astronomy and Astrophysics

| volume=355 | pages=L27 | date=2000

| doi=10.1888/0333750888/2862 | isbn=978-0333750889

| bibcode=2000A&A...355L..27H }}

{{cite journal

| title=Michigan catalogue of two-dimensional spectral types for the HD Stars

| journal=Michigan Spectral Survey

| last1=Houk | first1=N. | last2=Swift | first2=C.

| volume=5 | year=1999 | bibcode=1999MSS...C05....0H }}

{{cite journal | title=Determining the true mass of radial-velocity exoplanets with Gaia. Nine planet candidates in the brown dwarf or stellar regime and 27 confirmed planets | last1=Kiefer | first1=F. | last2=Hébrard | first2=G. | last3=Lecavelier des Etangs | first3=A. | last4=Martioli | first4=E. | last5=Dalal | first5=S. | last6=Vidal-Madjar | first6=A. | display-authors=1 | journal=Astronomy & Astrophysics | volume=645 | page= | article-number=A7 | date=January 2021 | arxiv=2009.14164 | bibcode=2021A&A...645A...7K | bibcode-access=free | doi=10.1051/0004-6361/202039168 | doi-access=free | s2cid=221995447 }}

{{cite journal |doi=10.1051/0004-6361/200913616 |title=The HARPS Search for Southern Extrasolar Planets XXIII. 8 Planetary Companions to Low-activity Solar-type Stars |last1=Naef |first1=Dominique |last2=Mayor |first2=Michel |last3=Lo Curto |first3=Gaspare |last4=Bouchy |first4=François |last5=Lovis |first5=Christophe |last6=Moutou |first6=Claire |last7=Benz |first7=Willy |last8=Pepe |first8=Francesco |last9=Queloz |first9=Didier |last10=Santos |first10=Nuno C. |last11=Ségransan |first11=Damien |last12=Udry |first12=Stéphane |last13=Bonfils |first13=Xavier |last14=Delfosse |first14=Xavier |last15=Forveille |first15=Thierry |last16=Hébrard |first16=Guillaume |last17=Mordasini |first17=Christoph |last18=Perrier |first18=Christian |last19=Boisse |first19=Isabelle |last20=Sosnowska |first20=Danuta |journal=Astronomy and Astrophysics |volume=523 |page=A15 |year=2010 |arxiv=1008.4600 |bibcode=2010A&A...523A..15N |s2cid=118845989 |url=http://www.aanda.org/articles/aa/full_html/2010/15/aa13616-09/aa13616-09.html }}

{{cite journal

| title=The Solar Twin Planet Search. I. Fundamental parameters of the stellar sample

| display-authors=1 | last1=Ramírez | first1=I.

| last2=Meléndez | first2=J. | last3=Bean | first3=J.

| last4=Asplund | first4=M. | last5=Bedell | first5=M.

| last6=Monroe | first6=T. | last7=Casagrande | first7=L.

| last8=Schirbel | first8=L. | last9=Dreizler | first9=S.

| last10=Teske | first10=J. | last11=Tucci Maia | first11=M.

| last12=Alves-Brito | first12=A. | last13=Baumann | first13=P.

| journal=Astronomy & Astrophysics

| volume=572 | id=A48 | pages=19 | date=December 2014

| arxiv=1408.4130 | bibcode=2014A&A...572A..48R