21 Arietis

{{Short description|Binary star system in the constellation Aries}}

{{Starbox begin

| name = 21 Arietis

}}

{{Starbox observe

| epoch = J2000

| ra = {{RA|02|15|42.77662}}

| dec = {{DEC|+25|02|34.9627}}

| appmag_v = 5.57 (6.40/6.48)

| constell = Aries

}}

{{Starbox character

| class = F6 V

| r-i =

| v-r =

| b-v = +0.50

| u-b = +0.00

| variable =

}}

{{Starbox astrometry

| radial_v = −44.3

| prop_mo_ra = −89.72

| prop_mo_dec = −86.42

| parallax = 19.58

| p_error = 0.61

| parallax_footnote =

| absmag_v = 2.03

}}

{{Starbox orbit

| reference =

| period = {{nowrap|23.70 ± 0.12}}

| axis = {{nowrap|0.2353 ± 0.0011}}

| eccentricity = {{nowrap|0.6816 ± 0.0037}}

| inclination = {{nowrap|104.52 ± 0.16}}

| node = {{nowrap|236.44 ± 0.22}}

| periastron = {{nowrap|1986.192 ± 0.012}}

| periarg = {{nowrap|84.16 ± 0.16}}

}}

{{Starbox detail

| component1 = 21 Ari A

| mass = 1.338 ± 0.032

| radius =

| luminosity =

| temperature = 6,299

| metal_fe = +0.02

| gravity = 4.12

| rotational_velocity = 12.6

| age_gyr = 2.2

| component2 = 21 Ari B

| mass2 = 1.374 ± 0.027

}}

{{Starbox catalog

| names= BD+24 329, FK5 1059, HD 13872, HIP 10535, HR 657, SAO 75238, WDS J02157+2503.

}}

{{Starbox reference

| Simbad=21+Ari

}}

21 Arietis (abbreviated 21 Ari) is a binary star system in the northern constellation of Aries. 21 Arietis is the Flamsteed designation. It has a combined apparent visual magnitude is 5.57; the brighter member is magnitude 6.40 while the fainter star is magnitude 6.48. The distance to this star system, based upon an annual parallax shift of 19.58 mas, is {{Convert|167|ly|pc|abbr=off|lk=on}}. The pair orbit each other with a period of 23.70 years and an eccentricity of 0.68.

The system was initially thought to be a triple system in 1981, since the orbit of the system predicted a mass greater than would be expected from its F6V spectral type.{{cite journal|bibcode=1982A&A...105..323C|title=Is 21 Ari {{=}} Cou 79 a multiple system?|author1=Couteau, P.|author2=Morel, P. J.|journal=Astronomy and Astrophysics|volume=105|page=323|date=1982}} This was later rejected because the distance to the system was overestimated. However, while observing the spectrum of the system, it was found that a giant planet may be causing radial velocity variations. The purported planet would have a mass of {{Jupiter mass|1.40 ± 0.36}}, an orbital period of 925 days and orbit the primary star.{{cite journal|bibcode=2010AJ....140.1657M|doi=10.1088/0004-6256/140/6/1657|arxiv=1010.4048|title=The Phases Differential Astrometry Data Archive. V. Candidate Substellar Companions to Binary Systems|journal=The Astronomical Journal|volume=140|issue=6|pages=1657|year=2010|last1=Muterspaugh|first1=Matthew W.|last2=Lane|first2=Benjamin F.|last3=Kulkarni|first3=S. R.|last4=Konacki|first4=Maciej|last5=Burke|first5=Bernard F.|last6=Colavita|first6=M. M.|last7=Shao|first7=M.|last8=Hartkopf|first8=William I.|last9=Boss|first9=Alan P.|last10=Williamson|first10=M.|s2cid=59585356}}

References

{{reflist|refs=

{{citation | first=F. | last=van Leeuwen |date=November 2007 | title=Validation of the new Hipparcos reduction | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 | arxiv=0708.1752 | s2cid=18759600 | postscript=. }}

{{citation | last1=Balachandran | first1=Suchitra | title=Lithium depletion and rotation in main-sequence stars | journal=Astrophysical Journal, Part 1 | volume=354 | date=May 1, 1990 | pages=310–332 | doi=10.1086/168691 | bibcode=1990ApJ...354..310B | postscript=. }}

{{citation | last1=Harlan | first1=E. A. | title=MK classifications for F- and G-type stars. I | journal=Astronomical Journal | volume=74 | pages=916–919 | doi=10.1086/110881 | bibcode=1969AJ.....74..916H | postscript=. |date=September 1969}}

{{citation | last1=Schröder | first1=C. | last2=Reiners | first2=Ansgar | last3=Schmitt | first3=Jürgen H. M. M. | title=Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo | journal=Astronomy and Astrophysics | volume=493 | issue=3 | pages=1099–1107 | date=January 2009 | doi=10.1051/0004-6361:200810377 | bibcode=2009A&A...493.1099S | doi-access=free | url=http://goedoc.uni-goettingen.de/goescholar/bitstream/handle/1/9690/aa10377-08.pdf?sequence=2 }}{{Dead link|date=July 2023 |bot=InternetArchiveBot |fix-attempted=yes }}

{{citation | last1=Holmberg | first1=J. | last2=Nordström | first2=B. | last3=Andersen | first3=J. | title=The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics | volume=501 | issue=3 |date=July 2009 | pages=941–947 | doi=10.1051/0004-6361/200811191 | journal=Astronomy and Astrophysics | bibcode=2009A&A...501..941H | postscript=. |arxiv = 0811.3982 | s2cid=118577511 }}

{{citation | last1=Eggleton | first1=P. P. | last2=Tokovinin | first2=A. A. | title=A catalogue of multiplicity among bright stellar systems | journal=Monthly Notices of the Royal Astronomical Society | volume=389 | issue=2 | pages=869–879 | doi=10.1111/j.1365-2966.2008.13596.x | bibcode=2008MNRAS.389..869E | arxiv=0806.2878 | postscript=. |date=September 2008| doi-access=free | s2cid=14878976 }}

{{citation | last1=Hartkopf | first1=William I. | last2=Mason | first2=Brian D. | last3=McAlister | first3=Harold A. | title=Binary Star Orbits From Speckle Interferometry. VIII. Orbits of 37 Close Visual System | journal=Astronomical Journal | volume=111 | page=370 | doi=10.1086/117790 | bibcode=1996AJ....111..370H | postscript=. |date=January 1996| doi-access=free }}

}}

External links

[http://webviz.u-strasbg.fr/viz-bin/VizieR-S?HR%20657 HR 657]
[http://webviz.u-strasbg.fr/viz-bin/VizieR-S?CCDM%20J02157%2b2503AB CCDM J02157+2503]
[http://aladin.u-strasbg.fr/AladinPreview?-c=02+15+42.7773%2B25+02+34.956&ident=CCDM+J02157%2B2503AB&submit=Aladin+previewer Image 21 Arietis]

013872

Category:Binary stars

010535

Category:F-type main-sequence stars

Arietis, 21

Category:Aries (constellation)

Category:Durchmusterung objects

0657