2 Equulei

{{Short description|Double star system in the constellation Equuleus}}

{{Starbox begin

| name = 2 Equulei

}}

{{Starbox observe 2s

| epoch = J2000.0

| equinox = J2000.0 (ICRS)

| constell = Equuleus

| component1 = A

| ra1 = {{RA|21|02|12.50262}}

| dec1 = {{DEC|+07|10|47.1545}}

| appmag_v1 = 7.41

| component2 = B

| ra2 = {{RA|21|02|12.39375}}

| dec2 = {{DEC|+07|10|44.7957}}

| appmag_v2 = 7.64

}}

{{Starbox character

| component1 = A

| type = subgiant

| class = F6V

| component2 = B

| type2 = subgiant

| class2 = F3V

}}

{{Starbox astrometry

| radial_v = {{Val|−4.8|1.6}}

| absmag_v = {{Val|2.16|0.18}}

}}

{{Starbox astrometry|no_heading=y

| component1 = A

| prop_mo_ra = −9.184

| prop_mo_dec = −12.915

| parallax = 8.8125

| p_error = 0.2481

| parallax_footnote =

| component2 = B

| prop_mo_ra2 = −4.238

| prop_mo_dec2 = −17.934

| parallax2 = 8.5577

| p_error2 = 0.0298

| parallax_footnote2 =

}}

{{Starbox detail

| component1 = 2 Equ A

| mass = 1.73

| radius = 2.6

| luminosity = 12.9

| temperature = 6,127

| gravity = 3.84

| metal_fe = 0.17

| rotational_velocity =

| age_gyr = 1.9

| component2 = 2 Equ B

| mass2 = 1.61

| radius2 = 2.8

| luminosity2 = 10.9

| temperature2 = 6,420

| gravity2 = 3.72

| metal_fe2 =

| rotational_velocity2 =

| age_gyr2 = 2.2

}}

{{Starbox catalog

| names = λ Equ, 2 Equulei, BD+06°4731, HD 200256, HIP 103813, LTT 16227, SAO 126482

}}

2 Equulei is a double star system in the constellation of Equuleus.

The primary component of the 2 Equulei pair is an F-type star. As of 2015, the secondary had an angular separation of {{val|2.90|ul=arc seconds}} along a position angle of 213° from the primary. They form a common proper motion pair, two stars at approximately the same distance and moving in the same direction. Gaia DR3 gives them parallaxes of {{val|8.8125|0.2471|ul=mas}} and {{val|8.5577|0.0298|u=mas}} respectively, although they are flagged as potentially unreliable. These parallaxes correspond to a distance of around {{val|380|ul=ly}}, in contrast to the Hipparcos distance of {{val|260|20|u=ly}} for the two stars as a pair.

2 Equulei has been referred to in some sources as λ (Lambda) Equulei, although it was not given that designation by Bayer.

References

{{reflist|refs=

{{cite journal |bibcode=1935ApJ....81..187A |title=The Spectroscopic Absolute Magnitudes and Parallaxes of 4179 Stars |last1=Adams |first1=Walter S. |last2=Joy |first2=Alfred H. |last3=Humason |first3=Milton L. |last4=Brayton |first4=Ada Margaret |journal=The Astrophysical Journal |date=1935 |volume=81 |page=187 |doi=10.1086/143628 }}

{{citation

| title=Validation of the new Hipparcos reduction

| last1=van Leeuwen | first1=F.

| journal=Astronomy and Astrophysics

| volume=474 | issue=2 | pages=653–664 | date=2007

| arxiv=0708.1752 | bibcode=2007A&A...474..653V

| doi=10.1051/0004-6361:20078357 | s2cid=18759600 | postscript=. }}

{{citation

| display-authors=1 | 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

| journal=Astronomy and Astrophysics

| volume=501 | issue=3 |date=July 2009 | pages=941–947

| doi=10.1051/0004-6361/200811191 | bibcode=2009A&A...501..941H

| arxiv=0811.3982 | s2cid=118577511 | postscript=. }}

{{citation

| last1=Casagrande | first1=L. | last2=Schönrich | first2=R.

| last3=Asplund | first3=M. | last4=Cassisi | first4=S.

| last5=Ramírez | first5=I. | last6=Meléndez | first6=J.

| last7=Bensby | first7=T. | last8=Feltzing | first8=S.

| title=New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey

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

| volume=530 | issue=A138 | pages=21 | date=2011

| doi=10.1051/0004-6361/201016276 | bibcode=2011A&A...530A.138C

| arxiv=1103.4651 | s2cid=56118016 | postscript=. }}

{{citation

| display-authors=1

| last1=Mason | first1=B. D.

| last2=Wycoff | first2=G. L.

| last3=Hartkopf | first3=W. I.

| last4=Douglass | first4=G. G.

| last5=Worley | first5=C. E.

| title=The Washington Visual Double Star Catalog

| url=http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=B/wds

| accessdate=2015-07-22

| doi = 10.1086/323920 | doi-access=free }}

{{citation

| title=2 Equ -- Double or multiple star

| work=SIMBAD Astronomical Database

| publisher=Centre de Données astronomiques de Strasbourg

| url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=2+Equ

| accessdate=2017-02-17 | postscript=. }}

{{cite journal|bibcode=2008ApJS..176..216A|title=Visual Multiples. IX. MK Spectral Types|journal=The Astrophysical Journal Supplement Series|volume=176|issue=1|pages=216–217|last1=Abt|first1=Helmut A.|year=2008|doi=10.1086/525529|doi-access=free}}

{{cite journal | last=Wagman | first=M. | title=Flamsteed's Missing Stars | journal=Journal for the History of Astronomy | issue=3 | volume=18 | page=215 | bibcode=1987JHA....18..209W |date=August 1987 | doi=10.1177/002182868701800305| s2cid=118445625 }}

}}

Category:F-type subgiants

Category:Double stars

Category:Equuleus

Equulei, Lambda

Category:Durchmusterung objects

Equulei, 02

200256

103813