Pi2 Gruis

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

{{other stars by Bayer designation|Pi Gruis{{!}}π Gruis}}

{{Starbox begin

| name = Pi² Gruis

}}

{{Starbox observe

| epoch = J2000.0

| equinox = J2000.0 (ICRS)

| constell = Grus

| ra = {{RA|22|23|07.98704}}

| dec = {{DEC|−45|55|42.5582}}

| appmag_v = 5.622 {{nowrap|(5.71 + 11.3)}}

}}

{{Starbox character

| class = F3 III-IV or F0 V

| b-v = +0.365

| u-b = +0.016

| r-i =

| variable =

}}

{{Starbox astrometry

| radial_v = 3.0

| prop_mo_ra = +233.166

| prop_mo_dec = −58.205

| parallax = 25.1061

| p_error = 0.1256

| parallax_footnote =

| absmag_v = 2.62

}}

{{Starbox detail

| source =

| component1 = π² Gru A

| mass = 1.37

| radius = {{Val|1.93|0.07}}

| luminosity = {{Val|7.15|0.04}}

| temperature = {{Val|6788|138|101}}

| gravity = 4.20

| metal_fe = −0.06

| rotational_velocity =

| age_myr = 758

}}

{{Starbox catalog

| names = {{odlist | B=π² Gru | CD=−46°14295 | FK5=3786 | HD=212132 | HIP=110506 | HR=8524 | SAO=231111 | WDS=J22231-4556 }}

}}

{{Starbox reference

| Simbad = pi.02+Gru

}}

π² Gruis, Latinised as Pi² Gruis, is a binary star system in the southern constellation of Grus. It is faintly visible to the naked eye as a yellow-white hued star with an apparent visual magnitude of 5.622. Based upon an annual parallax shift of {{Val|25.1|ul=mas}} as seen from the Earth, the system is located 130 light years from the Sun.

The primary, component A, is an F-type star of uncertain luminosity class. Malaroda (1975) gave it a stellar classification of F3 III-IV, which would indicate an evolving subgiant/giant star hybrid spectrum, whereas Houk (1978) listed it as class F0 V, suggesting that it is an F-type main sequence star. It has been considered to be a chemically peculiar star, but this is now considered doubtful. It is 758 million years old with 1.4 times the mass of the Sun. The star is 1.9 times the Sun's radius and is radiating 7 times the luminosity of the Sun from its photosphere at an effective temperature of 6,788 K.

The companion is a magnitude 11.3 star at an angular separation of 4.6 arc seconds. Gaia Data Release 2 has measured a separate annual parallax for it of {{val|25.3266|0.0871|ul=mas}}, almost identical to the primary star, and indicates that it is a red dwarf.

References

{{reflist|refs=

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{{citation |bibcode=2009A&A...498..961R |title=Catalogue of Ap, HGMN and Am stars |journal=Astronomy and Astrophysics |volume=498 |issue=3 |pages=961 |last1=Renson |first1=P. |last2=Manfroid |first2=J. |year=2009 |doi=10.1051/0004-6361/200810788 |postscript=. |doi-access=free |url=https://zenodo.org/record/890529 }}

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

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

{{citation

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| title=A catalogue of multiplicity among bright stellar systems

| journal=Monthly Notices of the Royal Astronomical Society

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| bibcode=2008MNRAS.389..869E | doi=10.1111/j.1365-2966.2008.13596.x

| doi-access=free | arxiv=0806.2878 | s2cid=14878976 | postscript=. }}

{{citation

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

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

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| 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

| last1=David | first1=Trevor J. | last2=Hillenbrand | first2=Lynne A.

| title=The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets

| journal=The Astrophysical Journal

| volume=804 | issue=2 | pages=146 | year=2015

| bibcode=2015ApJ...804..146D | doi=10.1088/0004-637X/804/2/146

| arxiv=1501.03154 | s2cid=33401607 | postscript=. }}

{{citation

| last1=Houk | first1=N.

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

| volume=2 | date=1978 | postscript=.

| publisher=Dept. of Astronomy, University of Michigan

| bibcode=1978mcts.book.....H }}

{{citation

| last=Malaroda | first=S.