Delta Equulei

{{Starbox begin

| name = Delta Equulei

}}

{{Starbox observe

| epoch = J2000.0

| equinox = J2000.0 (ICRS)

| constell = Equuleus

| ra = {{RA|21|14|28.81531}}

| dec = {{DEC|+10|00|25.1259}}

| appmag_v = {{nowrap|5.19 + 5.52}}

}}

{{Starbox character

| class = {{nowrap|F7V + F7V}}

| b-v = +0.49

| u-b = −0.03

| r-i =

| variable =

}}

{{Starbox astrometry

| radial_v = {{Val|−16.2|0.3}}

| prop_mo_ra = +42.39

| prop_mo_dec = −304.19

| parallax = 54.89

| p_error = 0.50

| parallax_footnote =

| absmag_v = +3.14

}}

{{Starbox orbit

| reference =

| period_unitless = {{Val|2084.03|0.10|u=d|fmt=commas}}

| axis_unitless = {{Val|231.9650|0.0080|u=mas}}

| eccentricity = {{Val|0.436851|0.000025}}

| inclination = {{Val|99.4083|0.0098}}

| node = {{Val|23.362|0.012}}

| periastron = {{Val|53112.071|0.052|u=MHJD}}

| periarg = {{Val|7.735|0.013}}

| k1 =

| k2 =

}}

{{Starbox detail

| source =

| component1 = δ Equ A

| mass = {{Val|1.192|0.012}}

| radius = {{Val|1.30|0.08}}

| luminosity = 2.25

| temperature = {{Val|6200|150|fmt=commas}}

| gravity =

| metal_fe = {{Val|−0.07|0.09}}

| rotational_velocity =

| age_gyr = 3.0

| component2 = δ Equ B

| mass2 = {{Val|1.187|0.012}}

| radius2 = {{Val|1.25|0.08}}

| luminosity2 = 2.07

| temperature2 = {{Val|6200|150|fmt=commas}}

}}

{{Starbox catalog

| names = δ Equ, 7 Equulei, BD+09°4746, GJ 822.0, HD 202275, HIP 104858, HR 8123, LTT 16227, SAO 126643

}}

{{Starbox reference

| Simbad = del+Equ

}}

Delta Equulei, Latinized from δ Equulei, is the second brightest star in the constellation Equuleus. Delta Equulei is a binary star system about 60 light years away, with components of class G0 and F5.{{cite web |publisher=University of Illinois Astronomy department |url=http://www.astro.uiuc.edu/~kaler/sow/deltaequ.html |title=Delta Equulei |url-status=dead |archiveurl=https://web.archive.org/web/20061216035035/http://www.astro.uiuc.edu/~kaler/sow/deltaequ.html |archivedate=2006-12-16 }} Their combined magnitude is 4.47, and their absolute magnitude is 3.142. There is controversy as to the exact masses of the stars. One study puts the larger at 1.22 solar masses and the smaller at 1.17, while another pegs them at 1.66 and 1.593. The luminosity of the larger star is calculated to be 2.23 solar, and the smaller to be 2.17.

System

William Herschel listed Delta Equulei as a wide binary. Friedrich Georg Wilhelm von Struve later showed this to be an unrelated optical double star. However his son Otto Wilhelm von Struve while making follow-up observations in 1852 found that while the separation of the optical double continued to increase, Delta Equulei itself appeared elongated. He concluded that it is a much more compact binary.

References

{{reflist|refs=

{{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

| title=XHIP: An extended hipparcos compilation

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

| journal=Astronomy Letters

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

| bibcode=2012AstL...38..331A | doi=10.1134/S1063773712050015

| arxiv=1108.4971 | s2cid=119257644 | postscript=. }}

{{citation

| last1=Mermilliod | first1=J.-C.

| title=Compilation of Eggen's UBV data, transformed to UBV (unpublished)

| journal=Catalogue of Eggen's UBV Data

| year=1986 | bibcode=1986EgUBV........0M | 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=Torres | first1=G.

| last2=Andersen | first2=J. | last3=Giménez | first3=A.

| title=Accurate masses and radii of normal stars: modern results and applications

| journal=The Astronomy and Astrophysics Review

| volume=18 | issue=1–2 | pages=67–126 | date=February 2010

| doi=10.1007/s00159-009-0025-1 | bibcode=2010A&ARv..18...67T

| arxiv=0908.2624 | s2cid=14006009 | postscript=. }}

{{citation

| last1=Malkov | first1=O. Yu. | last2=Tamazian | first2=V. S.

| last3=Docobo | first3=J. A. | last4=Chulkov | first4=D. A.

| title=Dynamical Masses of a Selected Sample of Orbital Binaries

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

| volume=546 | id=A69 | pages=5 | date=2012

| doi=10.1051/0004-6361/201219774 | bibcode =2012A&A...546A..69M | doi-access=free }}

{{citation

| title=Masses, Luminosities, and Orbital Coplanarities of the μ Orionis Quadruple-Star System from Phases Differential Astrometry

| display-authors=1 | last1=Muterspaugh | first1=Matthew W.

| last2=Lane | first2=Benjamin F. | last3=Fekel | first3=Francis C.

| last4=Konacki | first4=Maciej | last5=Burke | first5=Bernard F.

| last6=Kulkarni | first6=S. R. | last7=Colavita | first7=M. M.

| last8=Shao | first8=M. | last9=Wiktorowicz | first9=Sloane J.

| journal=The Astronomical Journal | postscript=.

| volume=135 | issue=3 | pages=766–776 | date=March 2008

| doi=10.1088/0004-6256/135/3/766 | bibcode=2008AJ....135..766M |arxiv = 0710.2126 | s2cid=6531922 }}

See Table 5.

{{cite journal | title=PHASES High-Precision Differential Astrometry of δ Equulei | last1=Muterspaugh | first1=Matthew W. | last2=Lane | first2=Benjamin F. | last3=Konacki | first3=Maciej | last4=Burke | first4=Bernard F. | last5=Colavita | first5=M. M. | last6=Kulkarni | first6=S. R. | last7=Shao | first7=M. | display-authors=1 | journal=The Astronomical Journal | volume=130 | issue=6 | pages=2866–2875 | year=2005 | arxiv=astro-ph/0507585 | bibcode=2005AJ....130.2866M | doi=10.1086/497035 | s2cid=12044718 }}

{{cite journal | title=On some lately discovered Double Stars | url=http://mnras.oxfordjournals.org/content/20/1/8.full.pdf | last1=Struve | first1=Otto Wilhelm | journal=Monthly Notices of the Royal Astronomical Society | volume=20 | pages=8–13 | year=1859 | bibcode=1859MNRAS..20....8S | doi=10.1093/mnras/20.1.8| doi-access=free }}

{{cite simbad

| title=del Equ

| accessdate=2017-02-17 }}

}}