16 Lyrae
{{Short description|Astrometric binary star system in the constellation Lyra}}
{{Starbox begin}}
{{Starbox observe
| epoch = J2000.0
| constell = Lyra
| dec = {{DEC|+46|56|05.1475}}
}}
{{Starbox character
| class = A6 IV or A7 V
| u-b =
| variable =
}}
{{Starbox astrometry
| radial_v = {{Val|+4.36|0.21}}
| prop_mo_ra = +22.004
| prop_mo_dec = {{val|-80.894}}
| parallax = 25.7832
| p_error = 0.0688
}}
{{Starbox detail
| mass = {{Val|1.722|0.013}}
| radius = {{val|1.644|0.025|0.023}} (equatorial)
{{val|1.622|0.023|0.022}} (polar)
| luminosity = {{val|10.45|0.30|0.28}}
| temperature = 8,028 (equator)
8,242 (polar)
| metal_fe =
| rotational_velocity = {{val|85.1|16.3|31.6}}
| age_myr = {{val|401|31|32}}
}}
{{Starbox catalog
| names = {{odlist | F=16 Lyr | NSV=11677 | BD=+46°2602 | HD=177196 | HIP=93408 | HR=7215 | SAO=48011 | GSC=03545-03041 | WDS=J19014+4656A }}
}}
{{Starbox reference
| Simbad=16+Lyr
}}
{{Starbox end}}
16 Lyrae is a suspected astrometric binary star system in the constellation Lyra, located 126 light years away from the Sun based on parallax. It is visible to the naked eye as a dim, white-hued star with a combined apparent visual magnitude of 5.00. The system is moving further away from the Earth with a heliocentric radial velocity of +4.36 km/s. It is a suspected member of the Ursa Major Moving Group stream.
Cowley et al. (1969) found a stellar classification of A7 V for the visible component, matching an A-type main-sequence star that is generating energy through hydrogen fusion at its core. Abt and Morrell (1995) instead listed a class of A6 IV, suggesting it has left the main sequence and become a subgiant star.
16 Lyrae is 72% more massive than the Sun and irradiates 10.5 times the Sun's luminosity. It is 401 million years old with a high rate of spin, showing a projected rotational velocity of 85 km/s. The fast rotation make this star slightly oblate, with an equatorial radius of {{solar radius|1.644}} and a polar radius of {{solar radius|1.622}}. Its effective temperature also vary across its surface due to rotation, from {{val|ul=K|8200|fmt=commas}} in the poles to {{val|u=K|8000|fmt=commas}} in the equator.
This system is a source for X-ray emission with a luminosity of {{Val|105.3e20|ul=W}}, which is most likely coming from the unseen companion.
References
{{reflist|30em|refs=
{{cite DR3|2131342100048643584}}
{{cite simbad | title=16 Lyr | access-date=2019-05-28 }}
| 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 | date=September 2008
| doi=10.1111/j.1365-2966.2008.13596.x | doi-access=free | postscript=.
| bibcode=2008MNRAS.389..869E |arxiv = 0806.2878 | s2cid=14878976 }}
| last1=Abt | first1=Helmut A. | last2=Morrell | first2=Nidia I
| title=The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars
| journal=Astrophysical Journal Supplement
| volume=99 | pages=135 | year=1995
| doi=10.1086/192182 | bibcode=1995ApJS...99..135A | doi-access=free }}
| title=XHIP: An extended hipparcos compilation
| last1=Anderson | first1=E. | last2=Francis | first2=Ch.
| journal=Astronomy Letters | postscript=.
| volume=38 | issue=5 | pages=331 | year=2012
| bibcode=2012AstL...38..331A | arxiv=1108.4971
| doi=10.1134/S1063773712050015 | s2cid=119257644 }}
| title=X-ray emission from A-type stars
| last1=Schröder | first1=C. | last2=Schmitt | first2=J. H. M. M.
| journal=Astronomy and Astrophysics | postscript=.
| volume=475 | issue=2 | date=November 2007 | pages=677–684
| doi=10.1051/0004-6361:20077429 | bibcode=2007A&A...475..677S | doi-access=free }}
| title=Rotational velocities of A-type stars. IV. Evolution of rotational velocities
| journal=Astronomy & Astrophysics
| volume=537 | id=A120 | year=2012
| last1=Zorec | first1=J. | last2=Royer | first2=F.
| pages=A120
| doi=10.1051/0004-6361/201117691 | bibcode=2012A&A...537A.120Z
| arxiv=1201.2052 | s2cid=55586789
| postscript=. }}
| 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 | arxiv=1501.03154
| doi=10.1088/0004-637X/804/2/146 | s2cid=33401607 | postscript=. }}
| display-authors=1 | last1=King | first1=Jeremy R.
| last2=Villarreal | first2=Adam R. | last3=Soderblom | first3=David R.
| last4=Gulliver | first4=Austin F. | last5=Adelman | first5=Saul J.
| title=Stellar Kinematic Groups. II. A Reexamination of the Membership, Activity, and Age of the Ursa Major Group
| journal=The Astronomical Journal
| volume=125 | issue=4 | pages=1980 | year=2003
| doi=10.1086/368241 | bibcode=2003AJ....125.1980K | url=https://tigerprints.clemson.edu/cgi/viewcontent.cgi?article=1248&context=physastro_pubs | doi-access=free }}
| last1=Cowley | first1=A. | last2=Cowley | first2=C.
| last3=Jaschek | first3=M. | last4=Jaschek | first4=C.
| title=A study of the bright A stars. I. A catalogue of spectral classifications
| display-authors=1 | journal=Astronomical Journal
| volume=74 | pages=375–406 | date=April 1969
| doi=10.1086/110819 | bibcode=1969AJ.....74..375C }}
}}
{{Stars of Lyra}}
Category:A-type main-sequence stars