Mu Lyrae

{{Starbox observe

| epoch = J2000

| constell = Lyra

| ra = {{RA|18|24|13.78599}}

| dec = {{DEC|+39|30|26.0473}}

| appmag_v = 5.11

}}

{{Starbox character

| type = subgiant

| class = A3IVn

| b-v = {{Val|+0.047|0.004}}

| u-b = +0.07

| variable =

}}

{{Starbox astrometry

| radial_v = {{Val|-24.0|4.2}}

| prop_mo_ra = {{val|-21.825|0.260}}

| prop_mo_dec = {{val|-4.460|0.288}}

| parallax = 7.9161

| p_error = 0.1438

| parallax_footnote =

| absmag_v = –0.53

}}

{{Starbox detail

| source =

| mass = {{Val|3.04|0.04}}

| radius = {{solar radius calculator|type=LT|1=200|2=9016|decimals=2}}0{{efn|name=radius}} (oblate)

| metal_fe =

| gravity =

| age_gyr =

| luminosity = {{Val|200|23|10}}

| temperature = {{Val|9016|167|165|fmt=commas}}

| rotational_velocity = 165

}}

{{Starbox catalog

| names = {{odlist | B=μ Lyr | F=2 Lyrae | BD=+39°3410 | HD=169702 | HIP=90191 | HR=6903 | SAO=66943 }}

}}

{{Starbox reference

| Simbad = 2+Lyr

}}

μ Lyrae, Latinized as Mu Lyrae, is a solitary star in the northern constellation Lyra. It has the traditional name Alathfar {{IPAc-en|@|'|l|æ|θ|f|ɑr}}, from the Arabic الأظفار al-ʼaẓfār "the talons (of the swooping eagle)", a name it shares with Eta Lyrae (though the latter is spelled "Aladfar" by the IAU). This white-hued object is visible to the naked eye as faint point of light with an apparent visual magnitude of 5.11. It is located approximately 412 light years distant from the Sun based on parallax, but is drifting closer with a radial velocity of −24 km/s.

This object has evolved off the main sequence, becoming a subgiant with a stellar classification of A0 IV. It has a fairly high rate of spin, showing a projected rotational velocity of 165 km/s. This is giving the star an equatorial bulge that is an estimated 17% larger than the polar radius. The star has three times the mass of the Sun and about 5.8 times the Sun's radius. It is radiating 200 times the Sun's luminosity from its photosphere at an effective temperature of 9,016 K.

Notes

{{Notelist|notes=

{{Efn|name=radius|1=Calculated, using the Stefan-Boltzmann law and the star's effective temperature and luminosity, with respect to the solar nominal effective temperature of 5,772 K: $\sqrt{\biggl(\frac{5,772}{9,016}\biggr)^4 \cdot 200} = 5.80\ R_\odot.$ }}

}}

References

{{reflist|refs=

{{citation

| last1=Zorec | first1=J. | last2=Royer | first2=F.

| title=Rotational velocities of A-type stars. IV. Evolution of rotational velocities

| journal=Astronomy & Astrophysics

| volume=537 | page=A120 | date=January 2012

| doi=10.1051/0004-6361/201117691 | bibcode=2012A&A...537A.120Z

| arxiv=1201.2052 | s2cid=55586789 | 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=van Belle | first1=Gerard T.

| title=Interferometric observations of rapidly rotating stars

| journal=The Astronomy and Astrophysics Review

| volume=20 | issue=1 | page=51 | date=March 2012

| bibcode=2012A&ARv..20...51V | arxiv=1204.2572

| doi=10.1007/s00159-012-0051-2 | s2cid=119273474

}}

{{cite journal

| 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

| bibcode=2008MNRAS.389..869E | arxiv=0806.2878

| doi=10.1111/j.1365-2966.2008.13596.x | doi-access=free | s2cid=14878976 }}

{{cite web

| url=https://www.iau.org/public/themes/naming_stars/

| title=Naming Stars | publisher=IAU.org

| accessdate=16 December 2017 }}

{{cite journal

| last=Mermilliod | first=J.-C.

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

| journal=Catalogue of Eggen's UBV Data

| date=1986 | bibcode=1986EgUBV........0M }}

{{cite journal

| last1=Van Belle | first1=Gerard T. | last2=von Braun | first2=Kaspar

| title=Directly Determined Linear Radii and Effective Temperatures of Exoplanet Host Stars

| journal=The Astrophysical Journal

| volume=694 | issue=2 | pages=1085–1098 | year=2009

| arxiv = 0901.1206 | bibcode =2009ApJ...694.1085V

| doi=10.1088/0004-637X/694/2/1085 | s2cid=18370219 }}

{{cite book

| first=Richard Hinckley | last=Allen

| title=Star-Names and Their Meanings

| url=https://books.google.com/books?id=TPJAvwEACAAJ

| publisher=Creative Media Partners, LLC

| isbn=978-0-344-21405-9 | date=2018 }}

}}

External links

{{cite web

| first=James B. | last=Kaler | date=October 7, 2011

| title=Al Athfar | website=STARS

| url=http://stars.astro.illinois.edu/sow/alathfar.html

| accessdate=2019-09-25 }}

Category:A-type subgiants

Category:Lyra

Lyrae, Mu

Category:Durchmusterung objects