Pi1 Ursae Majoris
{{short description|Star in the constellation Ursa Major}}
{{For|other stars with this name|Pi Ursae Majoris|Muscida}}
{{DISPLAYTITLE:Pi1 Ursae Majoris}}
{{Starbox begin
| name = Pi1 Ursae Majoris
}}
{{Starbox image
| image ={{Location map|100x100
|AlternativeMap=Ursa Major IAU.svg
|caption=
|alt=Diagram showing star positions and boundaries of the Centaurus constellation and its surroundings
|width=320
|lat=80.6 |long=68.4
|mark=Cercle rouge 100%.svg | marksize=12
|float=center
}}| caption=Location of π¹ Ursae Majoris (circled)
}}
{{Starbox observe
| epoch = J2000
| constell = Ursa Major
| dec = {{DEC|+65|01|15.2667}}
| appmag_v = 5.63
}}
{{Starbox character
| variable=BY Draconis }}
{{Starbox astrometry
| radial_v = {{nowrap|–13.88 ± 0.47}}
| prop_mo_ra ={{nowrap|-27.44 ± 0.31}}
| prop_mo_dec ={{nowrap|+88.13 ± 0.26}}
| parallax = 69.66
| p_error = 0.37
}}
{{Starbox detail
| radius=
| temperature={{nowrap|5,884 ± 6.8}}
}}
{{Starbox catalog
| names=π¹ Ursae Majoris, π¹ UMa, Pi1 UMa, 3 Ursae Majoris, BD +65°643, GC 11817, HD 72905, HIP 42438, HR 3391, PPM 16705, SAO 14609.}}
{{Starbox reference
|Simbad=pi1+UMa
}}
{{Starbox end}}
File:Pi1UMaLightCurve.png for pi1 Ursae Majoris, plotted from TESS data. The main plot shows the variation over several weeks, and the inset plot shows the same data folded, assuming a 4.9 day period, and averaged into 250 phase bins.]]
Pi1 Ursae Majoris (Pi1 UMa, π¹ Ursae Majoris, π¹ UMa) is a yellow G-type main sequence dwarf with a mean apparent magnitude of +5.63. It is approximately 46.8 light years from Earth, and is a relatively young star with an age of about 200 million years. It is classified as a BY Draconis type variable star and its brightness varies by 0.08 magnitudes. In 1986, it became the first solar-type star to have the emission from an X-ray flare observed. Based upon its space velocity components, this star is a member of the Ursa Major moving group of stars that share a common motion through space.
An excess of infrared radiation has been detected from this system, which suggests the presence of a debris disk. The best fit to the data indicates that there is a ring of fine debris out to a radius of about 0.4 AU, consisting of 0.25 μm grains of amorphous silicates or crystalline forsterite. There may also be a wider ring of larger (10 μm) grains out to a distance of 16 AU.
Naming and etymology
With π2, σ1, σ2, ρ, A and d, it composed the Arabic asterism Al Ṭhibā᾽, the Gazelle. According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al Ṭhibā were the title for seven stars : A as Althiba I, this star (π1) as Althiba II, π2 as Althiba III, ρ as Althiba IV, σ1 as Althiba V, σ2 as Althiba VI, and d as Althiba VII.
References
{{reflist|35em|refs=
| 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
| volume=501 | issue=3 |date=July 2009 | pages=941–947
| journal=Astronomy and Astrophysics
| doi=10.1051/0004-6361/200811191 | bibcode=2009A&A...501..941H
| arxiv=0811.3982 | s2cid=118577511 | postscript=. }}
{{citation | display-authors=1 | last1=Kovtyukh | first1=V. V. | last2=Soubiran | first2=C. | last3=Belik | first3=S. I. | last4=Gorlova | first4=N. I. | title=High precision effective temperatures for 181 F-K dwarfs from line-depth ratios | journal=Astronomy and Astrophysics | volume=411 | issue=3 | pages=559–564 | year=2003 | doi=10.1051/0004-6361:20031378 | bibcode=2003A&A...411..559K |arxiv=astro-ph/0308429 | s2cid=18478960 }}
{{citation | display-authors=1 | last1=Montes | first1=D. | last2=López-Santiago | first2=J. | last3=Gálvez | first3=M. C. | last4=Fernández-Figueroa | first4=M. J. | last5=De Castro | first5=E. | last6=Cornide | first6=M. | title=Late-type members of young stellar kinematic groups - I. Single stars | journal=Monthly Notices of the Royal Astronomical Society | volume=328 | issue=1 | pages=45–63 | date=November 2001 | doi=10.1046/j.1365-8711.2001.04781.x | doi-access=free | bibcode=2001MNRAS.328...45M | arxiv=astro-ph/0106537 | s2cid=55727428 }}
}}
External links
- [http://sco.stsci.edu/starvault/detail.php?starchoice=42438 TPF-C data for Hip 42438]{{dead link|date=January 2018 |bot=InternetArchiveBot |fix-attempted=yes }}
- [https://web.archive.org/web/20051109093754/http://aanda.u-strasbg.fr:2002/papers/aa/full/2001/45/aa1718/node6.html#SECTION000610000000000000000 Individual results for HD 72905]
{{Stars of Ursa Major}}
{{DEFAULTSORT:Pi Ursae Majoris}}
Category:G-type main-sequence stars
Category:BY Draconis variables