Pi Aurigae

Pi Aurigae
Diagram showing star positions and boundaries of the Auriga constellation and its surroundings


The location of π Aurigae (circled)

Observation data
Epoch J2000      Equinox J2000
Constellation Auriga
Right ascension 05h 59m 56.0994s[1]
Declination +45° 56′ 12.248″[1]
Apparent magnitude (V) 4.25[2]
Characteristics
Spectral type M3 II[3]
U−B color index +1.83[2]
B−V color index +1.72[2]
R−I color index 1.48
Variable type LC[4]
Astrometry
Radial velocity (Rv)0.71 ± 0.76[5] km/s
Proper motion (μ) RA: -2.42[1] mas/yr
Dec.: -7.32[1] mas/yr
Parallax (π)3.88 ± 0.85[1] mas
Distanceapprox. 800 ly
(approx. 260 pc)
Details
Mass5.0 M☉
Radius265[6] R☉
Luminosity9590 L☉
Temperature3530 K
Age70-100 Myr
Other designations
35 Aurigae, BD+45 1217, HD 40239, HIP 28404, HR 2091, SAO 40756.[7]

Pi Aurigae (π Aur, π Aurigae) is the Bayer designation for a star in the northern constellation of Auriga. Located about one degree north of the 2nd magnitude star Beta Aurigae,[8] Pi Aurigae is visible to the naked eye with an apparent visual magnitude of 4.25[2] Based upon parallax measurements, it is approximately 800 light-years (250 parsecs) away from Earth.[1] At that distance, the brightness of the star is diminished by 0.54 in magnitude from extinction caused by interstellar gas and dust.[5]

Pi Aurigae is a bright giant star with a stellar classification of M3 II.[3] The measured angular diameter of this star, after correction for limb darkening, is 9.56 ± 0.10 mas.[9] At the estimated distance of Pi Aurigae,[1] this yields a physical size of about 265 times the radius of the Sun.[6] It is classified as an slow irregular variable of type LC and its brightness varies from magnitude +4.24 to +4.34.[4]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 van Leeuwen, Floor (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, arXiv:0708.1752v1, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. Note: see VizieR catalogue I/311.
  2. ↑ 2.0 2.1 2.2 2.3 Johnson, H. L. et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory 4 (99), Bibcode:1966CoLPL...4...99J.
  3. ↑ 3.0 3.1 Morgan, W. W.; Keenan, P. C. (1973), "Spectral Classification", Annual Review of Astronomy and Astrophysics 11: 29, Bibcode:1973ARA&A..11...29M, doi:10.1146/annurev.aa.11.090173.000333.
  4. ↑ 4.0 4.1 Ruban, E. V. et al. (September 2006), "Spectrophotometric observations of variable stars", Astronomy Letters 32 (9): 604–607, Bibcode:2006AstL...32..604R, doi:10.1134/S1063773706090052.
  5. ↑ 5.0 5.1 Famaey, B. et al. (January 2005), "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters", Astronomy and Astrophysics 430 (1): 165–186, arXiv:astro-ph/0409579, Bibcode:2005A&A...430..165F, doi:10.1051/0004-6361:20041272.
  6. ↑ 6.0 6.1 Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R*) is given by:
    \begin{align} 2\cdot R_* & = \frac{(258\cdot 9.56\cdot 10^{-3})\ \text{AU}}{0.0046491\ \text{AU}/R_{\bigodot}} \\ & \approx 530\cdot R_{\bigodot} \end{align}
  7. ↑ "pi. Aur -- Pulsating variable Star", SIMBAD Astronomical Database (Centre de Données astronomiques de Strasbourg), retrieved 2012-08-20.
  8. ↑ O'Meara, Stephen James (2007), Steve O'Meara's Herschel 400 Observing Guide, Cambridge University Press, p. 23, ISBN 0521858933.
  9. ↑ Richichi, A.; Percheron, I.; Khristoforova, M. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics 431: 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039.

External links