Pi Aurigae

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title: "Pi Aurigae" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["m-type-bright-giants", "asymptotic-giant-branch-stars", "slow-irregular-variables", "auriga", "bayer-objects", "bright-star-catalogue-objects", "durchmusterung-objects", "flamsteed-objects", "henry-draper-catalogue-objects", "hipparcos-objects"] description: "Star in the constellation Auriga" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/Pi_Aurigae" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Star in the constellation Auriga ::

| image = | image=Auriga IAU.svg | float=center | width=240 | position=right | mark=Red circle.svg | mark_width=10 | mark_link=π Aur | x%=45.1 | y%=30.5 | caption = The location of π Aurigae (circled) | epoch = J2000 | ra = | dec = | appmag_v = 4.25 | constell = Auriga | type = asymptotic giant branch | class = M3 IIb | r-i = | v-r = | b-v = +1.72 | u-b = +1.83 | variable = LC | radial_v = | prop_mo_ra = −3.755 | prop_mo_dec = −7.785 | pm_footnote = | parallax = 4.515 | p_error = 0.241 | parallax_footnote = | absmag_v = −2.46 | mass = 2.98 | radius = 218.6 | luminosity = | temperature = | gravity = | metal_fe = | rotational_velocity = | age_myr = | names = | Simbad = pi+Aur

::figure[src="https://upload.wikimedia.org/wikipedia/commons/5/5f/Pi_Aurigae.jpg" caption="π Aurigae (center) in optical light"] ::

Pi Aurigae is a single, red-hued star in the northern constellation of Auriga. Its name is a Bayer designation that is Latinized from π Aurigae, and abbreviated Pi Aur or π Aur. Located about one degree north of the 2nd magnitude star Beta Aurigae, Pi Aurigae is visible to the naked eye with an apparent visual magnitude of 4.25 Based upon parallax measurements, it is approximately 720 ly away from Earth. At that distance, the brightness of the star is diminished by 0.54 in magnitude from extinction caused by interstellar gas and dust.

Pi Aurigae is an evolved bright giant star with a stellar classification of M3 IIb. After exhausting the supply of hydrogen at its core the star has expanded to approximately 219 times the size of the Sun. It is classified as a slow irregular variable of type LC and its brightness varies from magnitude +4.24 to +4.34. On average, the star is radiating 6,630 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,525 K.

References

| 28404 | mode=cs2 | postscript=.}}

| title=The Perkins catalog of revised MK types for the cooler stars | last1=Keenan | first1=Philip C. | last2=McNeil | first2=Raymond C. | journal=Astrophysical Journal Supplement Series | volume=71 | pages=245 | year=1989 | bibcode=1989ApJS...71..245K | doi=10.1086/191373 }}

References

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2. (2024). "Transferring spectroscopic stellar labels to 217 million Gaia DR3 XP stars with SHBoost". Astronomy and Astrophysics.
3. {{cite DR3. 196944217825405184
4. (January 2011). "Coudé-feed stellar spectral library - atmospheric parameters". Astronomy and Astrophysics.
5. (January 2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters". Astronomy and Astrophysics.
6. (October 2017). "Fundamental parameters and infrared excesses of Tycho-Gaia stars". Monthly Notices of the Royal Astronomical Society.
7. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory.
8. (September 2006). "Spectrophotometric observations of variable stars". Astronomy Letters.
9. "pi. Aur".
10. O'Meara, Stephen James. (2007). "Steve O'Meara's Herschel 400 Observing Guide". [[Cambridge University Press]].
11. Eggen, Olin J.. (July 1992). "Asymptotic giant branch stars near the sun". Astronomical Journal.

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::