9 Aurigae

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title: "9 Aurigae" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["flamsteed-objects", "durchmusterung-objects", "gliese-and-gj-objects", "henry-draper-catalogue-objects", "hipparcos-objects", "bright-star-catalogue-objects", "spectroscopic-binaries", "multiple-star-systems", "auriga", "gamma-doradus-variables", "f-type-main-sequence-stars", "objects-with-variable-star-designations"] description: "Multiple star system in the constellation Auriga" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/9_Aurigae" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Multiple star system in the constellation Auriga ::

| image= |image=Auriga constellation map.svg|alt=|float=center|width=240 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=9 Aurigae |x=628|y=118 |caption=Location of 9 Aurigae (circled) |epoch=J2000 |constell=Auriga |ra= |dec= |appmag_v=4.93 - 5.03 |class=F2V |b-v=+0.34 |u-b=−0.03 |variable=γ Dor |component1=A |radial_v= |prop_mo_ra=−28.557 |prop_mo_dec=−171.822 |parallax=37.0551 |p_error=0.1371 |parallax_footnote= |component1=B |radial_v= |prop_mo_ra=−54.582 |prop_mo_dec=−156.009 |parallax=37.0796 |p_error=0.0631 |parallax_footnote= |component1=C |radial_v= |prop_mo_ra=−32.386 |prop_mo_dec=−173.026 |parallax=37.2115 |p_error=0.0184 |parallax_footnote= | reference = | period_unitless = | eccentricity = 0.37 | k1 = 5.8 | component1 = A |mass = 1.97 |radius=1.56 |temperature=7,023 |gravity=4.07 |rotational_velocity=21.0 |luminosity=6.042 |metal_fe = −0.12 | component1 = B | mass = 0.49 | temperature = 4,947 | component2 = C | mass2 = 0.751 | temperature2 = 4,633 | radius2 = 0.756 | luminosity2 = 0.162 |names= |Simbad=9+Aur+A|sn=9 Aur A |Simbad2=9+Aur+B|sn2=9 Aur B |Simbad3=9+Aur+C|sn3=9 Aur C 9 Aurigae (9 Aur) is a star system in the constellation Auriga. It has an apparent magnitude of about 5, making it visible to the naked eye in many suburban skies. Parallax estimates made by the Hipparcos spacecraft put it at about 86 light-years (26 parsecs) from the Solar System, although individual Gaia Data Release 3 parallaxes place all three components at 88 light years.

::figure[src="https://upload.wikimedia.org/wikipedia/commons/2/28/9AurLightCurve.png" caption="visual band]] [[light curve]] for 9 Aurigae, adapted from Krisciunas ''et al.'' (1993)"] ::

Kevin Krisciunas and Edward Francis Guinan discovered that the star is a variable star in 1990. It is a well-studied Gamma Doradus variable, Its apparent magnitude varies from 4.93 to 5.03 over a period of 1.25804 days. For that reason it was given the variable star designation V398 Aurigae in 1995.

9 Aurigae is a multiple star system. The naked-eye component A is a single-lined spectroscopic binary. Only the signature of an F-type main sequence star can be seen in the spectrum, but the periodic doppler shift of the absorption lines demonstrates that there is a hidden companion in a 391.7-day orbit. The gravitational interaction of the two bodies produces variations in their respective motions, which is what creates the doppler shift.

Four other companions to 9 Aurigae are listed in multiple star catalogs. The closest companion is a 12th-magnitude red dwarf away. which may also be a spectroscopic binary. The most widely-separated companion is component E, a distant unrelated star.

References

References

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