SU Aurigae
A young T Tauri variable star with a protoplanetary disk.
SU Aurigae is a T Tauri-type variable star located in the constellation Auriga, approximately 500 light-years (150 parsecs) away in the Taurus-Auriga Star Forming Region. With an apparent magnitude of 9.30, it is too dim to be seen with the unaided eye. Its variability was discovered in 1907 by Henrietta Swan Leavitt.
- Constellation
- Auriga
- Apparent magnitude
- 9.30
- Distance
- ~500 light-years (150 parsecs)
- Spectral type
- G2IIIne
- Age
- ~4 million years
- Disk inclination
- 62°
- Discovery year
- 1907
Lore & Background
SU Aurigae was identified as a variable star in 1907 by Henrietta Swan Leavitt. Its spectral type of G2IIIne indicates a G-type star with an effective temperature similar to the Sun, but the luminosity class III places it in the giant star category. Despite this giant classification, the star is only about 4 million years old—a young protostar that appears luminous because it is larger and has not yet condensed to a normal main-sequence size.
The star is surrounded by a circumstellar protoplanetary disk, typical of many T Tauri stars. This disk has a high inclination of 62°, nearly perpendicular to the plane of the sky. Drops in the detected light may be caused by orbiting protoplanets or comets within the disk. SU Aurigae's proper motion and distance are similar to those of AB Aurigae, a better-known pre-main-sequence star, suggesting the two may form a very wide binary system; if not, they are at least members of the same stellar association.
Reader's Guide
SU Aurigae is significant as a T Tauri-type variable star that offers insight into the early stages of stellar evolution and planet formation. Its youth—only about 4 million years old—and its high luminosity for a G-type star illustrate the characteristics of protostars that have not yet contracted to main-sequence size. The presence of a protoplanetary disk with a high inclination of 62° provides a valuable laboratory for studying the processes that lead to planet formation, with potential transits or occultations by protoplanets or comets causing observed drops in brightness. The star's possible wide binary relationship with AB Aurigae, or at least its membership in the same stellar association, adds context to the dynamics of the Taurus-Auriga Star Forming Region. Discovered by Henrietta Swan Leavitt in 1907, SU Aurigae remains a subject of study for understanding how young stars and their disks evolve over time.
Did You Know?
- SU Aurigae is located about 500 light-years away in the Taurus-Auriga Star Forming Region.
- Its spectral type G2IIIne indicates a G-type star with a giant luminosity class, despite being only 4 million years old.
- SU Aurigae may form a very wide binary system with AB Aurigae, or is at least in the same stellar association.
Frequently Asked Questions
What is SU Aurigae?
SU Aurigae is a young T Tauri-type variable star residing in the constellation Auriga. It sits within the Taurus-Auriga Star Forming Region and hosts a protoplanetary disk tilted at roughly 62 degrees relative to our line of sight.
How far away is SU Aurigae from Earth?
The star lies approximately 500 light-years (about 150 parsecs) from us. At an apparent magnitude of 9.30, it is far too faint for naked-eye observation and requires a small telescope to spot.
Who first identified SU Aurigae as a variable star?
Henrietta Swan Leavitt discovered its variability back in 1907. Her pioneering work cataloging variable stars in the early twentieth century brought many faint objects like this one to astronomers' attention.
What is the spectral classification of SU Aurigae?
It is classified as a G2IIIne star, with the 'ne' suffix indicating emission lines typical of young, active pre-main-sequence objects. That spectral signature is fully consistent with its T Tauri designation.
How old is SU Aurigae and why does that matter to fans?
At roughly four million years of age, it is still in its infancy compared to the Sun's 4.6-billion-year lifespan. Its youth is significant because the protoplanetary disk it still harbors offers a live window into how planetary systems like our own take shape.
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