28 Andromedae
A Delta Scuti variable star in Andromeda, candidate triple system.
28 Andromedae, also known by its variable star designation GN Andromedae, is a Delta Scuti variable star located in the constellation Andromeda. It has an apparent magnitude of 5.214, with brightness variations of less than 0.1 magnitudes. This bluish-white star is an A-type giant, situated roughly 199 light-years (61 parsecs) away according to Hipparcos parallax measurements, and it is moving toward the Solar System at a velocity of 10.30 km/s.
The system is a candidate triple star: two fainter companions share a common proper motion with the primary, though their orbital parameters remain unknown. The secondary and tertiary components have masses of 0.71 and 0.14 solar masses, respectively. As a Delta Scuti variable, 28 Andromedae A exhibits small luminosity changes on timescales under a day due to stellar pulsation. Evidence suggests two pulsation cycles lasting 5,014 and 5,900 seconds, but the amplitude of these variations is not constant over time, and the pulsation modes are non-radial.
- Flamsteed designation
- 28 Andromedae
- Variable star name
- GN Andromedae
- Apparent magnitude
- 5.214
- Magnitude variation
- less than 0.1 magnitudes
- Spectral type
- A-type giant
- Distance
- about 199 light years (61 parsecs)
- Radial velocity
- 10.30 km/s (towards the solar system)
- Pulsation periods
- 5,014 seconds and 5,900 seconds
Lore & Background
28 Andromedae is an A-type giant star, colored bluish-white. Parallax estimates from the Hipparcos spacecraft place it at a distance of about 199 light years (61 parsecs). It is moving towards the solar system at a velocity of 10.30 km/s. Two stars near 28 Andromedae share a common proper motion with the primary, making it a candidate triple system, though the orbital parameters are currently unknown. The second and third components have masses of 0.71 M☉ and 0.14 M☉ respectively.
Reader's Guide
28 Andromedae is significant as a Delta Scuti variable, a class of pulsating stars that exhibit small luminosity variations on timescales less than a day. Its variability cycle shows evidence for two periodic cycles of 5,014 and 5,900 seconds, though the amplitude variations are not constant in time and the pulsation modes are non-radial. The star's status as a candidate triple system adds to its interest, as the two companion stars share a common proper motion, suggesting a physical association. However, the orbital parameters remain unknown, leaving the system's dynamics unresolved. The star's proximity, at about 199 light years, and its small magnitude variation make it a useful target for studying Delta Scuti pulsations and multiple-star systems. Its legacy lies in contributing to the understanding of stellar pulsation and multiplicity, though further observations are needed to clarify its orbital configuration.
Did You Know?
- 28 Andromedae varies in brightness by less than 0.1 magnitudes.
- It has two pulsation cycles of 5,014 and 5,900 seconds.
- Two companion stars share a common proper motion with 28 Andromedae, making it a candidate triple system.
- The star is moving towards the solar system at 10.30 km/s.
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