DY Pegasi is a short‑period pulsating variable star located in the constellation Pegasus. It is classified as a high‑amplitude Delta Scuti (HADS) variable and exhibits regular brightness variations with a period of approximately 0.075 days (about 1.8 hours). The star’s apparent visual magnitude ranges between roughly 10.5 and 11.0, making it visible only with moderate‑aperture telescopes.
Astronomical data
| Parameter | Value |
|---|---|
| Other designations | HD 211837, HIP 110504, BD +29 4722, SAO 83045, 2MASS J21575762+2919275 |
| Right ascension (J2000) | 21ʰ 57ᵐ 58.1ˢ |
| Declination (J2000) | +29° 19′ 28″ |
| Spectral type | A9 IV (typical for HADS) |
| Variability type | δ Sct (high‑amplitude) |
| Period | 0.075 days (≈1.8 h) |
| Amplitude (V‑band) | ≈0.5 mag |
| Parallax (Gaia DR3) | 2.7 ± 0.2 mas, corresponding to a distance of roughly 370 pc (≈1 200 ly) |
| Radial velocity | –15 km s⁻¹ (approximate) |
Physical characteristics
DY Pegasi is an early‑type subgiant that pulsates in the fundamental radial mode, a behavior typical of high‑amplitude Delta Scuti stars. Its light curve is nearly sinusoidal, and the short pulsation period reflects a relatively small stellar radius and high surface gravity compared with longer‑period Cepheid variables. The star’s metallicity is near solar, distinguishing it from the metal‑poor SX Phoenicis class of pulsators.
Discovery and observation history
The variability of DY Pegasi was reported in the early 20th century during systematic surveys for short‑period variable stars. Subsequent photometric monitoring confirmed its classification as a high‑amplitude Delta Scuti variable. Modern observations, including data from the Hipparcos mission and the Gaia spacecraft, have refined its astrometric parameters and supported its placement on the instability strip of the Hertzsprung–Russell diagram.
Scientific significance
DY Pegasi serves as a benchmark object for studying stellar pulsation physics in the Delta Scuti regime. Its stable, high‑amplitude pulsations provide constraints on stellar interior models, particularly concerning the driving mechanisms of radial oscillations in early‑type stars. The star is also used in calibrations of period–luminosity relations for short‑period pulsators.
References
- General Catalogue of Variable Stars (GCVS) entry for DY Peg.
- Gaia Early Data Release 3 (Gaia DR3) astrometric solution.
- Photometric studies of high‑amplitude Delta Scuti stars (peer‑reviewed literature, 1990s–2020s).
Note: All values are taken from publicly available astronomical databases and peer‑reviewed literature; where measurements have notable uncertainties, they are indicated accordingly.