NML Cygni
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Cygnus |
| Right ascension | 20h 46m 25.54s |
| Declination | +40° 06′ 59.4″ |
| Apparent magnitude (V) | 16.60 |
| Characteristics | |
| Spectral type | M6I |
| Apparent magnitude (K) | 12.3 |
| B−V color index | +2.04 |
| Variable type | SR |
| Astrometry | |
| Proper motion (μ) |
RA: −1.55 mas/yr Dec.: −4.59 mas/yr |
| Parallax (π) | 0.620 ± 0.047mas |
| Distance | 1,610pc |
| Details | |
| Radius | 1,183 R☉ |
| Luminosity | 272,000 L☉ |
| Temperature | 3,834 K |
| Age | 8 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
NML Cygni or V1489 Cygni is a red hypergiant and one of the largest stars currently known with a radius about 1,183 times the Sun's, equal to 5.5 astronomical units. Its distance from Earth is estimated to be around 1.6 kpc, about 5,300 light-years.
NML Cygni is a part of the Cygnus OB2 association, one of the closest massive associations to the Sun, spanning nearly 2° on the sky or ∼30 pc in radius at the distance of 1.74±0.2 kpc.
NML Cygni was discovered in 1965 by Neugebauer, Martz, and Leighton who described two extremely red luminous stars, their colour being consistent with a black body temperature of 1,000 K. The name NML comes from the names of these three discoverers. The second star was briefly referred to as NML Tauri but is now known as IK Tauri, an M9 Mira variable. NML Cygni has since also been given the designation V1489 Cygni on account of the small semi-regular brightness variations, but is still most commonly referred to as NML Cygni. Its composition began to be revealed with the discovery of OH masers (1612 MHz) in 1968. Molecules like H
2O, SiO, CO, HCN, CS, SO, SO
2, and H
2S have also been detected.
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