What kind of star is Mirach?
Mirach, catalogued as Beta Andromedae (β And), appears in the official constellation Andromeda. Its apparent visual magnitude is about 2.07; slight semiregular variation, while its estimated distance is about 197 light-years. Astronomers classify the object as M0 III red giant. These labels describe temperature, luminosity class or system components; they should not be read as a claim that every naked-eye point is a single isolated star.
Mirach is an evolved M-type giant with a cool, expanded atmosphere and mild brightness variability. It has exhausted core hydrogen and now radiates far more energy than the Sun despite a lower surface temperature. NGC 404 is unrelated to the star; their apparent proximity is a line-of-sight coincidence. The glare of second-magnitude Mirach makes the low-surface-brightness galaxy challenging, but also gives observers an exact acquisition point. This juxtaposition is a useful scale lesson: Mirach is hundreds of light-years away, while the galaxy lies millions of light-years beyond the Milky Way.
The coordinate pair RA 01h 09m 43.92s, Dec +35° 37′ 14.0″ fixes the object's direction on the celestial sphere for the J2000 reference epoch. Right ascension works like celestial longitude measured in hours, while declination works like latitude north or south of the celestial equator. Proper motion and improved measurements can refine catalogue positions, but these coordinates are sufficiently precise for a finder chart or planetarium search.
Mirach data at a glance
| Proper name | Mirach | Catalogue designation | Beta Andromedae (β And) |
|---|---|---|---|
| Constellation | Andromeda | Apparent magnitude | about 2.07; slight semiregular variation |
| Spectral or system type | M0 III red giant | Estimated distance | about 197 light-years |
| Right ascension (J2000) | 01h 09m 43.92s | Declination (J2000) | +35° 37′ 14.0″ |
Values are rounded for an observer-friendly overview. Consult the linked SIMBAD record for component-level identifiers, bibliography, measurement provenance and newer catalogue values.
The name Mirach
Mirach comes from Arabic mīzar, “girdle” or “waist,” identifying the star’s position at Andromeda’s hip in the classical figure.
Arabic and European atlas traditions placed Mirach at Andromeda’s girdle, and Bayer labelled it Beta Andromedae. The nearby galaxy NGC 404 was discovered by William Herschel in 1784. Its later nickname, Mirach’s Ghost, describes how the faint smudge appears to haunt the brilliant foreground star. Modern observing guides also use Mirach as the turn point in a reliable star-hop from the Great Square to Messier 31.
Modern professional catalogues retain identifiers such as the Bayer designation alongside a proper name. The International Astronomical Union standardizes which name belongs to which component—an important distinction for systems whose combined light looks like one star from Earth.
How to find Mirach
From the Great Square of Pegasus, start at Alpheratz and follow Andromeda’s chain northeast to Mirach. Then turn roughly northwest past Mu Andromedae to reach the Andromeda Galaxy. A faint galaxy, NGC 404, sits only a few arcminutes from Mirach and is nicknamed Mirach’s Ghost.
A northern star best seen on autumn evenings; visible from most populated southern latitudes as well. Visibility on a particular night still depends on latitude, season, time, horizon obstructions, weather and local light pollution. Use the interactive atlas below to check the surrounding field before observing.
Observation checklist
- Follow the Andromeda star chain northeast from Alpheratz to orange Mirach.
- For M31, move from Mirach through Mu Andromedae and continue the same distance.
- For NGC 404, use moderate power and place Mirach just outside the field to suppress glare.
- A dark, transparent sky matters more for the ghost galaxy than extreme magnification.
Interesting facts about Mirach
- Mirach is a cool red giant with mild semiregular variability.
- It is a standard star-hop marker for the Andromeda Galaxy.
- NGC 404 lies about seven arcminutes away in projection and is called Mirach’s Ghost.
- The star and NGC 404 are physically unrelated and separated by millions of light-years.
- Its traditional name refers to Andromeda’s waist or girdle.
Continue from Mirach into the night sky
Use the Andromeda constellation guide to place this star within its larger pattern. When you are ready to observe, compare dark-sky places, find a nearby observatory, or follow our practical guide to finding a star in the night sky. Symbolically registered names are kept separately in the searchable Star-Register catalogue.
Sources and further reading
Measurements are rounded for readability. Multiple systems, variable stars and distant supergiants can have component-specific or model-dependent values. Survey panels show photographic sky fields, not the physical surface of the star.