Mirach – Beta Andromedae & NGC 404 Mirach’s Ghost!
Captured on 10-01-2021 with a TPO 12 inch F4 telescope/Bisque ME Mount & HAP Modified Canon 6D DSLR Camera, ISO 800, 10 minute exposure.
Beta Andromedae, Latinized from β Andromedae, and officially named Mirach is a prominent star in the northern constellation of Andromeda.
It is northeast of the Great Square of Pegasus and is potentially visible to all observers north of latitude 54° S.
It is commonly used by stargazers to find the Andromeda Galaxy.
NGC 404 is a small 11.7 magnitude elliptical Galaxy also known as Mirach’s Ghost, visually it is seven arc minutes away
from Mirach. Although visible in the same FOV as Mirach, NGC 404 is actually located about 10 million light years away, well beyond Mirach.
It was discovered by Sir William Herschel in 1784, and is visible through small telescopes.
NGC 404 lies just beyond the Local Group and does not appear gravitationally bound to it.
In the telescope eyepiece it helps to place Mirach just outside the edge of the FOV, so you can easily see the fainter glow of NGC 404.
Mirach has an average apparent visual magnitude of 2.05, making it the brightest star in the constellation.
The luminosity varies slightly from magnitude +2.01 to +2.10.
Based upon parallax measurements, it is roughly 197 light-years (60 parsecs) from the Sun.
Its apparent magnitude is reduced by 0.06 by extinction due to gas and dust along the line of sight.
Beta Andromedae is a single red giant with a stellar classification of M0 III, and is currently on the asymptotic giant branch of its evolution.
Since 1943 the spectrum of this star has been one of the stable anchor points by which other stars are classified.
It is suspected of being a semiregular variable star whose apparent visual magnitude varies from +2.01 to +2.10.
At this stage of the star’s evolution, the outer envelope has expanded to around 100 times the size of the Sun.
It is radiating 1,995 times the luminosity of the Sun at an effective temperature of 3,842 K.