| Home > Stars > Red > Red Supergiant Stars > Alpha Orionis |
Alpha (α) Orionis
Betelgeuse
Red Supergiant Star
| Right Ascension | 5h 53m 48s | Best Seen | 1/1 - 4/15 |
| Declination | 7° 24' 14" | Magnitude | 0.45 |
| Constellation | Orion | ||
| Actual | Compared to Sun | |
| Distance | ~427 ly | -- |
| Actual Brightness | -- | 8,900 |
| Surface Temperature | ~5,600 °F | ~0.56 |
| Diameter | ~800 million miles | ~930 |
| Mass | -- | 20 |
| Surface Gravity | -- | -- |
| Surface Composition (by mass) | 74% hydrogen 24% helium 2% everything else |
same |
| Spectral Type | M2 Ib | G2 V |
| Density (gram/cubic cm) | -- | -- |
What To Look For Through The Telescope
-
Recommended eyepiece: 24mm or 40 mm.
-
When people look through the telescope a bright reddish-orange point of light should be seen.
Betelgeuse Information:
-
Betelgeuse is the 7th brightest star in the Northern Hemisphere’s night sky (9th brightest if including the Southern Hemisphere’s bright stars).
-
An irregularly pulsating red supergiant – its diameter may vary as much as 60% during the whole cycle.
-
Note the size of this star: if Betelgeuse were placed in our solar system at our sun’s position, Mercury, Venus, Earth, Mars, and maybe even Jupiter would be inside Betelgeuse!
-
This is the biggest star seen from Earth, and probably one of the biggest anywhere.
| Home > Stars > Red > Red Supergiant Stars > Alpha Orionis | top |
References
| Item | Updated | Notes |
| Coordinates | 2003-01-06 | tweaked a bit |
| Magnitude | 2003-01-06 | previously 0.70 – BUT SIMBAD says 0.58, and Flamsteed says 0.45 |
| Distance | 2003-01-06 | previously 520 – BUT now OK with Scott’s The Flamsteed Collection and SIMBAD |
| Actual Brightness | 2003-01-06 | previously 14,000 – BUT now OK with Flamsteed |
| Surface Temperature | 2003-01-06 | can’t find direct support, but OK with numbers given in Flamsteed |
| Diameter | 2003-01-06 | previously:480-800 million miles / 550-920 times sun – BUT think it’s safe to say over 800 million - beyond Jupiter’s orbit - like said in http://antwrp.gsfc.nasa.gov/apod/ap970216.html |
| Mass | 2003-01-06 | can find no support, but sounds good |
| Surface Gravity | -- | |
| Surface Composition | 2003-01-06 | OK for all stars |
| Spectral Type | 2003-01-06 | OK with Scott’s Flamsteed |
| Density | 2003-01-06 | previously: <10-6 – BUT can find no support for this |
| Other Information | 2003-01-06 | OK |