Haggart Astronomical Observatory
Clackamas Community College
Oregon City, OR

503-657-6958 x5665 ("LOOK")

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Bright Stars

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MAGNITUDE:
Stargazers rank stars by magnitude - their apparent brightness in the night sky.
A star's magnitude depends on its luminosity (light given off) and distance.
The brightest stars are 1st magnitude; the faintest naked-eye stars are 5th or 6th magnitude.

How Many Stars Can We See?

Here's a rough count by magnitude, for the entire celestial sphere.
At Haggart, 15 first-magnitude stars are visible; these are our "signposts" for locating other objects.
In our urban skies, 4th & 5th magnitude stars are often too dim for the unaided eye.

(from Rey, The Stars: A New Way To See Them)

Magnitude # Stars
0-1 21
2 50
3 150
4 600
5 1500

BRIGHT STARS (mag. 1 or 0) THROUGH THE YEAR
  Star Constellation J   F  M  A  M  J  J  A  S  O  N  D 
"Winter Hexagon' Betelgeuse Orion X X X - - - - - - - - X
Sirius Canis Major X X X - - - - - - - - -
Procyon Canis Minor X X X X X - - - - - - X
Pollux Gemini X X X X - - - - - - X X
Capella Auriga X X X X X - - - X X X X
Aldebaran Taurus X X X - - - - - X X X X
Rigel Orion X X X - - - - - - - - X
"Summer Triangle" Vega Lyra - - - X X X X X X X X X
Deneb Cygnus X - - - X X X X X X X X
Altair Aquila - - - - X X X X X X X -
Other Antares Scorpio - - - - X X X X - - - -
Arcturus Bootes - - X X X X X X X X - -
Spica Virgo - - X X X X X - - - - -
Fomalhaut Piscis Austrinus - - - - - - - - X X X X
Regulus Leo X X X X X X - - - - - -

First-Magnitude Stars Visible at Our Latitude - Data         
Mass: M=1 solar mass         m.s.=main sequence ("ordinary" star, in hydrogen-burning stage)       
Name Mag. Dist.
(ly)
Mass
(M)
Spectral
Class		 Notes
Sirius
 -1.46 9 2M A: White m.s.

aka "Dog Star" (Orion's dog)
lit. "scorching" (rises with the sun in the hottest months)

Arcturus
 -0.04 37 2M K: orange giant lit. "bear guard" (seems to chase the Big & Little Bears around the sky)
Vega
 0.03 25 1.5M A: white m.s. "the swooping one " - an eagle
Capella
 0.08 42 2.7M G: yellow giant
"she-goat"; close double star
Rigel 0.12 773 17M B: blue m.s. "foot" (Orion's)
Procyon
 0.38 11 1.5M F: white m.s.
 "before the dog" (rises before Sirius)
Betelgeuse
 0.50 522 15M M: Red supergiant "armpit" (Orion's)
Altair
 0.77 17 1.7M A: white m.s.
 "flying one" - Altair is in Aquila, the Eagle
Aldebaran
 0.85 65 1M K: orange giant
 "follower" (follows the Pleiades star-cluster)
Antares 0.96 604 10M M: red supergiant "rival of Ares" - e.g., rivalling Mars (Ares in Greek) in color
Spica
 0.98 262 9M B: blue-white m.s.
 "ear of wheat" - which Virgo is holding
very tight double
Pollux
 1.14 34 4M K: orange giant "much wine"
Fomalhaut
 1.16 25 2.3M A: white m.s.
 "mouth of the fish" - in Piscis Australinus, the Southern Fish
Deneb
 1.25 1467 20M A: white supergiant "The Tail" - of Cygnus the Swan
Regulus 1.35 77 3.5M B: blue-white m.s. "prince"
Not visible in the northern hemisphere: Canopus (Carina, -0.72), Alpha Centauri (0.0), Achernar (Eridanus, 0.46), Beta Centauri (0.61), Alpha Crucis (1.41), Beta Crucis (1.25)
Note: data for stellar distances and mass vary considerably in different sources!

In order to be so bright in our night sky, these 15 first-magnitude stars are all either relatively close or unusually bright. Many of them are "giants" - stars in a late stage of their evolution, swollen to a very large surface area and emitting a great deal of light. Those that are still in the long hydrogen-burning stage of life (the "main sequence") are either very massive or nearby.

Main-sequence Stars (burning hydrogen to helium) Evolved (dying) Giant Stars -
burning helium to carbon and oxygen
  • B ("blue giant"): Rigel, Spica, Regulus
  • A (white): Sirius, Vega, Altair, Fomalhaut
  • F (yellow-white): Procyon
  • A (white): Deneb
  • G (yellow): Capella
  • K (orange): Arcturus, Aldebaran, Pollux
  • M (red): Betelgeuse, Antares
 

Sources:

Star data - magnitude, distance, star class
      Pasachoff, Jay M. and Alex Filippenko. The Cosmos: Astronomy in the New Millenium, 2nd ed., Thomson, 2004.

Star data - mass (when given) are from:
     Kaler, James B. The Hundred Greatest Stars. New York: Copernicus, 2002.
     Moore, Patrick. The Observer's Year. Springer, 1998.
     Chaisson, Eric and Steve McMillan. Astronomy Today, 4th ed. Prentice-Hall, 2002.

Additional star data & information:
      SolStation.com: Nearby Stars site (www.solstation.com/stars.htm)

Visibility through the year; number of visible stars by magnitude:
      Rey, H.A. The Stars: a New Way to See Them.

Names: http://www.astro.wisc.edu/~dolan/constellations/extra/brightest.html, SEDS

 

 

 

 

 

klh 6/21/03