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Regulus

REGULUS (ALPHA (α) LEONIS)
BLUE STAR

Right Ascension:
10h 08m 22s

Best Seen:
3/1 - 7/1

Declination:
11º 58' 02"

Magnitude:
1.36

Computer File:
regulus

Constellation:
Leo

Actual

Compared to Sun

Distance

77 l.y.

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Actual Brightness

--

127

Surface Temperature

~ 19,000 ºF

~ 1.9

Diameter

~ 2.6 million miles

~ 3

Mass

--

4

Surface Gravity

--

--

Surface Composition (by weight)

74% hydrogen 24% helium 2% everything else

same

Spectral Type

B7 V

G2 V

Density (gram/cubic cm)

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WHAT TO LOOK FOR THROUGH THE TELESCOPE:

  1. Recommended eyepiece: 24mm or 40 mm.

  2. When people look through the telescope a bright bluish point of light should be seen.

REGULUS INFORMATION:

  1. Regulus is the 15th brightest star in the Northern Hemisphere’s night sky (22nd brightest in night sky when including Southern Hemisphere’s bright stars).

  2. Regulus is actually larger – and therefore puts off more light – than Sirius, the brightest star in the night sky. However, Sirius is brighter in the sky because it’s closer: Sirius is only 8.6 light years away.

Item
Updated Notes

Coordinates 07-17-2002
SIMBAD

Distance
07-17-2002
SIMBAD, with Hipparcos

Actual Brightness
07-17-2002
with Scott’s The Flamsteed Collection

Surface Temperature 07-17-2002
B7 temp close to 10,000K: assumed 11,000 K

Diameter
07-17-2002
based on assumed 11,000K temp

Mass
07-17-2002
mass-lum rel: L = M3.5

Surface Composition 01-06-2003
OK for all stars

Spectral Type
–

Other Information
07-17-2002

07-17-2002

07-17-2002

07-17-2002

07-22-2002

  1. previous mass listing: 5 times our Sun – BUT could find no evidence
  2. previous gravity: 15.5 times our Sun – BUT could find no evidence
  3. previously: “2a. Has a companion star 440 billion miles away, or about 4,600 Earth-Sun distance (177"). 2b. Companion’s brightness: .5 Sun’s brightness (or 1/300 Regulus’ brightness)” – BUT could find no evidence
  4. previous density: 0.04 – BUT how know this?
  5. previous: 21st brightest star – BUT with Hipparcos, these ‘ranks”

Composition 7/30/13 Changed to 70% / 24% / 2%