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Sirius

SIRIUS (ALPHA (α) CANIS MAJORIS)
BLUE STAR

Right Ascension:
6h 45m 09s

Best Seen:
2/15 - 4/15

Declination:
-16º 42' 58"

Magnitude:
-1.42

Computer File:
sirius

Constellation:
Canis Major

Actual

Compared to Sun

Distance

8.60 l.y.

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Actual Brightness

--

21

Surface Temperature

~ 18,000 ºF

~ 1.8

Diameter

~ 1.2 million miles

~ 1.4

Mass

--

~ 2

Surface Gravity

--

--

Surface Composition (by mass)

74% hydrogen 24% helium 2% everything else

same

Spectral Type

A1 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.

SIRIUS INFORMATION:

  1. Sirius is the brightest star in the night-time sky (considering bright stars in both the Northern and Southern Hemisphere).

  2. Sirius is the 6th nearest known star.

  3. Sirius also has a white dwarf companion.

Period: 50 years

Separation
highly elliptical orbit, so separation varies between ~744 million miles to ~2.88 billion miles (~8 to ~31 times the Earth-Sun distance)

Mass:
~equal to sun

Diameter:
7,300 miles

Density:
~90,000 times the sun’s density (125,000 times that of water or 2.25 tons/in3)

Luminosity: ~1/400 of the sun’s

Temperature:
44,500 ºF (25,000K)

Spectral Type:
A2-5 VII

  1. Over many, many years, the motion of Sirius through the sky can be detected. In 1718, Sir Edmund Halley was the first to reveal that stars were not permanent fixtures in the sky by detecting the motion of Sirius.

Item
Updated Notes

Coordinates 07-17-2002
SIMBAD

Magnitude
07-17-2002
with Scott’s The Flamsteed Collection

Distance
07-22-2002
with The Flamsteed Collection

Actual Brightness
07-22-2002
with The Flamsteed Collection

Surface Temperature 07-22-2002
assume A type stars’ top temp (A0 stars?) of 10,000K

Diameter
07-22-2002
assume temp 10,000K

Mass
11-20-2002
http://www.astro.uiuc.edu/~kaler/sow/sirius.html and http://chandra.harvard.edu/photo/cycle1/0065/

Surface Gravity

Surface Composition 01-06-2003
OK for all stars

Spectral type
07-22-2002
SIMBAD

Other Information
07-22-2002

07-22-2002

08-30-2002
1. previous: 5th nearest known star – BUT with Hipparcos, 6th nearest 2. previous: “Sirius also has a white dwarf companion: Period: 50 years Separation: 22 billion miles (24 times the Earth-Sun distance) Mass: ~equal to sun
Diameter: 16,000 miles
Density: 90,000 times the sun’s density (125,000 times that of water or 2.25 tons/in3) Luminosity: 1/400 of the sun’s
Temperature: 15,000 to 16,000 oF Spectral Type: A5" – BUT can only find current info based on:
http://www.solstation.com/stars/siriu s2.htm and http://antwrp.gsfc.na sa.gov/apod/ap001006.html 3. Item 4 from Scott’s Starlist 2000

Changed composition
7/30/13 Changed from: 70% hydrogen 28% helium 2% everything else to 74% hydrogen
24% helium 2% everything else