Basic solar parameters and information

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The concept of an internationally standardized system of units (astronomical units or astronomical constants) is one of the most fundamental in experimental science. Here you can found some basic parameters and information of the Sun. This information is in accordance by XVIth General Assembly, Grenoble, France, 1976 (pdf) of International Astronomical Union.

 

Sun as a star

The Sun is a star of a yellow dwarf type with spectral class of G2V. G2 means that it has a surface temperature of approximately 5,770 K (5,500 °C) giving it a white color that often, because of atmospheric scattering, appears yellow when seen from the surface of the Earth. V means that it belongs to the stellar population of the main sequence in the “color-magnitude“stellar diagram.
The Sun orbits the center of the Milky Way galaxy at a distance of approximately 30 000 light years from the galactic center, moving generally in the direction of Cygnus constellation and completing one revolution in about 250 million years (one Galactic year). Its orbital speed was thought to be 220±20 km/s, but a new estimation gives about 250 km/s. Except that basic motion, the Sun moves with a speed of 20 km/s in a direction to the Hercules constellation, according to the relatively close stars (up to 200 parsecs).
 
 
Basic parameters of the Sun
 
As a star
Age:                                  4.5 x 109 years
Spectral type:                  G2V
Visual magnitude:          -26.74
Absolute magnitude:     +4.83
Effective temperature:   5770 К
 
 
Physical parameters
Radius (R):                            695.5 x 106 m (1R=0.004649 AU; ~109 radii of Earth; Earth radii = 6371km)
Surface area:                            609 x 1016 m2
Mass (M):                              1.989 x 1030 kg (332 946 masses of Earth)
Mean density:                           1.409 g/cm3 (0.256 of mean density of Earth)
Central density:                        98 g/cm3
Luminosity:                               3.86 x 1033 erg/s  (3.86 x 1026 W)
Angular velocity of rotation (at latitude 16º):               2.865 x 10-6 rad/s
Linear velocity of rotation for the point at equator:    2.025 km/s
Acceleration at the solar surface (photosphere):     274 m/s2 (28 gÅ)
Escape velocity at the solar surface:                          617.7 км/с2
 
 
Sun’s parameters visible from the Earth
Distance from Earth
Mean (1 astronomical unit-AU):        149.6 x 106 km (measured by telemetry method on 2009 1AU* = 149 597 870 700m; 215.1R)
In perihelium:                                       147.1 x 106 km (147 098 074 km or 0.9832898912 AU)
In aphelium:                                         152.1 x 106 km (152 097 701 km or 1.0167103335 AU)
 
Apparent radius
Apparent radius at 1 AU:                                                                             959.63”
Apparent radius plus irradiation (for the disc edge observation):      961.2”
Flatness (difference between equatorial and polar radius):               0.05”?
 
Apparent diameter
At 1 AU:             31’ 59.26”
In perihelion:   32’ 31.89”
In aphelion:      31’ 27.70”
 
Rotation period of the Sun(at latitude of 16o)
Sidereal rotation:          25.38 days or 14,184 degree/day
Sinodic rotation:           27.28 days or 13,199 degree/day (Carrington rotation)
 
Inclination of Sun’s equator plane to the ecliptic plane: 7° 15’
 
1’ of arc at 1 AU:        43 520 km
1” of arc at 1 AU:             725.3 km
 
 
Sun Basic Facts
Age
At least 4.5 x 109 years in present state
Chemical composition of photosphere ( by mass, in %)
 
Hydrogen
73.46
Helium
24.85
Oxygen
0.77
Carbon
0.29
Iron
0.16
Neon
0.12
Nitrogen
0.09
Silicon
0.07
Magnesium
0.05
Sulfur
0.04
Other
0.10
 
Density (water=1000):
 
Mean density of entire Sun
1410 kg/m3
Interior (center of Sun)
160000 kg/m3
Surface (photosphere)
10–6 kg/m3
Chromosphere
10–9 kg/m3
Low corona
10–13 kg/m3
Sea level atmosphere of Earth (for comparison)
1.2 kg/m3
 
Diameter (at the Photosphere)
 
1.39x106 km (109 times the diameter of Earth and 9.75 times the diameter of Jupiter
Distance
 
mean distance from Earth
149 597 870 700m (~149.6 x106 km = 1 AU)
Variation in distance through the year
±1.5 percent
 
Magnetic field strengths for typical features:
 
Sunspots
0.3 tesla                    (3000 Gauss)
Polar field
10–4 tesla                 (1÷2 Gauss)
Bright, chromospheric network
0.0025 tesla             (25 Gauss)
Ephemeris (unipolar) active regions
0.0020 tesla             (20 Gauss)
Chromospheric plages
0.02 tesla                  (200 Gauss)
Prominences
10–3 to 10–2 tesla   (10÷100 Gauss)
Earth (for comparison)
30÷60x10–6 tesla    (0.3÷0.6 Gauss)
Mass
1.99x1030 kg (or 333 000 times the mass of Earth)
Differential rotation (as seen from Earth):
 
Of solar equator
26.8 days
At solar latitude 30o
28.2 days
At solar latitude 60o
30.8 days
At solar latitude 75o
31.8 days
 
Solar radiation:
 
Entire Sun
3.83x1023 kW
Unit area of surface of Sun
6.29x104 kW/m2
Received at top of Earth’s atmosphere
 
Received at the Earth’s surface (for Bulgaria)
1366 W/m2 (from 1,412 W/m2 in early January to 1,321 W/m2 in early July)
 ≈175 W/m2
 
Surface brightness of the Sun (photosphere):
 
Compared to full Moon
398 000 times
Compared to inner corona
300 000 times
Compared to outer corona
1010 times
Compared to daytime sky on Pikes Peak
100 000 times
Compared to daytime sky at Orange, N.J.
1000 times
 
Temperature:
 
Interior (center)
15 000 000 K
Surface (photosphere)
6050 K
Sunspot umbra (typical)
4240 K
Penumbra (typical)
5680 K
Chromosphere
4300 to 50 000 K
Corona
800 000 to 3 000 000 K
Volume
1.41x1027 m3 (or 1.3 million times the volume of Earth)
 

 

 

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