1. SUN;
SO CLOSE, SO FAR
ACCORDING TO
“Fundamental Astronomy” BY
Dr. Hannu Karttunen, Dr. Pekka Kröger, Dr. Heikki Oja, Dr. Markku Poutanen, Dr. Karl Johan
Donner
1
astronaut.com

2. Introduction
- The nearest star to us
- The importance of
studding of the sun in
astronomy
Our present picture of the
Sun, is based both on
observations and on
theoretical calculations.
2
weknowyourdreams.com
𝑺𝒐𝒎𝒆 𝒐𝒃𝒔𝒆𝒓𝒗𝒂𝒕𝒊𝒐𝒏𝒔 ≠ 𝑻𝒉𝒆 𝒕𝒉𝒆𝒐𝒓𝒆𝒕𝒊𝒄𝒂𝒍 𝒔𝒐𝒍𝒂𝒓 𝒎𝒐𝒅𝒆𝒍𝒔

3. Internal Structure
Mass 𝑚 = 𝑀𝑆 = 1.989 × 1030
𝑘𝑔
Radius 𝑅 = 𝑅 𝑆 = 6.960 × 108
𝑚
Mean density 𝜌 = 1409 𝑘𝑔 𝑚3
Central density 𝜌𝑐 = 1.6 × 105
𝑘𝑔 𝑚3
Luminosity 𝐿 = 𝐿 𝑆 = 3.9 × 1026
𝑊
Effective temp. 𝑇𝑒 = 5785 𝐾
Central temp. 𝑇𝑐 = 1.5 × 107
𝐾
Spectral class G2 V
Color indices 𝐵 − 𝑉 = 0.62
𝑈 − 𝐵 = 0.10
Rotational period
at the equator 25 𝑑
at latitude 60˚ 29 𝑑
The Sun is a typical main
sequence star.
3

4. 4
99% of the solar energy is
produced within a quarter
of the solar radius.
The Sun produces energy
at the rate of 4 × 1026 𝑊.
𝑀𝑆
𝑀 𝐸
= 330000
The Sun formed about 5
billion years ago.
About 5% of the hydrogen
in the Sun has been turned
into helium.
The solar model

5. 5
The radiative central part
of the Sun extends to
about 70% of the radius.
The Sun has a convective
envelope.

6. 6
The rotation rate of the Sun
inferred from helioseismological
observations.
The Sun's rotation rate
decreases with increasing
latitude, So The regions of the
Sun near its equator rotate
once every 25 days and its
rotation rate is slowest near its
poles. At its poles the Sun
rotates once every 36 days!
Helioseismology is the study of the propagation of wave
oscillations, particularly acoustic pressure waves, in the Sun.

7. The Solar Neutrino Problem!
The standard model is the
name given in the 1970s to
a theory of fundamental
particles and how they
interact.
7

8. 8 ppI:
1 1
1
𝐻 + 1
1
𝐻 → 2
2
𝐻 + 𝑒+
+ 𝜈 𝑒
1
1
𝐻 + 1
1
𝐻 + 𝑒− → 2
2
𝐻 + 𝜈 𝑒
2 2
2
𝐻 + 1
1
𝐻 → 2
3
𝐻𝑒 + γ
3 2
3
𝐻𝑒 + 2
3
𝐻𝑒 → 2
4
𝐻𝑒 + 21
1
𝐻
ppII:
3 2
3
𝐻𝑒 + 2
4
𝐻𝑒 → 4
7
𝐵𝑒 + γ
4 4
7
𝐵𝑒 + 𝑒− → 3
7
𝐿𝑖 + 𝜈 𝑒
5 3
7
𝐿𝑖 + 1
1
𝐻 → 2
4
𝐻𝑒 + 2
4
𝐻𝑒
ppIII:
3 2
3
𝐻𝑒 + 2
4
𝐻𝑒 → 4
7
𝐵𝑒 + γ
4 4
7
𝐵𝑒 + 1
1
𝐻 → 5
8
𝐵 + γ
5 5
8
𝐵 → 4
8
𝐵𝑒 + 𝑒+ + 𝜈 𝑒
6 4
8
𝐵 → 2
4
𝐻𝑒 + 2
4
𝐻𝑒
When neutrinos from the
Sun were first observed in
the 1970’s, their number
was found to be only
about a third of what was
predicted. This
disagreement is called the
solar neutrino problem.
Perhaps the most popular
explanation for the solar
neutrino problem was
based on neutrino
oscillations.

9. 9 In 2001 results were
announced from
experiments in Canada
and Japan that measured
both the number of
electron neutrinos and the
total number of neutrinos
arriving from the Sun.
This result proved the existence of
neutrino oscillations turning some of
the electron neutrinos produced in the
center of the sun into other kinds.

10. The Solar Rotation
Sun is rotating with a
rotational period of about
27 days.
The angular velocity is
usually written
Ω = 𝐴 − 𝐵 sin2 𝜓
where ψ is the latitude with
respect to the equator. The
measured values of the
coefficients are A = 14.5
and
B = 2.9 degrees/day.
10

11. Created by:
Milad Hajebrahimi
11