This document provides an overview of several topics in astrophysics, including: 1. It discusses stars and their properties like mass, luminosity, temperature, and the proton-proton chain reaction. 2. It covers neutrinos and their characteristics. 3. It describes neutron stars and their properties, how they are formed in supernovas, and provides some details about Supernova 1987A. 4. It discusses pulsars and their discovery, and properties of neutron stars.

1. Basics of astrophysics

2. Stars Story
 Hydrostatic equilibrium
 Mass
 Luminosity - Temperature

4. Proton – Proton Chain
 As happens in the core of a typical main sequence star.
0.23%
99.77%
10-5%
15.08%
99.9% 0.1%
84.92%

5. Neutrino
 Leptons
 No electrical charge
 Passes through ordinary matter

6. Problem
 Determine the maximum size of rotating body with
rotation period = 0.033 second

9. Neutron Stars
 The core of a massive star in a supernova
 Chandrasekhar limit (12.5)
 Stable state
 Most SNs produce NSs -> 108 – 109 NSs in universe
 The T of a NS falls from 1012K to 1011 K in 2 seconds
 A young NS is about 106 K

10. Supernova
1987A
In LMC

11. 1987A’s Timeline
 Feb.23 7:35am, a total number of 24 neutrons detected
 Hours later the visible SN discovered
 Neutrinos and antineutrinos reached the earth
synchronously : matter, antimatter and photos react
the same against gravity
 1987A was a blue supergiant!
 Missing neutron star

12. 1987A
1987 was
discovered in
Feb., but
reached the
brightest in Mar.
AAVSO
observations

14. Rings turning on
 Months after SN
 Emission lines
 UV
 The distance: 168,000 ly

15. Neutrinos in Supernovas
 Direct observation of SNs is impossible
Dense gas surrounds SNs, and…
 Information about the inner most regions of a SN
No interaction with matter
 Delay of 1987 visible light
 First impressions in 1987

16. Some Facts
 Much of the visible light comes from the decay of
radioactive elements produced by the supernova shock
wave, and even light from the explosion itself is
scattered by dense and turbulent gases.
 The neutrino burst is expected to reach Earth before
any electromagnetic waves (SNEWS)

17. So
 Was the total energy released in a SN less than the
energy that ionized shell emits?
 99% of energy (1046 j) -> neutrinos
 Where all these neutrinos come from?

18. Urca process
 (Z-1,A) -> (Z,A) + e- + ν-e
 (Z,A) + e- -> (Z-1,A) + νe
 Two forms of beta decay
 Baryons - Leptons
 Gamow, Loosing energy (cooling), Casino Urca

19. Beta decay
Beta Minus
Beta Plus
Electron Capture

20. Pulsars
 Discovery 1967 as little green men
 Neutron stars are low in luminosity (why?)

21.  Giant atomic nucleus
 Fluid Super conductor
 Magnetic dipole radiation
 Spin periods of pulsars increase by time

24. Widescreen Test Pattern (16:9)
Aspect Ratio
Test
(Should appear
circular)
4x3
16x9