Stellar Astronomy

Code:

AST232

Acronym:

AST232

Keywords
Classification	Keyword
OFICIAL	Astronomy

Instance: 2013/2014 - 2S

Active?	Yes
Web Page:	https://moodle.up.pt/course/view.php?id=317
Responsible unit:	Department of Physics and Astronomy
Course/CS Responsible:	First Degree in Astronomy

Cycles of Study/Courses

Acronym	No. of Students	Study Plan	Curricular Years	Credits UCN	Credits ECTS	Contact hours	Total Time
L:AST	11	Plano de Estudos a partir de 2008	2	-	7,5	-
L:B	0	Plano de estudos a partir de 2008	3	-	7,5	-
L:CC	0	Plano de estudos de 2008 até 2013/14	3	-	7,5	-
L:F	2	Plano de estudos a partir de 2008	2	-	7,5	-
L:G	0	P.E - estudantes com 1ª matricula anterior a 09/10	3	-	7,5	-
		P.E - estudantes com 1ª matricula em 09/10	3	-	7,5	-
L:M	0	Plano de estudos a partir de 2009	3	-	7,5	-
L:Q	0	Plano de estudos Oficial	3	-	7,5	-

Teaching language

Portuguese

Objectives

The course aims to basic training in stellar astronomy, both in terms of concepts and physical/mathematical tools. The approach is at an intermediate level where, together with the clarification of concepts, emphasis is given to its foundations in formal terms.

Learning outcomes and competences

Understanding of global concepts in stellar astronomy and ability to relate them. Skills in the description of physical phenomena which occur in stars (interior and atmospheres) and during the star formation.

Working method

Presencial

Program

1. Introductory Concepts Review of concepts related to the theory of radiation, blackbody radiation, systems of magnitude, color index, spectral classification, Hertzsprung-Russell diagram. Atmospheric absorption. Seeing. Interstellar absorption (reddening). Variable stars.

2. Celestial Mechanics Two body systems bodies. Derivation of Kepler's laws and determination of orbits. Binary stars and determination of stellar masses. The mass-luminosity relation. The virial theorem.

3. Stellar Atmospheres The Boltzmann equation for the thermal excitation. The Saha equation for thermal ionization. Examples. The radiative transport equation and its moments equations. Application to stellar atmospheres: llimb darkening. Opacity of stellar material. Kramers absorption. Structure of spectral lines. Equivalent width and half width-height. Broadening of spectral lines. Curve of growth analysis.

4. Stellar Interiors Structure equations (review). The equation of state, ideal gas, polytropic processes. The radiation pressure. Equation of state for a completely degenerated electron gas. Convective instability, Schwarzschild criterion and causes of instability. Convection in cool stars and hot stars. Energy sources: Hydrogen fusiin (PP, CNO) and helium fusion (3 alpha). Examples of models for solar-type stars and hot stars. 5. Formation and Stellar Evolution Molecular clouds. The gravitational instability and the Jeans mass. Fragmentation of the cloud. Homologous collapse. Free-fall time. The formation of the protostar. The Virial Theorem for a system in hydrostatic equilibrium. Kelvin-Helmholtz time. Evolution of the star towards the main sequence: the Hayashi track. Evolution of stars during and after the main sequence for massive stars and low mass stars. Final stages of evolution: planetary nebulae, white dwarfs and the Chandrasekhar mass limit, type II supernovae, neutron stars and limiting mass.

Mandatory literature

Carroll, W.B., Ostlie, D.A.; An Introduction to Modern Astrophysics, Addison Wesley, 1995. ISBN: 0201547309

Complementary Bibliography

Böhm-Vitense, E.; Introduction to Stellar Astrophysics. Vol 1: Basic Stellar Observations and Data, Cambridge University Press, 1989. ISBN: 0521348692
Böhm-Vitense, E; Introduction to Stellar Astrophysics. Vol 2: Stellar Atmospheres, Cambridge University Press, 1989. ISBN: 0521348706
Böhm-Vitense, E; Introduction to Stellar Astrophysics. Vol 3: Stellar Structure and Evolution, Cambridge University Press, 1992. ISBN: 0521348714

Teaching methods and learning activities

Expository methods in theoretical lectures (T). In theoretical-practical classes (TP) resolution of exercises by the students.

keywords

Physical sciences > Astronomy > Astrophysics

Evaluation Type

Distributed evaluation without final exam

Assessment Components

designation	Weight (%)
Teste	100,00
Total:	100,00

Amount of time allocated to each course unit

designation	Time (hours)
Estudo autónomo	132,00
Frequência das aulas	70,00
Total:	202,00

Eligibility for exams

The student has frequency to the course if he/she misses no more than 1/3 of the planned theoretical-practical classes (TP's).

Calculation formula of final grade

Continuous evaluation with 2 assessment tests. The final mark is the average of the assessment tests. Minimun mark of 35% in each test.

Evaluation by final exam: If the student chooses not to undergo continuous evaluation he/she must inform the lecturer (by email) until the normal exam date.In this case the final mark is the exam mark.

Classification improvement

It is possible to improve grades only through the resit exam (without consultation, marked up to 20).