Stellar Formation and Circum-Estelar Medium

Code:

AST4004

Acronym:

AST4004

Keywords
Classification	Keyword
OFICIAL	Astronomy

Instance: 2021/2022 - 2S

Active?	Yes
Responsible unit:	Department of Physics and Astronomy
Course/CS Responsible:	Master in Astronomy and Astrophysics

Cycles of Study/Courses

Acronym	No. of Students	Study Plan	Curricular Years	Credits UCN	Credits ECTS	Contact hours	Total Time
M:A_ASTR	8	Plano de Estudos oficial desde_2013/14	1	-	6	42	162

Teaching language

Suitable for English-speaking students

Objectives

The processes associated with the formation and the early evolution of stars are introduced. The period in analysis includes the molecular clouds formation, the formation of the proto-star and the pre-main-sequence evolution before the star reaches the main sequence. Complementing the theoretical part, we present observational examples of the different stages of evolution of a young star.

Learning outcomes and competences

At the end, the student will have a global view of the theories of star formation and pre-main sequence stellar evolution. The student will also have a global view over the observational component that is used for the study of molecular clouds, protostars and circumstellar medium.

Working method

Presencial

Program

I - Star Formation in our Galaxy

1. Overview

1. Stellar Nurseries
2. Stars and their evolution
3. The Galactic context

2. Interstellar Medium (ISM)

1. Galactic Gas
2. Phases of the ISM
3. Insterstellar Dust - Extinsion/Emission - Propreties of the grains

3. Molecular Clouds

1. Giant Molecular Clouds
2. Virial Theorem Analysis
3. Dense Cores

4. Young Stellar Systems

1. Embebed Clusters
2. The Initial Mass Function

II - Physical Processes in Molecular Clouds

1. Introduction to Radiative Transfer

2. Molecular Transitions

1. Interstellar Molecules
2. Hydrogen (H2)
3. Carbon-Monoxide (CO)
4. Applications of CO

3. Heating and Cooling

1. Cosmic Rays
2. Interstellar Radiation
3. Cooling by Atoms, Molecules and Dust

4. Cloud Thermal Structure

1. The Buildup of Molecules
2. The Molecular Interior

III - From Clouds to Stars

1. Cloud Equilibrium and Stability

1. Isothermal Spheres and the Jeans Mass
2. Magnetostatic Configurations

2. The Collapse of Dense Cores

1. Ambipolar Diffusion
2. Inside-Out Collapse

3. Protostars

1. First Core and Main Accretion Phase

4. Multiple Star Formation

1. Dynamical Fragmentation of Massive Clouds

IV - Pre-Main Sequence Stars

1 - T-Tauri Stars

1. Line and Continuum Emission
2. Outflow and Infall
3. Circunstellar Disks
4. Post-T Tauri Stas and Beyond

2 - Herbig Ae/Be Stars

1. Basic Propreties
2. Gaseous and Debris Disks

V - Accretion discs
1. Theory of standard accretion discs

1. Equations of conservation and the difusion equation
2. Stationary discs
3. Boundary conditions

2. Observations vs Theory

1. Spectral Energy distribution
2. Spectral emission from an optically thick steady disc
3. Sources of excess emission

3. Introduction to accretion shock models

Mandatory literature

Stahler Steven W.; The formation of stars. ISBN: 3-527-40559-3
Frank J.; Accretion power in astrophysics

Complementary Bibliography

Gray David F.; The observation and analysis of stellar photospheres. ISBN: 0-521-85186-6
Lee Hartmann; Accretion Processes in Star Formation, Cambridge University Press, 2009. ISBN: 978-0-521-53199-3

Teaching methods and learning activities

Multimedia presentations and Tutorial guidance.

The support material of the course will be available via the Moodle UP, including a copy of the slides used. There is a main reference book that is the main bibliography, but for some components of the course complementary bibliography and/or scientific articles may be used.

Software

Latex
Python

keywords

Physical sciences
Physical sciences > Astronomy
Physical sciences > Astronomy > Astrophysics

Evaluation Type

Distributed evaluation with final exam

Assessment Components

designation	Weight (%)
Exame	70,00
Trabalho prático ou de projeto	30,00
Total:	100,00

Amount of time allocated to each course unit

designation	Time (hours)
Apresentação/discussão de um trabalho científico	10,00
Estudo autónomo	70,00
Frequência das aulas	42,00
Trabalho escrito	40,00
Total:	162,00

Eligibility for exams

The student has frequency to the course if he/she misses no more than 1/3 of the planned classes.

Calculation formula of final grade

The final grade is obtained through two components:
1) 70% - a final written exam
2) 30% - small project developped during the semester with a final written report

Examinations or Special Assignments

Pratical work task with written report.  This task will be done throughout the semester. Paper presentation and discussion.

Classification improvement

The student may improve the classification in the written exam (weight of 70% in the final classification). It will not be possible to improve the classification in the pratical work task.

Observations

Jury:
Pedro Palmeirim
João Lima
Catarina Lobo