Star formation

Samenvattingen

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Algemeen

This course is taught by professor Alexander De Koter alongside a teaching assistant who takes charge of the exercise sessions. The professor has a relaxed style of teaching with a great emphasis on physical understanding during his lectures instead of e.g. mathematical derivations. That is not to say that you will not learn those, they can be found in the course notes and you'll regularly encounter them during the exercise sessions. It is strongly recommended to attend all the lectures as they provide a great basis for understanding more difficult physical concepts. Furthermore, as the professor encourages a lot of interaction during his lectures, you get many opportunities to ask all kinds of questions. Finally, 'Alex' is simply a good teacher, plain and simple. The lecture notes are well written and complete and can carry the course on their own if they need to. It is highly recommended you print these rather than working with an online pdf.

The exam is closed book and entirely written (with absolutely no exeptions) and consists usually of 6 questions that you have to solve in 3 hours. More often than not, the questions are not that difficult and because there are many sub-questions, you'll be able to pick up parts of the grades for each question. Time, however, is enemy number one as it is not uncommon to not have finished writing at the end of your 3 hours. As such, practice the basics so that you'll never have to think about those for too long and above all: be brief! Two questions are exercises, similar to those in the exercise sessions, one consists of 10 'true or false' questions, two are essay questions and one asks you to briefly explain 6 concepts.

Exams

Exam 17 August 2021

Media:SPF exam.pdf

Exam 1 June 2015

1) Explain next concepts:

* Virial theorem
* Accretion luminosity
* Fragmentation-induced starvation
* First stars
* Dead zone

2) Exercise: Given a rotation spherical cloud. It collapses to a binary system and a circumstellar disk. Given: R_cloud, Omega_cloud, M_cloud, M_stars, R_stars, Separation stars, M_disk, Keplerian orbitial period

* Calculate moment of inertia of flat disk
* Calculate angular momentum of that disk
* Calculate R_end of disk in AU
* Discuss three possibles way of removing angular momentum

3) Explain classifications by Lada. Given SED's of all classes.

* How classified
* Which SED is which class
* Discuss optical depth
* Discuss Birthline
* Discuss Timescales
* Weak-lined and classica T Tauri + debris disk

4) Exercise: Razor-thin disk, v_r = $-\frac{3}{\mathrm{\Sigma }\sqrt{r}}\frac{\partial }{\partial r}(\nu \mathrm{\Sigma }\sqrt{r})\mathrm{\$}$ and $\nu =\frac{\dot{M}}{3\nu \mathrm{\Sigma }}$ and $\mathrm{\Sigma }(r)={\mathrm{\Sigma }}_0(\frac{r}{r_0}{)}^{-\alpha }$.

• Give v_r for alpha=3/2.
• How long does it take to fall into the star from 10 AU.
• Does this depent on surface density? If yes, for what alpha is v_r constant?

5) Formation of massive stars has some issues. Discuss 4 out of 5 and how to solve them. 6) True or False questions.

Examen gent 9 juni 2011

1) Leg uit inside-out collapse, waarom is dit fysisch aannemelijk + wat wiskundig uitwerken

2) De CMF en IMF hun voorspelde massa verschilt ongeveer een factor 6, leg uit waarom.

3) Hot Jupiters, leg uit hoe ze kunnen ontstaan.

Examen Leuven 16 juni 2011

1) Wat is de invloed van de massa/metalliciteit van een wolk op de stervorming. Hoe meet men dat observationeel.

2) De CMF en IMF verschillen van een factor 5 à 8, maar de curves zien er gelijkaardig uit. Leg uit, de gelijkenissen en verschillen, en hoe ze te verklaren zijn.

3) Selfshadowed disks vs flared disks. Hoe observeert men disks, en hoe kan men observationeel het verschil zien tussen de twee types.

4) Hot jupiters zijn hot. Voor de ontdekking van exoplaneten verwachtte men dit niet, waarom? Leg ook de (drie) methodes uit hoe dit kan gebeuren.