Astronomy C

[brayden box]

Event for 2016 science Olympiad!

[Unome]

I would suggest you read this post (which for some reason isn't in this year's forums)

[brayden box]

Sorry about that.

What Is a Black Hole?

[AlphaTauri]

Black holes are not part of the event for this year, since the topics are star & planet formation and exoplanets.

But I'll answer it anyway... (Click to Show Hidden Text)

A black hole is a massive compact object that warps spacetime so much that its escape velocity is greater than the speed of light, thus appearing "black" to us because no EM radiation from it can reach us. It can be completely described by three characteristics: mass, charge, and spin (though charge and spin may be zero). Stellar mass black holes are thought to be the result of massive stars going Type II SN and their remnant cores being too massive to be supported by neutron degeneracy pressure. Supermassive black holes are exactly what they sound like and located at the center of (we think) every galaxy and that's about the extent of my knowledge offhand because it's been far too long since I've done galaxies.

Here's a softball question for y'all: Why did the discovery of 51 Pegasi b cause issues with the accepted models of planetary formation theory?

[brayden box]

Everyone thought that the only planets that existed were inside our solar system.

What is a supernova

[AlphaTauri]

Incorrect. Anyone else want to try?

Please try to keep questions relevant to this year's topics and rules. Also, note that Astronomy is a Div C event and the level of the questions in the QM should reflect that.

[Adi1008]

Black holes are not part of the event for this year, since the topics are star & planet formation and exoplanets.

But I'll answer it anyway... (Click to Show Hidden Text)

A black hole is a massive compact object that warps spacetime so much that its escape velocity is greater than the speed of light, thus appearing "black" to us because no EM radiation from it can reach us. It can be completely described by three characteristics: mass, charge, and spin (though charge and spin may be zero). Stellar mass black holes are thought to be the result of massive stars going Type II SN and their remnant cores being too massive to be supported by neutron degeneracy pressure. Supermassive black holes are exactly what they sound like and located at the center of (we think) every galaxy and that's about the extent of my knowledge offhand because it's been far too long since I've done galaxies.

Here's a softball question for y'all: Why did the discovery of 51 Pegasi b cause issues with the accepted models of planetary formation theory?

Answer (Click to Show Hidden Text)

Before the discovery of 51 Pegasi b, most astronomers thought that you couldn't have very large planets in very short (phrasing?) orbits around their stars. However, Bellerophon was big and very close to its star (which is what made it relatively easy to detect) which went against the previously accepted ideas of planetary formation. This led to a new class of planets known as Hot Jupiters, which are Jupiter-like planets (big gas giants) very close to the star they orbit, and as a result, hot

Everyone thought that the only planets that existed were inside our solar system.

What is a supernova

Bellerophon wasn't the first exoplanet to be discovered - that happened in 1992 while 51 Pegasi b was discovered in 1995. Even then, I'm sure that people thought planets existed outside of the solar system

[AlphaTauri]

Correct. Your turn.

Btw, if you're curious about how exoplanetology as a whole has influenced the core-accretion theory, check out this article: http://www.nature.com/news/astronomy-pl ... os-1.15480

[Adi1008]

Correct. Your turn.

Btw, if you're curious about how exoplanetology as a whole has influenced the core-accretion theory, check out this article: http://www.nature.com/news/astronomy-pl ... os-1.15480

Thanks for the article AlphaTauri. Looks like an interesting read.

What are pre-main sequence stars with less mass than a Herbig Ae/Be star called? What are they powered by instead of hydrogen fusion (because they are too small)?

[Magikarpmaster629]

Correct. Your turn.

Btw, if you're curious about how exoplanetology as a whole has influenced the core-accretion theory, check out this article: http://www.nature.com/news/astronomy-pl ... os-1.15480

Thanks for the article AlphaTauri. Looks like an interesting read.

What are pre-main sequence stars with less mass than a Herbig Ae/Be star called? What are they powered by instead of hydrogen fusion (because they are too small)?

They are (Click to Show Hidden Text)

T Tauri stars, powered by the gravity of falling gas. As a small core forms from a molecular cloud, the gas 'falls' into the T Tauri, generating heat energy from gravitational potential energy.