Astronomy C

[Adi1008]

Ehh, here goes
A. Different evolutionary tracks?
B. A, D, C, B
C. ~50,118 K

Exactly!

Your turn

[Magikarpmaster629]

Ehh, here goes
A. Different evolutionary tracks?
B. A, D, C, B
C. ~50,118 K

Exactly!

Your turn

B. and C. were easy, but A definitely needs an explanation. I'm guessing each of the different evolutionary tracks had some variable different- was this variable radius? And why would its gravitational field strength go up as temperature goes down?
EDIT: And could you link the paper where you found it too?

I'm in class now, I'll write a question later.

[Adi1008]

Ehh, here goes
A. Different evolutionary tracks?
B. A, D, C, B
C. ~50,118 K

Exactly!

Your turn

B. and C. were easy, but A definitely needs an explanation. I'm guessing each of the different evolutionary tracks had some variable different- was this variable radius?

I wrote some stuff in response to Unome in the general Astronomy thread; it'll provide additional information too.

The different things about the evolutionary tracks is the mass of the post AGB star. As time went on, the stars changed, so their radii, luminosity, etc changed too. The independent variable here is mass, not radius.

And why would its gravitational field strength go up as temperature goes down?

I might be misunderstanding you, but the y axis is inverted. Larger numbers for log(g) are at the bottom, and are when the temperature is higher. The surface gravity increases as the temperature increases, not the other way around

This makes sense if you think about gas laws. Consider compressing a gas - it would heat up; this is just Gay-Lussac's Law. Surface gravity is inversely proportional to the inverse of the square of the radius, so a smaller star (e.g. a more compressed star) will have a stronger surface gravity, as the mass is the same, it's just in a smaller space. You can tell the surface gravity is growing because of the width of the spectral lines, and the increase in the surface gravity means that the radius is smaller. A smaller radius also means a lower luminosity. this makes sense - white dwarfs are hot, but because of their small size, they aren't very luminous. The same case applies here.

[Magikarpmaster629]

Sorry this took so long!

1. Which DSOs does this image depict (note the size difference of the two objects)?
2. These DSOs are progenitors of what type of binary star system?
3. These DSOs are potentially progenitors of what two types of explosions? Briefly describe each explosion type.

[bhavjain]

Sorry this took so long!

1. Which DSOs does this image depict (note the size difference of the two objects)?
2. These DSOs are progenitors of what type of binary star system?
3. These DSOs are potentially progenitors of what two types of explosions? Briefly describe each explosion type.

Answer (Click to Show Hidden Text)

1. J075141 and J174140.
2. AM CVn binary system.
3. Type Ia Supernovae - the heavier white dwarf accretes enough mass to surpass the Chandrasekhar limit of 1.4 solar masses, accumulating enough pressure and exploding.
.Ia supernovae - the explosion occurs only on the surface of the star, leaving it simply damaged. The explosion is 1/10 the brightness of a Type Ia supernovae.

[Magikarpmaster629]

Sorry this took so long!

1. Which DSOs does this image depict (note the size difference of the two objects)?
2. These DSOs are progenitors of what type of binary star system?
3. These DSOs are potentially progenitors of what two types of explosions? Briefly describe each explosion type.

Answer (Click to Show Hidden Text)

1. J075141 and J174140.
2. AM CVn binary system.
3. Type Ia Supernovae - the heavier white dwarf accretes enough mass to surpass the Chandrasekhar limit of 1.4 solar masses, accumulating enough pressure and exploding.
.Ia supernovae - the explosion occurs only on the surface of the star, leaving it simply damaged. The explosion is 1/10 the brightness of a Type Ia supernovae.

A .Ia supernova isn't necessarily 1/10th the brightness, only a 'fraction' of the brightness. Also, the explosions are thermonuclear driven, not simply pressure driven. Otherwise correct.

[bhavjain]

Describe the triple-alpha and alpha process. What happens when a massive star fuses iron?

[Unome]

Some stuff (hopefully correct) (Click to Show Hidden Text)

Pretty sure the triple-alpha process is 3 helium atoms forming a carbon atom. Iron fusion has a negative energy yield, so the star basically starts losing it's energy (or something like that, idk).

[sciduck]

Some stuff (hopefully correct) (Click to Show Hidden Text)

Pretty sure the triple-alpha process is 3 helium atoms forming a carbon atom. Iron fusion has a negative energy yield, so the star basically starts losing it's energy (or something like that, idk).

Adding on:

(Not even sure if this is right) (Click to Show Hidden Text)

i think the helium atoms are specifically alpha particles (2 neutrons) and iron fusion absorbs energy --> temperature drop(?)

[bhavjain]

Some stuff (hopefully correct) (Click to Show Hidden Text)

Pretty sure the triple-alpha process is 3 helium atoms forming a carbon atom. Iron fusion has a negative energy yield, so the star basically starts losing it's energy (or something like that, idk).

Adding on:

(Not even sure if this is right) (Click to Show Hidden Text)

i think the helium atoms are specifically alpha particles (2 neutrons) and iron fusion absorbs energy --> temperature drop(?)

Correct. Also, the alpha process converts helium into heavier elements, a process seen in heavy main sequence stars.