Astronomy C

[Adi1008]

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[math]LaTeX code here[/math]

Which DSO was the IAU petitioned to be renamed Gallifrey?

Answer (Click to Show Hidden Text)

HD 106906 b.

Thanks for the tip about LaTeX.

[finagle29]

Correct! Your turn.

It's no problem, I like to see pretty math as much as the next person.

[Adi1008]

Correct! Your turn.

It's no problem, I like to see pretty math as much as the next person.

What is unique about the inclination of 55 Cancri e's orbit? What effect was used to determine the inclination?

[Magikarpmaster629]

Correct! Your turn.

It's no problem, I like to see pretty math as much as the next person.

What is unique about the inclination of 55 Cancri e's orbit? What effect was used to determine the inclination?

Well (Click to Show Hidden Text)

Its inclination is 83 degrees, which nearly perpendicular to the plane of the debris disk. It was found using the observation of 55 cancri e's transit.

[Adi1008]

Correct! Your turn.

It's no problem, I like to see pretty math as much as the next person.

What is unique about the inclination of 55 Cancri e's orbit? What effect was used to determine the inclination?

Well (Click to Show Hidden Text)

Its inclination is 83 degrees, which nearly perpendicular to the plane of the debris disk. It was found using the observation of 55 cancri e's transit.

The inclination is like that because of the gravitational pull of the red dwarf in the system about 1000 AU away, 55 Cancri B (just something I thought was cool). I was looking for something more specific for the effect - it's an actual name and stuff, not something that general.

[doge]

Hmm.. (Click to Show Hidden Text)

I'm fairly sure I read that researchers concluded that 55 Cancri B did not have much of an influence on the inclination of e?
1. The orbital inclinations of the planets e and d vary significantly, possibly caused by e migrating inwards through two secular resonances
2. Rossiter McLaughlin Effect

[Adi1008]

Hmm.. (Click to Show Hidden Text)

I'm fairly sure I read that researchers concluded that 55 Cancri B did not have much of an influence on the inclination of e?
1. The orbital inclinations of the planets e and d vary significantly, possibly caused by e migrating inwards through two secular resonances
2. Rossiter McLaughlin Effect

I found the information regarding 55 Cnc B and its effects on the sky projected obliquity of 55 Cnc e here: Bourrier & Hebrard (2014), “Detecting the spin-orbit misalignment of the super-Earth 55 Cnc e”, arXiv:1406.6813 [astro-ph.EP]. I'm not sure now; where did you find stuff against that?

With a semi-major axis lower than about 4000 au the gravitationnal influence of 55 Cnc B is strong enough to significantly alter the alignment of the system, providing the star is on a highly eccentric orbit (e >∼0.95) (Bou´e & Fabrycky 2014). Kaib et al. (2011) predicted a true obliquity of ∼65◦, which is remarkably consistent with the sky-projected obliquity of 72.4+12.7−11.5◦ we derived and indicate that the rotation axis of 55 Cnc A is probably not much inclined toward the line of sight.

Etiher way, Rossiter McLaughlin effect was what I was looking for. Your turn!

[doge]

The presence of an M-dwarf companion at > 1000 AU can, in principle, induce precession of the planetary system (In-nanen et al. 1997; Kaib et al. 2011; Boue’ & Fabrycky 2014) if the orbit is sufficiently eccentric and inclined. However, the precession timescales are long compared to the time it takes 55 Canc e to cross the resonance, and so the orbit tilting discussed here is insensitive to the influence of the external companion. We have verified this by repeating five of the simulations which crossed the resonance but including a 0.26M⊙ companion with semi-major axis 1250 AU, eccentricity= 0.93 and inclination 115◦ as discussed by Kaibet al. (2011). In all cases the eccentricity and inclination excitation was reproduced, with rapid eccentricity pumping followed by circulation, and the final orbital tilt of 55 Canc e relative to the other planets.

This is from "On the potentially dramatic history of the Super-Earth rho 55 Cancri e" by Hansen & Zink (2015), so it seems like its more recent. But IDK, I might be misinterpreting this entire thing.

Nevertheless, here's the next question:
GD 165 is a binary system between a brown dwarf and what type of variable star? What general characteristic of this variable star does it exhibit (a property specific to that type of variable star, not like temperatures or whatnot) and what is significant about GD 165's display of this characteristic?

[Adi1008]

The presence of an M-dwarf companion at > 1000 AU can, in principle, induce precession of the planetary system (In-nanen et al. 1997; Kaib et al. 2011; Boue’ & Fabrycky 2014) if the orbit is sufficiently eccentric and inclined. However, the precession timescales are long compared to the time it takes 55 Canc e to cross the resonance, and so the orbit tilting discussed here is insensitive to the influence of the external companion. We have verified this by repeating five of the simulations which crossed the resonance but including a 0.26M⊙ companion with semi-major axis 1250 AU, eccentricity= 0.93 and inclination 115◦ as discussed by Kaibet al. (2011). In all cases the eccentricity and inclination excitation was reproduced, with rapid eccentricity pumping followed by circulation, and the final orbital tilt of 55 Canc e relative to the other planets.

This is from "On the potentially dramatic history of the Super-Earth rho 55 Cancri e" by Hansen & Zink (2015), so it seems like its more recent. But IDK, I might be misinterpreting this entire thing.

Nevertheless, here's the next question:
GD 165 is a binary system between a brown dwarf and what type of variable star? What general characteristic of this variable star does it exhibit (a property specific to that type of variable star, not like temperatures or whatnot) and what is significant about GD 165's display of this characteristic?

Looks like a good reading. Thank you.

As for the question...

I think (Click to Show Hidden Text)

1. binary system between a brown dwarf and a pulsating white dwarf (ZZ Ceti/DAV stars)
2. not sure what exactly, but could it be very short period for variation in brightness (on order of minutes). The pulsating nature is because of ionization and recombination of hydrogen in the outer envelope of the star.
3. GD 165 A has a super long period for the main change in brightness (up to 0.1 mag), about 1800 seconds, the longest ever recorded for a ZZ Ceti.

[doge]

Correct!