Astronomy C

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Astronomer252
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Re: Astronomy C

Postby Astronomer252 » April 14th, 2015, 9:38 pm

Can someone explain 2M1207? I don't understand if the companion "planet" 2M1027b is actually a planet, or if it's another brown dwarf or something. I read that evidence suggests that 2M1207b wasn't formed from a circumstellar disk, and because 2M1207 isn't a star, 2M1027b isn't a planet. However, I thought it was significant because it was the first direct image of an extrasolar planet. Also, does 2M1207 orbit around a star?
I think I just need to understand brown dwarves a little bit better. I get the basic concept, but when I start looking at pictures and trying to identify which object is the brown dwarf (for example, pictures of Gliese 229b), I just get confused. Do brown dwarves orbit around stars?
Thanks!!
2013-14 Placements- WSU/ Lisle/ Grayslake/ Regionals/ State/ Nationals
Solar System: 1/1/2/1/1/18
Helicopters:15/1/3/3/4/18
Dynamic Planet:4/1/1/1/3/23
Team:3/2/2/1/2/14

2014-15 Placements- Regionals/ State
Astronomy: 3/?
Dynamic Planet: 1/?
Geologic Mapping: 2/?
Team: 4/?

syo_astro
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Re: Astronomy C

Postby syo_astro » April 15th, 2015, 10:56 am

Can someone explain 2M1207? I don't understand if the companion "planet" 2M1027b is actually a planet, or if it's another brown dwarf or something. I read that evidence suggests that 2M1207b wasn't formed from a circumstellar disk, and because 2M1207 isn't a star, 2M1027b isn't a planet. However, I thought it was significant because it was the first direct image of an extrasolar planet. Also, does 2M1207 orbit around a star?
I think I just need to understand brown dwarves a little bit better. I get the basic concept, but when I start looking at pictures and trying to identify which object is the brown dwarf (for example, pictures of Gliese 229b), I just get confused. Do brown dwarves orbit around stars?
Thanks!!
What do you mean "explain it"? You can start with wikipedia http://en.wikipedia.org/wiki/2M1207b, but then just start looking at papers from adsabs/arxiv/even press releases if you really want to know what the new data is saying. Though, why do you think the brown dwarf orbits a star? Are you confused by what the directly imaged system shows? Be careful with the "first x and x" stuff, sometimes astronomers revisit major discoveries and find oh it was really due to some other factor (eg. variability, background objects). In this case, of course, I agree confusion is for a different reason. I assume you're confused by the paragraph saying it is generally mentioned as the first direct image of an exoplanet, but the IAU definition of a planet confuses things? But then that's simply something to look up: how do we define a planet/how do planets form, and what research goes on with 2M1207b?

There's a lot you're mentioning, and it's definitely all good to look into for the competition, but I'm a bit confused what exactly you're looking for help with (eg. is it just pointing to random sites off google about brown dwarfs, planet formation, papers on 2M1207b, etc?).

Off the top of my head I believe a brown dwarf could orbit a star, but I can't think of any specific systems on the other hand. I don't see why not, though? But it's not like something has to have a brown dwarf-star system, just the same as not everything has to have a planet. Are you confused that a brown dwarf is a "failed star" because it didn't have enough mass to go past the pre-main sequence phase onto the main sequence? If it's just ID, then that's practice. If you collect tons of images and organize them, you'll be plenty prepared to know what in the picture is a star/brown dwarf/exoplanet. One major piece of advice is to understand what wavelength the image is in. If you know it's an IR or a radio image that gives some major hints about what could be emitting such radiation.
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Re: Astronomy C

Postby sciolymom » April 16th, 2015, 3:46 pm

Phase vs Period

On some of the charts it gives "phase" rather than "period" at the bottom. Is there any way to understand what the period is if they only give you phase? I had phase explained to me (as in a repetition of data) but I don't totally get it or if it still relates directly to period.
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Re: Astronomy C

Postby finagle29 » April 16th, 2015, 4:22 pm

Phase is fraction of a period, so light curves that go from phase 0 to phase 1 display a full period. Light curves that give you phase and no indication of period are trying to make you calculate period some way other than looking at the graph.
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Re: Astronomy C

Postby Astronomer252 » April 16th, 2015, 5:47 pm

Can someone explain 2M1207? I don't understand if the companion "planet" 2M1027b is actually a planet, or if it's another brown dwarf or something. I read that evidence suggests that 2M1207b wasn't formed from a circumstellar disk, and because 2M1207 isn't a star, 2M1027b isn't a planet. However, I thought it was significant because it was the first direct image of an extrasolar planet. Also, does 2M1207 orbit around a star?
I think I just need to understand brown dwarves a little bit better. I get the basic concept, but when I start looking at pictures and trying to identify which object is the brown dwarf (for example, pictures of Gliese 229b), I just get confused. Do brown dwarves orbit around stars?
Thanks!!
What do you mean "explain it"? You can start with wikipedia http://en.wikipedia.org/wiki/2M1207b, but then just start looking at papers from adsabs/arxiv/even press releases if you really want to know what the new data is saying. Though, why do you think the brown dwarf orbits a star? Are you confused by what the directly imaged system shows? Be careful with the "first x and x" stuff, sometimes astronomers revisit major discoveries and find oh it was really due to some other factor (eg. variability, background objects). In this case, of course, I agree confusion is for a different reason. I assume you're confused by the paragraph saying it is generally mentioned as the first direct image of an exoplanet, but the IAU definition of a planet confuses things? But then that's simply something to look up: how do we define a planet/how do planets form, and what research goes on with 2M1207b?

There's a lot you're mentioning, and it's definitely all good to look into for the competition, but I'm a bit confused what exactly you're looking for help with (eg. is it just pointing to random sites off google about brown dwarfs, planet formation, papers on 2M1207b, etc?).

Off the top of my head I believe a brown dwarf could orbit a star, but I can't think of any specific systems on the other hand. I don't see why not, though? But it's not like something has to have a brown dwarf-star system, just the same as not everything has to have a planet. Are you confused that a brown dwarf is a "failed star" because it didn't have enough mass to go past the pre-main sequence phase onto the main sequence? If it's just ID, then that's practice. If you collect tons of images and organize them, you'll be plenty prepared to know what in the picture is a star/brown dwarf/exoplanet. One major piece of advice is to understand what wavelength the image is in. If you know it's an IR or a radio image that gives some major hints about what could be emitting such radiation.
Thank you so much! I think that the major thing I was confused about was whether or not 2M1207b can be called a planet. I looked into it some more, and I think that everything is cleared up now. Since most sources say it is a planet, especially the first exoplanet directly imaged, I should just call it a planet, unless something on the test would suggest otherwise. Concerning the brown dwarves orbiting stars thing, I was just wondering about that because I'm not exactly sure how to classify a brown dwarf, since it is a "failed star". And if it isn't a star, then why couldn't it orbit around one (just as you said), and I wanted to see if anyone knew the answer. And thanks for the advice on ID! Everything makes much more sense now.
Last edited by Astronomer252 on April 16th, 2015, 5:49 pm, edited 1 time in total.
2013-14 Placements- WSU/ Lisle/ Grayslake/ Regionals/ State/ Nationals
Solar System: 1/1/2/1/1/18
Helicopters:15/1/3/3/4/18
Dynamic Planet:4/1/1/1/3/23
Team:3/2/2/1/2/14

2014-15 Placements- Regionals/ State
Astronomy: 3/?
Dynamic Planet: 1/?
Geologic Mapping: 2/?
Team: 4/?

syo_astro
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Re: Astronomy C

Postby syo_astro » April 16th, 2015, 5:49 pm

Just to add as an example. You could say get the period by Kepler's third law (based on some appropriate data given), and with that they could then ask you how long based on the graph does an eclipse take (you would have to use the graph to estimate the phase, which then simply multiplies into the period, since phase = portion/period...0.2 phase would mean it's 2/10 of the period).

Edit: to the last post to make it more definitive, Donna Young on her astro presentation on aavso->chandra I believe said brown dwarfs are pre-main sequence stars, so think of them like that. This isn't a terrible thing to say either if you understand their evolution and what processes they use to sustain hydrostatic equilibrium, etc. I'll at least tell you that you should certainly know how the Jeans Mass works in and that that basically separates stars from brown dwarfs when you have collapsing masses of dust and stuff. If you find some specific concepts annoying/can't find how they evolve at all give a shout out again!

For the planet thing it's definitely good to look into, but it's good you've at least recognized that there's some debate about it (sounds like you've looked it up anyway...).

Lastly for the bit about the star, I'm sure you know one of the DSOs this year has a brown dwarf orbiting a red dwarf (thus a star) :).
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C: Microbe Mission, DyPlan (Earth's Fresh Waters), Fermi Questions, GeoMaps, Gravity Vehicle, Scrambler, Rocks, Astronomy
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Re: Astronomy C

Postby sciolymom » April 24th, 2015, 1:42 pm

Just want to say thank you to everyone on here that helped so much this year! My daughter and her partner won 1st place at regionals and at state in Astronomy, which she wasn't expecting at all. We struggled with this event all year (her first year on the event). You guys were so helpful answering my questions so we could get a better understanding of things. She wants to do Astronomy again next year... Not sure how I feel about it though! ;)
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Re: Astronomy C

Postby syo_astro » April 24th, 2015, 5:43 pm

Just want to say thank you to everyone on here that helped so much this year! My daughter and her partner won 1st place at regionals and at state in Astronomy, which she wasn't expecting at all. We struggled with this event all year (her first year on the event). You guys were so helpful answering my questions so we could get a better understanding of things. She wants to do Astronomy again next year... Not sure how I feel about it though! ;)
I can tell you I'm always happy to help ;). Good job to her and your team!
B: Crave the Wave, Environmental Chemistry, Robo-Cross, Meteorology, Physical Science Lab, Solar System, DyPlan (E and V), Shock Value
C: Microbe Mission, DyPlan (Earth's Fresh Waters), Fermi Questions, GeoMaps, Gravity Vehicle, Scrambler, Rocks, Astronomy
Grad: Writing Tests/Supervising (NY/MI)

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Re: Astronomy C

Postby JCicc » April 26th, 2015, 5:43 pm

Watch the test exchange for PA SE Regional and PA State tournament astronomy exams. I should have them up soon.

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Re: Astronomy C

Postby Techsam » April 26th, 2015, 6:57 pm

Watch the test exchange for PA SE Regional and PA State tournament astronomy exams. I should have them up soon.

That would be awesome! They were both good and challenging tests :)


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