Astronomy C

AlphaTauri
Staff Emeritus
Staff Emeritus
Posts: 829
Joined: September 11th, 2009, 1:41 pm
Division: Grad
State: PA
Location: 04h 35m 55.239s, +16° 30′ 33.49″
Contact:

Re: Astronomy C

Postby AlphaTauri » March 10th, 2014, 8:52 pm

There was a question that came up today that I remember also came up a while ago, but I wasn't quite able to dig it up from my notes.

"This object contains many Type II Supernovae remnants along with many Class O stars" (or something to that effect).
Was it in relation to a DSO, or was it just some general type of object? Maybe it could relate to an OB assocation?
It was a DSO.
My best guess would be Trapezium, like Mr. Cicc said -- a bright cluster of O/B stars and many young protostars. Definitely conceivable that some are forming from the remnants of the more massive stars in the cluster.

There is also a remote possibility that it could be attempting to refer to Eta Carinae, though it's a bit of a stretch as the question would have to be referring to the entire Carina Nebula instead of Eta Car itself.
Hershey Science Olympiad 2009 - 2014
Volunteer for Michigan SO 2015 - 2018

]\/[ Go Blue!

User avatar
Tiktaalik
Member
Member
Posts: 13
Joined: February 13th, 2013, 5:24 pm
Division: C
State: PA
Location: a Devonian marsh on Ellesmere Island
Contact:

Re: Astronomy C

Postby Tiktaalik » March 10th, 2014, 8:55 pm

Does anyone know where a good complete list of all the objects in the Henry Draper catalogue can be found? I've been able to find most of the other important star catalogues we might need to use.

Smithy0013
Member
Member
Posts: 38
Joined: November 21st, 2012, 6:43 pm
Division: C
State: PA

Re: Astronomy C

Postby Smithy0013 » March 11th, 2014, 12:12 pm

So why use B-V index to find temperature of a star when you can use Wien's law? What is the point of B-V index besides finding Temp?

Schrodingerscat
Administrator
Administrator
Posts: 343
Joined: March 2nd, 2011, 7:10 pm
Division: Grad
State: KS
Location: Kansas City metro

Re: Astronomy C

Postby Schrodingerscat » March 11th, 2014, 1:30 pm

So why use B-V index to find temperature of a star when you can use Wien's law? What is the point of B-V index besides finding Temp?
For one, from an observational standpoint, one can measure B-V index with just two magnitude measurements with a B and a V filter, as opposed to needing a full spectrometer to use Wien's law. Otherwise, it is just another way to measure temperature/color of a star to my knowledge.

astro124
Member
Member
Posts: 44
Joined: November 23rd, 2012, 1:44 pm
Division: C
State: AZ
Location: Phoenix, AZ

Re: Astronomy C

Postby astro124 » March 11th, 2014, 5:07 pm

So why use B-V index to find temperature of a star when you can use Wien's law? What is the point of B-V index besides finding Temp?
For one, from an observational standpoint, one can measure B-V index with just two magnitude measurements with a B and a V filter, as opposed to needing a full spectrometer to use Wien's law. Otherwise, it is just another way to measure temperature/color of a star to my knowledge.
Isn't Wien's law more common to use (at least on Scioly tests)? On my state test a few weeks ago I remember seeing two maximum wavelength to temperature problems but zero B-V color index questions. That being said, you'll regularly see B-V color on the X-axis of H-R diagrams.

Also, can anybody help me with a quick binary system question. When I went to take the Arizona astro test there were two questions were they gave us the velocity of a binary system, the average rotational period of the two objects, and the mass of one of the objects. From there they asked us to calculate the mass of the second object. Thanks!
2012 Season: Reach for the Stars-3rd (State) / Keep the Heat-19th (State)
2013 Season: Astronomy-2nd (State) / Disease Detectives-15th (State)
2014 Season: Astronomy-1st (State) / Experimental Design-20th (State)/ Anatomy and Physiology-16th (State)
2015 Season: Astronomy

Thunder

User avatar
pjgscioisamazing
Member
Member
Posts: 539
Joined: February 14th, 2008, 3:46 pm
Division: Grad
State: NY

Re: Astronomy C

Postby pjgscioisamazing » March 11th, 2014, 5:25 pm

So why use B-V index to find temperature of a star when you can use Wien's law? What is the point of B-V index besides finding Temp?
For one, from an observational standpoint, one can measure B-V index with just two magnitude measurements with a B and a V filter, as opposed to needing a full spectrometer to use Wien's law. Otherwise, it is just another way to measure temperature/color of a star to my knowledge.
Isn't Wien's law more common to use (at least on Scioly tests)? On my state test a few weeks ago I remember seeing two maximum wavelength to temperature problems but zero B-V color index questions. That being said, you'll regularly see B-V color on the X-axis of H-R diagrams.
Wien's Law is more common on Scio tests as it is a simple relation that is easy to understand and use. B-V and temperature relations are much more complicated, depending on terms of B-V to different powers with differing coefficients that are affected by things such as metallicity and the life stage of a star.

Wien's Law is for blackbodies, and stars are only approximated as black bodies. Wien's Law gives the temperature of a blackbody that would emit the same total amount of light as the star, called the effective temperature.

Also, as said above, in observational astronomy you will be working with magnitudes of stars in some sort of filter system, commonly UBVRI. A common goal, especially in studies of star clusters, is to generate an H-R Diagram to determine things like the age and distance of the cluster. It is easiest to use the B-V value as a temperature indicator. This is why most H-R Diagrams of star clusters will be Color-Magnitude Diagrams (ie. V magnitude versus B-V Index).
2007-2012. Paul J Gelinas Jr High and Ward Melville High School

Astronomy, Rocks & Minerals, MagLev, Dynamic Planet (E&V), Anatomy (Circulatory), Reach for the Stars, Meteorology (Climate), Remote Sensing, Disease Detectives, Metric Mastery, Pentathlon, Balloon Race, Tower Building

Smithy0013
Member
Member
Posts: 38
Joined: November 21st, 2012, 6:43 pm
Division: C
State: PA

Re: Astronomy C

Postby Smithy0013 » March 12th, 2014, 1:44 pm

So where is the best reliable source for info on DSOs? Like for distance im getting a lot of variance (for example, wikipedia says Mira is 300 ly away and this wiki says 420). Id rather not get points off from a strict test proctor because i have a 20 percent error

astro124
Member
Member
Posts: 44
Joined: November 23rd, 2012, 1:44 pm
Division: C
State: AZ
Location: Phoenix, AZ

Re: Astronomy C

Postby astro124 » March 12th, 2014, 1:53 pm

So where is the best reliable source for info on DSOs? Like for distance im getting a lot of variance (for example, wikipedia says Mira is 300 ly away and this wiki says 420). Id rather not get points off from a strict test proctor because i have a 20 percent error
If you can you should use the Chandra X-ray Observatory Website. This is the most reliable for DSO info, but unfortunately not all DSOs are listed there. However, for a good majority of the list I would spend some time looking around at different websites (wiki, NASA, Chandra, university websites, etc., academic papers, etc.). As with anything in astro you might get similar but not exact info from these different sources. The test proctor should understand.

Mira (Chandra): http://chandra.harvard.edu/photo/2005/mira
2012 Season: Reach for the Stars-3rd (State) / Keep the Heat-19th (State)
2013 Season: Astronomy-2nd (State) / Disease Detectives-15th (State)
2014 Season: Astronomy-1st (State) / Experimental Design-20th (State)/ Anatomy and Physiology-16th (State)
2015 Season: Astronomy

Thunder

darkwinters
Member
Member
Posts: 40
Joined: December 3rd, 2013, 6:14 pm
Division: C
State: IL

Re: Astronomy C

Postby darkwinters » March 13th, 2014, 5:01 pm

I remember something came up on last year's state test about observing elliptical motion when the orbital plane was tilted with respect to us.

I don't remember much of that question at this point, but has anyone come across something similar?

BipolarEconomist
Member
Member
Posts: 6
Joined: January 18th, 2014, 7:20 pm
Division: C
State: CT

Re: Astronomy C

Postby BipolarEconomist » March 20th, 2014, 9:56 pm

Do you guys recommend memorizing DSOs?
I know that a lot of our competition this year is going to be centered around the DSOs, but I'm bringing a laptop and binder with the SciOly wiki's charts with the information on DSOs with me, so I think I should be OK.

Also, I noticed that a lot of questions this year ask you about declination, flux, density, distance, etc. of DSOs. Some info. is on Wikipedia pages, some is not. Where do you guys find all the information? If you have any links, share pls? =D

Thanks!
2016: Fossils, Chem Lab, Astronomy


Return to “2014 Study Events”

Who is online

Users browsing this forum: No registered users and 1 guest