Reach for the Stars B

[AstroKing]

Ok, so let's try a mix of problems...

1. Stellar Evolution: What does the Roche Lobe dignify? What happens if a star overflows it's Roche Lobe. What is the Eddington Limit? Which star approaches the limit, and which DSO on the list is it in, and what galaxy is that DSO in?

2. DSO's: https://www.abc.net.au/reslib/200802/r227783_905819.jpg Identify this DSO. How far away is it? What type of DSO is it? What is the rate of speed production compared to the Milky Way? How often does this DSO give birth to a star? This DSO is the dimmest and farthest DSO. Correct this sentence. Which telescope was this discovered by?

3. Calculations: Find each of the following: parallax angle (degrees), recessional velocity, distance (AU), the difference between absolute magnitude and apparent magnitude, radiated energy, orbital period and surface area of the star. The star is moving away from us at 50 km/s, the star's peak wavelength is 94 nanometers, and the radiated flux from the star is 20, and the luminosity is 0.00025 the Sun's luminosity in Watts.


This is the first problem that I posted in "Question Marathons", so please review the questions, answer them, and let me know your comments!
Also, if you find Question 3 hard, ask for a hint!!

[Locoholic]

Ok, so let's try a mix of problems...



1. Stellar Evolution: What does the Roche Lobe dignify? What happens if a star overflows it's Roche Lobe. What is the Eddington Limit? Which star approaches the limit, and which DSO on the list is it in, and what galaxy is that DSO in?

2. DSO's: https://www.abc.net.au/reslib/200802/r227783_905819.jpg Identify this DSO. How far away is it? What type of DSO is it? What is the rate of speed production compared to the Milky Way? How often does this DSO give birth to a star? This DSO is the dimmest and farthest DSO. Correct this sentence. Which telescope was this discovered by?

3. Calculations: Find each of the following: parallax angle (degrees), recessional velocity, distance (AU), the difference between absolute magnitude and apparent magnitude, radiated energy, orbital period and surface area of the star. The star is moving away from us at 50 km/s, the star's peak wavelength is 94 nanometers, and the radiated flux from the star is 20, and the luminosity is 0.00025 the Sun's luminosity in Watts.

This is the first problem that I posted in "Question Marathons", so please review the questions, answer them, and let me know your comments!
Also, if you find Question 3 hard, ask for a hint!!

First of all, the tradition is to wait until the person who posted the questions checks your answers before you ask your own questions. No worries though! All of your answers were right, and for question 1, it's that Population III is the hypothetical one and Population I is the youngest one.

1. The Roche lobe in binary systems shows the object's field of gravitation; objects within a star's Roche lobe are gravitationally bound to it. I think mass transfer happens when this overflows. The Eddington limit is the maximum luminosity a star can achieve to maintain hydrostatic equilibrium.

2. I might be wrong but based on what it looks like and other context clues, I am fairly sure this is the baby boom galaxy. It's 12.2 billion ly away. It's a starburst galaxy. For the following parts of the question I've had differing sources but I'll try my best. It churns out stars at a rate 400 times that of the MWG. Its rate of star formation is ~4,000 per year, equating to 1 star in ~11 days. To correct the sentence, Gn-z11 is the farthest DSO, and we haven't found the "dimmest" DSO. For the last question, if you're still talking about the baby boom galaxy, it was co-discovered by a few telescopes at different wavelengths, notably Spitzer and the James Clerk Maxwell telescope.

3. Correct me if I'm wrong here, but I don't see anything in the question that gives a clue as to what the distance to the star is, unless by radiated flux you mean its brightness? Still, I don't know the units you're using here. Can you please clarify this? Thanks.



Great questions for your first post! Just need a little clarification on #3 before solving.

[AstroKing]

Nice Job on the first few problems!

1.

Click to Show Answer

Correct!!

2.

Click to Show Answer

Correct!, The answer to the last part was that R136a1 (most massive star), approaches the limit, in Tarantula Nebula (30 Doradus) and in LMC. 

3. For the last one, you have to use a combination of formulas including (Stefan Boltzmann, Wein's, Distance Modulus, Stellar Parallax, Hubble's Third Law and more!). I tried to cover all of the concepts in one problem!!

Your Turn!!


Also, how do you guys format your cheatsheets? Can I see a preview of your cheatsheet, to check if the formatting of my cheatsheet is alright, if that's allowed?

[Locoholic]

Nice Job on the first few problems!

1.

Click to Show Answer

Correct!!

2.

Click to Show Answer

Correct!, The answer to the last part was that R136a1 (most massive star), approaches the limit, in Tarantula Nebula (30 Doradus) and in LMC. 

3. For the last one, you have to use a combination of formulas including (Stefan Boltzmann, Wein's, Distance Modulus, Stellar Parallax, Hubble's Third Law and more!). I tried to cover all of the concepts in one problem!!

Your Turn!!


Also, how do you guys format your cheatsheets? Can I see a preview of your cheatsheet, to check if the formatting of my cheatsheet is alright, if that's allowed?

Oops, didn't answer all of question 1! Wouldn't have known that anyway, though.

For 3, I guess I'll just assume that by radiated flux you mean energy received by us per unit area, in W/m^2. In that case, I started with recessional velocity, which is simply the value given in the problem, 50 km/s. Next, I found temperature. If the star's peak wavelength is 94 nm, we can use Wien's Law to find that the star's temperature is ~30850 K when using a displacement constant of 2900 micrometers. This was simplified for ease of later calculations. Now, we have temperature and luminosity (9.57*10^22 Watts based on the Sun's luminosity), so we can find the star's surface area using the Stefan Boltzmann Law with the equation 9.57*10^22 = (x)*30850^4. This obtains x, the surface area, to be ~105655.3 meters. Now, to find the distance to the star, I have to use its radiated flux of 20. Here, I used the inverse square law, and compared this star with the Sun. I know that we receive around 1367 W/m^2 of the sun, and we hypothetically receive 20 W/m^2 from this star. Using the distance between the Earth and the sun of 1 AU, 1367 =1367*1/1^2 from the inverse square law, and using the same constant, we can write an equation for the star, 20 = 1367*1/x^2. Solving for x gives a value of ~8.3 AU. Now, we can find parallax. 8.3 AU equates to ~4.024*10^-5 pc. Using d = 1/p, this gives a parallax angle of ~24850.9 arcseconds. Next, I found the difference between the apparent and absolute magnitude of the star, which is the star's distance modulus. x = 5log₁₀(4.024*10^-5) - 5. This makes the distance modulus -27, or a difference of 27 between the absolute and apparent magnitude. Next, I found radiated energy, which I believe is just luminosity, making it 9.57*10^22 Watts. I believe the only thing left now is orbital period, which I couldn't solve because I think we need to know the mass of the star first... Overall, this was so much fun to solve! I hope I didn't mess up somewhere (I probably did though because I'm really tired rn).

About my cheat sheet, that's a question you should ask in a Private Message. I don't think my coaches would let me share a preview of my cheat sheet tho, so sorry :(. But I can tell you that I use size 3 Helvetica font with 0.25 margins, a page of words, and a page of images.

Before I post questions, though, I want you to check my math so I know if I did it right.

Cheers!

[AstroKing]

3. You're steps and the equations that you used were all correct, so nice job with that. This was really hard because you had to incorporate a wide variety of formulas and equations, that some of which weren't on the syllabus. I also forgot to give the mass in the problem, but it's easy to solve with it, as you can plug in Kepler's Third Law (p^2 = a^3).


Your Turn!!

Can you do spectroscopy questions please, because I need practice on that topic?

[Locoholic]

3. You're steps and the equations that you used were all correct, so nice job with that. This was really hard because you had to incorporate a wide variety of formulas and equations, that some of which weren't on the syllabus. I also forgot to give the mass in the problem, but it's easy to solve with it, as you can plug in Kepler's Third Law (p^2 = a^3).


Your Turn!!

Can you do spectroscopy questions please, because I need practice on that topic?

Alright!

1. (Element spectra). What is the Balmer series? What is the Paschen series? How does Rydberg's constant relate to Balmer's constant? Calculate the wavelength of an absorption line of hydrogen using a corresponding integer value of 4.

2. (Spectral types). Which spectral type has more aluminum lines: A or G? Are more metallic stars cooler? Why or why not? Which spectral type has the least visible hydrogen lines, and why is this the case?

3. (EM Wavelengths). Calculate the peak wavelength emitted by a blackbody with a temperature of 30,000 K. What type of electromagnetic wavelength is this peak emission? Name 2 benefits of each of the following: radio astronomy, infrared astronomy, x-ray astronomy.

[AstroKing]

Lemme try my best on these because I'm not that great at Spectroscopy...

1. [hide]I just know that Balmer lines are for Hydrogen, plz help on the rest of the questions, sry[/hide]
2. [hide]I'm guessing A, because it has stronger hydrogen lines, and ionized metal lines compared to G. How do you do this specifically for Aluminum, and other metals? IDK about metallic stars (plz help), K has the least visible hydrogen lines, IDK why but because of my chart[/hide]
3. [hide]Using Wien's Law: 96.67 nm for peak wavelength, Ultraviolet Light. I'm not great at the benefits so can u plz share the answers to them below, and can u also share the answer to benefits for (Infrared, X-Ray, Visible, UV, and Optical and Radio) please? Lemme try these... Infrared: emissions from dust grains that absorb visible light and are light, stellar nebula consisting of low-temperature gas and dust, clouds dust and heat, view star-forming regions and nebulae better. Radio: cosmic background, black holes?, X-Ray: gaseous remains of supernova remnants, propagating shock wave from supernova explosions, black holes/accretion disk, hot regions of gas]
Plz check these, and plz tell the correct answer for the ones that are missing or wrong.

Thx in advance!!

[IHateClouds]

About my cheat sheet, that's a question you should ask in a Private Message. I don't think my coaches would let me share a preview of my cheat sheet tho, so sorry . But I can tell you that I use size 3 Helvetica font with 0.25 margins, a page of words, and a page of images.

w u t.
just wut.

Also, how do you guys format your cheatsheets? Can I see a preview of your cheatsheet, to check if the formatting of my cheatsheet is alright, if that's allowed?

for all my events i do size four cabin, .05inch margins (lol i need to go to a specific printer than shrinks text for you to get this small of a margin...) and for reach i have about 3/4 side of images since its not one of my main events, but normally i just describe any images i need. i do every object in the same order as the rules and highlight each constellation group thingy the same color. i also like to use bolding and underlining to organize info

uhm maybe i shouldnt be posting a preview of my cheat sheet b u t im kinda trash at reach sooooo. (honestly i did blur it but it came out a lot blurrier from resizing it i probably did it wrong lol.)

[Locoholic]

Lemme try my best on these because I'm not that great at Spectroscopy...

1. [hide]I just know that Balmer lines are for Hydrogen, plz help on the rest of the questions, sry[/hide]
2. [hide]I'm guessing A, because it has stronger hydrogen lines, and ionized metal lines compared to G. How do you do this specifically for Aluminum, and other metals? IDK about metallic stars (plz help), K has the least visible hydrogen lines, IDK why but because of my chart[/hide]
3. [hide]Using Wien's Law: 96.67 nm for peak wavelength, Ultraviolet Light. I'm not great at the benefits so can u plz share the answers to them below, and can u also share the answer to benefits for (Infrared, X-Ray, Visible, UV, and Optical and Radio) please? Lemme try these... Infrared: emissions from dust grains that absorb visible light and are light, stellar nebula consisting of low-temperature gas and dust, clouds dust and heat, view star-forming regions and nebulae better. Radio: cosmic background, black holes?, X-Ray: gaseous remains of supernova remnants, propagating shock wave from supernova explosions, black holes/accretion disk, hot regions of gas]
Plz check these, and plz tell the correct answer for the ones that are missing or wrong.

Thx in advance!!

Your hide didn’t work for some reason (or maybe it just doesn’t show up for me). I recommend using the spoiler button instead because it’s more reliable.

For 1, The Balmer series is for hydrogen primarily in visible light, while the Paschen series is primarily in infrared. The Rydberg constant is 4 divided by Balmer’s constant. For the last question, you use the Balmer formula to get 486 nm. The Balmer formula equates the wavelength with B (Balmer’s constant) times (integer^2/(integer^2 - 4)). In this case the integer was 4, so you just had to plug it into the equation. They shouldn’t really ask about this at states/regionals, but I just wanted to provide a challenge.

2. Metal lines are actually characteristic of cooler stars, which makes the answer actually G. I just used aluminum because it is a metal. Metallic stars are cooler because metals tend to emit cooler wavelengths (reddish). Actually, O has the least visible Hydrogen lines because all of the hydrogen tends to be ionized and that stops atoms from emitting hydrogen absorption lines.

3. You’re right about everything you answered! For your general question, I’d recommend questioning the forum dedicated to RFTS rather than question marathons. I’d just look up [*insert wavelength here* astronomy] and see what benefits there are (I’m too lazy to give you all of them rn tho sry)



Anyways... your turn to ask questions!

[AstroKing]

Sorry, I was unactive for a while, I was pretty busy...
These questions will be pretty short and will be about DSO's


1. Which DSO's contain Supermassive Black Holes in the center of them?
2. This DSO's nickname is Gum 64, name 2 other nicknames of the DSO, and the distance to this DSO.
3. What percent of the size of the Milky Way is M104? Name a nickname for this DSO.