Astronomy C

[Unome]

If you guys don't mind me taking this conversation to more technical areas, there are a few inconsistencies regarding DSO's that I'd like to bring up.

ESO 137-001, for example, has a different constellation depending on the source.

[*]https://en.wikipedia.org/wiki/ESO_137-001
[*]http://chandra.harvard.edu/photo/2014/eso137/

Chandra says Norma while Wikipedia says Triangulum Australe.


In addition, I've also had some difficulties determining the mass for IC 10.

[*]https://arxiv.org/pdf/1708.03634.pdf
[*]https://arxiv.org/pdf/1611.08611.pdf

The first source is a paper that I found online describing the SFR and abundance of WR stars in IC 10. It cites the mass of IC 10 as 7.5 x 10^7 M☉ (2012)

The second source is the paper mentioned in the Chandra article for IC 10. It cites the mass of IC 10 as 2 x 10^7 M☉ (1997).


Any suggestions for what to do?

For the first, check papers for exact location and derive the constellation yourself (assuming the papers don't have diverging locations). For the second, there's not much you can do - mass of distributed objects is mostly guesstimate anyway.

[syo_astro]

In addition, I've also had some difficulties determining the mass for IC 10.

For the first, check papers for exact location and derive the constellation yourself (assuming the papers don't have diverging locations). For the second, there's not much you can do - mass of distributed objects is mostly guesstimate anyway.

I get what you mean by "guesstimate"...but semantics! Mass estimates *can be* quite inaccurate, but there's good reason: It's really hard to estimate mass, and it's often an indirect measurement requiring assumptions (e.g. All the mass in a region is Hydrogen, things are spherical, etc). That said, there are some more direct methods that are actually pretty good (but don't have the time to get into that detail). Reading methodology/observations/analysis in papers is also quite difficult...

Usually what matters most for having numbers on hand is having the right order of magnitude-ish (depending on the test writer). Many should give values, though some cases you might still need to know the gist (e.g. the mass of a galaxy cluster vs. a galaxy). Is there a reason you think you need to have all the exact masses @Simulacrum?

[Simulacrum]

I'm fine with both masses having the same order of magnitude, but it still bothers me when I'm filling in data tables and have two values. I'm generally inclined to use the more recent value if at all possible.

The difference in constellations does bother me more, since I usually go with the Chandra data. Outside of Chandra, though, most sources seem to agree on Triangulum Australe.

https://www.eso.org/public/usa/images/eso1437c/

I think I'll just put down both constellations for now.

[PM2017]

Many should give values, though some cases you might still need to know the gist (e.g. the mass of a galaxy cluster vs. a galaxy). Is there a reason you think you need to have all the exact masses @Simulacrum?

Simulacrum and I had a few bad experiences during our first year on the team with tests asking extremely particular questions, for which we have given an answer we found from one source, only to have it marked wrong because the test writer presumably used a different source.

Since then, we'd decided to err a bit on the paranoid side, and it gets a bit frustrating when these values are ambiguous. This specific example, however, doesn't seem like something ESes would ask the exact mass for. If they do, then I have no words...

[ET2020]

Do you have to show work on the calculations parts of most tests? I'm thinking of making a program on my computer to do the math problems for me, to save time and take out human error, but I don't know how the test writer will feel about a bunch of correct answers with no work.

[lumosityfan]

Do you have to show work on the calculations parts of most tests? I'm thinking of making a program on my computer to do the math problems for me, to save time and take out human error, but I don't know how the test writer will feel about a bunch of correct answers with no work.

Well, I don't believe the rules require it plus at least in my experience as an event supervisor, I'm usually too worried about trying to grade all the tests to worry about work, so imo I would say no? I guess? I say that because other supervisors might be more nit-picky about such habits. Also, it's usually a good idea to still go through the methods because those methods can also be applied to relevant astronomical objects, details of which could (and probably will) be asked about in other problems (particularly DSOs where these concepts will be applied).

[syo_astro]

Do you have to show work on the calculations parts of most tests? I'm thinking of making a program on my computer to do the math problems for me, to save time and take out human error, but I don't know how the test writer will feel about a bunch of correct answers with no work.

Well, I don't believe the rules require it plus at least in my experience as an event supervisor, I'm usually too worried about trying to grade all the tests to worry about work, so imo I would say no? I guess? I say that because other supervisors might be more nit-picky about such habits. Also, it's usually a good idea to still go through the methods because those methods can also be applied to relevant astronomical objects, details of which could (and probably will) be asked about in other problems (particularly DSOs where these concepts will be applied).

I have seen both types of tests. I would say make the programs anyway if they help you, but maybe practice calculating both by hand and with your calculator (which is pretty common when doing math anyway, helps as lumo described!).

Edit: @PM2017/Simulacrum: Ah...yeah, there's no good solution then. In those cases I agree it's probably best to just note all the values with references, try to ask the proctor on the spot, and hope for the best >.>.

[biz11]

Does anyone know where the 500,000 number for antennae galaxy size comes from? I keep seeing 350,000 ly in most places, but I can't figure out where they're coming from or anything about which to use.

[inprogress]

How do I compile my DSO notes? Do I basically copy paste every detail from Wikipedia...? It just takes a lot of time and I feel like a lot of information is unnecessary...I'm having difficulty figuring out what is considered "important" or not. Like the history of it?

Should I also spend time looking for images at different wavelengths? And images of supernovae that occurred in a galaxy?

[syo_astro]

Does anyone know where the 500,000 number for antennae galaxy size comes from? I keep seeing 350,000 ly in most places, but I can't figure out where they're coming from or anything about which to use.

What's the issue with the numbers? Does one come from Wikipedia? If it does, you may be able to check their sources / citations (always preferred to only noting a number and that it comes from Wiki).

How do I compile my DSO notes? Do I basically copy paste every detail from Wikipedia...? It just takes a lot of time and I feel like a lot of information is unnecessary...I'm having difficulty figuring out what is considered "important" or not. Like the history of it?

Should I also spend time looking for images at different wavelengths? And images of supernovae that occurred in a galaxy?

This was somewhat answered in this thread, so double check that. Another thing that wasn't said is the scioly.org wiki topic page: https://scioly.org/wiki/index.php/Astronomy. If you go to "Deep Space Objects" (should be Deep Sky Objects...), then you should see another link with relevant info.

Next, Wikipedia is an okay place to start, but copying (even resummarizing) every detail won't always help on the spot. It depends on the test / writer, but you should use other sources. Usually they are on the scioly wiki, soinc.org and the annual Chandra webinars. One thing is you're allowed a laptop, but the event is still science, so all the info. at your fingertips may not help you understand concepts or answer questions (not meant patronizingly, just a common misconception).

As for what's important: Different people may give answers. You can check different tests on the old/new test exchange to see what I mean (luckily past years have different topics, so you won't be using up any proper practice tests). Some say "have all the basic info from all sources, like constellations, magnitudes, etc". What I'd say is that DSOs *also* help you learn and apply concepts. If you can apply or know where to find the info for every prior part of the rules for every DSO (ignoring obviously irrelevant parts, which is case by case), then I'd say that's everything "important"...so yes, a lot. Unless you're fairly experienced, most pace their work and split with a partner.

As for images, yes, all the images (they're pretty too!). Hope this helps, please keep questions coming if that was confusing!