Astronomy C

[Smithy0013]

http://scioly.org/wiki/index.php/Variable_Stars
So on this page it says that Cepheids are greater than 1 day but I found a site that looks reputable claiming that anomalous Cepheids can have periods of about a third of a day. Error on the wiki or am I missing something?

[syo_astro]

http://scioly.org/wiki/index.php/Variable_Stars
So on this page it says that Cepheids are greater than 1 day but I found a site that looks reputable claiming that anomalous Cepheids can have periods of about a third of a day. Error on the wiki or am I missing something?

There are A LOT of cepheids. Classical Cepheids have a decent range of periods, and Type II Cepheids have many subtypes that actually range from 1 to many days. I have notes saying that Anomalous Cepheids are relatively shorter in period, so that makes sense (I can't exactly remember what differentiates them and RR Lyrae, but they are definitely short in period). Hope that clears things up!

[Smithy0013]

ehhh kindof. I'd just be worried if we have to identify the two based on period of a light curve. Oh well theres probably some other way of differentiating RR Lyrae from Cepheids. Off to do more research :p

[AnthonyHeu]

Does anyone know if there is an answer key for AlphaTauri's practice test?

[AlphaTauri]

I had the key mostly done at some point, but I uh, don't know where it went... I'll try to redo it within the next month or so (after this invitational I've got coming up).

[SuperAJ]

I hate the long tests that do not pose difficult questions, but are big in terms of volume. This sometimes hurts the person that writes out long and thought-out responses to questions.

[nomynameisnotkevin]

I had the key mostly done at some point, but I uh, don't know where it went... I'll try to redo it within the next month or so (after this invitational I've got coming up).

That would be much appreciated, as there are some fantastic questions on there that I really wished I knew

[Schrodingerscat]

Has anyone found a good all-in-one yet highly detailed HR diagram? The only ones I have ever been able to find might show a particular part very well, but completely neglect other parts.

[syo_astro]

Has anyone found a good all-in-one yet highly detailed HR diagram? The only ones I have ever been able to find might show a particular part very well, but completely neglect other parts.

Personally I haven't really found any "all-in-one" diagrams. I'd recommend just having it all in your binder/laptop just in case. So that can be focused on variable stars, stellar evolution, color-magnitude diagrams for clusters, varying units for axes, focused on different mass ranges/sections, and whatever other labels you could think up or find. Hope that helps!

[hexagonaria]

Hi people.
So, I understand how astronomical coordinates are written as right ascension and declination, but I'm confused about how they can actually be used to locate DSOs. I mean, the Earth rotates on its axis every 24 hours, and orbits around the sun approximately once a year. So, wouldn't the right ascension of an object in space be constantly changing throughout the day and the year? So if I told you to find an object at RA: 02h 19m 20.70s and DEC: -02° 58' 39.51" , when would you take that measurement?