Wednesday, February 08, 2006

It's gonna be a bright sun shiney day

"I can see clearly now the rain has come....." - Not the most favourite song, or sentiment for an Astronomer. Yes, as you can guess, weather has been pretty poor for a long time. The last partially clear nightI got in my neck of the woods was nearly one and half weeks ago. Tomorrow, so they say on the weather report, and possibly up to Friday it's meant to be sunny. Rejoice! Weather it'll remain clear during the night remains to be seen, but one thing is for certain, it's turning cold once again. Of course at this point those of you reading this on the east coast of the USA are both laughing and mummbling, "you don't have a clue what cold weather is, buddy," and to that I'd agree! We think it gets cold here in Britain when it hits -2 degree's C at night but wait till you hit parts of the north eastern sea board of the USA. Oooohhh, now there it gets a little more than chilly. Yikes.

Tonight's Astronomy Diploma class at UCL was pretty interesting. We briefly covered detached and semi-detached binaries, Roche lobes and material transference between binary stars. We also learned about quasars, active galactic nuclei, Seyfert galaxies, black holes and revised knowledge from previous lectures about differnet forms of radiation emission related to each object we studied, i.e. cyclotron and synchrotron radiation, thermal emission, compton radiation and reverse compton radiation.

There was an interest question which came up in class tonight. "Why do neutron stars have a magnetic field?" Unfortunately we didn't get a solid answer to that question, but my guess is that all stars have some amount of ionized gas surrounding them and in them. By it's nature ionized gas has an inherent magnetic field. Big stars have a very large surface area so the magnetic field is spread out and thus moderately weak. On the other hand, Neutron stars are very small object, typically the size of the planet Earth and even smaller, possibily the size of a moderate city on Earth. This creates a much more compact surface area forcing the magnetic fields in the ionized gases to be much more closely associated, thus greatly increasing the magnetic field which for Neutron stars can run in to billions of Gauss. That's my theory anyway, but I'd like to find out if that's indeed true or if I'm totally barking up the wrong tree.


At Wed Feb 08, 01:32:00 am UTC, Blogger ~Z~ said...

Are the clouds ever going to go away?

At Wed Feb 08, 04:45:00 am UTC, Blogger Tag said...

Cold is cold...when them toes turn to cubes, it's just best to go with the flow. Our weather hasn't been too kind either.

As for your theory, sounds like a plausible reason - though I am not qualified to tell you right or wrong.


At Wed Feb 08, 07:25:00 am UTC, Anonymous Mark Garth said...

You mean Londoners think it's cold at -2. It was -7 when I went to see my elderly mother in the North West (UK) and she just said, what do you expect for winter! Anyway, back to London and I had a pretty good view of Jupiter at 0430 this morning with 4 moons in clear view. Bring on the clear skies.

At Wed Feb 08, 10:31:00 am UTC, Blogger Kaustav said...

Cold is certainly cold! I sometimes wonder how CCD camera's feel when their lords and masters cruelly cool them down to -40 degree's Celsius. There should be some sort of authority to report such heinous crimes to! LOL ;-)

Mark Garth:
04.30am! Man that's dedicated. I've been planning my first ever early morning session for a while but the ruddy London weather always beats me to it. Some clear nights coming up (I hope!) so lets see if I can fit in a Jupiter viewing before I head out to work in the morning. That would be fabulous! Do you post your images on the web anywhere? If so, what's the URL? Feel free to hyperlink to them via your comments on here.

At Wed Feb 08, 01:05:00 pm UTC, Anonymous Mark Garth said...

Not yet, I've only just bought a Meade LPI and am still getting to grips with it! I also need to buy an adaptor for my Canon EOS 350D. Astrophotography/imaging is something I need to spend more time on, but not at 0430 :-)

At Wed Feb 08, 03:25:00 pm UTC, Blogger Kaustav said...

Cool, my other half recently got a new Canon 350D and at Astrofest last weekend I bought an eye piece projection adapter for my Meade ETX105. I also have a normal pass through adatper for photography without an eyepiece and a piggy back bracket for taking wide field photos. Can't wait to try all three things out, though I suspect I will begin by using the piggy back method. I'm not looking forward to focusing using this set up. Where as the Canon 20Da has been specially adapted to allow you to view a real time view of the image through the lens on the backscreen, the 350D doesn't allow for this. I suspect there will be a lot of back and forth going on between taking test shots, downloading them to the PC and checking to see if focus is sharp. Ah, what joy to do when it's bloomin' freezing outside! Happy joy.

Let me know how you get on with you 350D astrophotography attempts.

At Wed Feb 08, 03:54:00 pm UTC, Anonymous Mark Garth said...

Which adaptor have you got for the 350D?
The reason I went for an LPI was to help with the focussing, although it's still a trial and error process, but at least you can monitor it real time on a PC. I use an 8" Meade LX90 and can't fault it.

At Wed Feb 08, 05:09:00 pm UTC, Blogger Kaustav said...

These are the items I got for my Meade ETX105:

Basic eyepiece projector.

ETX Camera support. There is an LX equivalent on their web site.

I also got the T-adapter specially for the Canon DSLR series and a focusing adapter which is the bring between the T-ring and the camera body. i.e. you thread the focus adapter in the ETX and thread the other end of it in the T-Ring, and T-ring attaches on to the Canon 350D.

Ya gets me, Jimmy?

At Thu Feb 09, 12:29:00 am UTC, Anonymous Tom said...

Our weather has been terrible for astronomy for a long time too, but not too cold. It is bound to improve here and there, it just has to.

At Fri Feb 10, 10:11:00 am UTC, Anonymous Anonymous said...

Neutron Stars? The answer is perhaps here. . .

At Fri Feb 10, 01:06:00 pm UTC, Blogger Kaustav said...

I've done some more reading up on this question about why Neutron stars have a strong magnetic field. It turns out that my guess was partially correct but there's much more to the story.

The internal structure of a neutron star is made up of various layers. These are comprised of (from the top layer moving downwards towards the core):

- Outer crust (nuclei, electrons)
- Inner crust (nuclei, electrons and Superfluid neutron)
- Normal Neutron layer
- Inner core (superfluid neutrons, superconducting protons and electrons)

Is is the precense of the protons and electrons in the core and upper layers which cause the strong magnetic field in a neutron star.

And there you have the answer!

At Sun Feb 12, 10:53:00 pm UTC, Anonymous Anonymous said...

That's it Kaustav - 'Atmosphere' and superconducting core dynamo.

You might also be interested in looking at which describes the next step - quark stars. Makes you wonder what really happens behind the event horizon of a Black Hole.

By the way - where have all the old (local) quasars gone??

At Mon Feb 13, 10:30:00 am UTC, Blogger Kaustav said...

Dear Anonymous,
Thanks for the response. Re-assuring to know that I'm not totally stabbing in the dark, although I just realised that phrase could be turned into a very bad astronomers joke ;-) HAR HAR!
The link you sent it really interesting. Funnily enough my astronomy lecturer at UCL also sent me the same URL this morning in his email. Great minds think alike, huh? ;-)

As for your questiom, I really don't know. I can try and put some simple common sense "facts" together and only surmise what sounds logical, so here's my take on your question. Please let me know what you think.

Supermassive black holes that power quasars are still around. They're more massive than ever, thanks to the gas that they are accreting. However, gas is being fed into them at a much lower rate compared to in the past. Eleven or twelve billion years ago, galaxies interacted more frequently than they do at present and during those mergers and close encounters between galaxies, tidal forces increased the rate at which gas was fed into the central black holes. Currently, gas is being accreted by black holes at a much lower rate, resulting in galactic nuclei which are much lower in luminosity than they were in the past and hence you're not getting so many quasars anymore. Hmmm, sounds sort of sensible, but I'd like to know what the professionals think.


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