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First light for ES EP duo - Omicron-2 Eridani

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#1 greyfox

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Posted 31 January 2013 - 02:59 AM

Hey everybody:

So its been two weeks since I received my ES 82 degree 4.7mm and 11mm, eyepieces I specifically purchased to up my double star game. The sky finally cleared tonight, so I setup the OXLT 102ED for some casual double star observations.

First target was, quite naturally, Sirius. With the 24mm Pan Sirius was flaring, beach balling, and dancing like liquid. So the Pup was definitely out tonight. I decided I was determined to bag a white dwarf tonight, so I turned my scope to "Keid" for the very first time.

Lining up "Keid" in the finder and plopping in the 24mm Panoptic, I was given a fine view of a definitely orangish-red primary, and the white dwarf popped into view a couple seconds later. Easy. Now to pull apart the B-C pair, I plopped in my 11mm ES 82. First light for this eyepiece, which did NOT show the red dwarf, but the view was very nice just the same. So, in went the ES 4.7mm 82 degree, giving 191.5x Bringing the system into focus, I tracked the pair for a few minutes and let my eyes adjust to the scene. After a few minutes and a little averted vision, the red dwarf popped into the field of view, completing the triple! I tracked for a few more minutes, and the dim red dwarf went in and out of my vision. Definitely a tough catch at mag 10.2 in suburban skies....I'm satisfied! :)

I highly recommend this neat system while Orion and Eridanus are still up. A really nice description of the system is found in Burnham's Celestial Handbook. Have a good evening!

Brad

#2 WRAK

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Posted 31 January 2013 - 03:57 AM

Brad, sounds very interesting. I am not sure about the WDS data concerning Keid, missing especially the B-C data it seems. Some interpretation would mean 3.9" separation with +9.7/11.47mag but you mention +10.2mag?
I fear anyway Keid is to low for me for any good observation, but I can try if the weather clears.
Wilfried

#3 greyfox

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Posted 31 January 2013 - 01:23 PM

Wilifred:

Currently, the B-C pair has just over a 9" seperation. They just turned the end of a long ellipse and are starting to close up again, though they will be 8"-9" during our lifetimes. The real trick with this system is just seeing the red dwarf component. Burnhams lists the components as A) 4.48 B) 9.7 C) 10.8 WDS seems to indicate 10.02 for "B" and 11.47 for "C". I think my 10.2 comment was a bit spurious, I think somewhere between 10 and 11 is more likely for "C". Also, I think the fact that its a red dwarf complicates the observation, since its outgoing light is feeble to begin with. I didn't see anything until the power went up and steady concentration was used.

Good luck with the observation....its a very neat system for sure. I agree with Burnham, the "B" star is definitely a fairly easy white dwarf. I also found the color of the primary (K1 V?) itself to be quite a fine yellow-orange.

Brad

#4 Achernar

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Posted 01 February 2013 - 10:15 AM

Congratulations, 40 Eridani is one of my favorite triple stars because through a 10-inch it's easy to see the deep yellow, white and red colors of the stars. Doubly so becuse 40 Eridani B is the only white dwarf that is easy to see in amatuer telescopes, especially small telescopes. It's also the first white dwarf to be discovered.

Taras

#5 fred1871

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Posted 01 February 2013 - 06:41 PM

Agreed, it's a fine object, and although you might need a 10-inch to see colour in the faintest star, the red dwarf, I could see the contrast of the bluish-white white dwarf against the orange-yellow primary, viewing it with a 7-inch refractor. Only 100x was needed for a neat view. The red dwarf was simply "dull" without specific colour tone - a ten-inch gives twice the light, hence Taras seeing colour in it as well.

A very fine triple - Wilfried, the Declination is not quite 8 degrees south, so it should be possible for you unless you're above the Arctic Circle. Struve apparently saw it. Ummm... what's the latitude of Poulkova?

#6 WRAK

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Posted 02 February 2013 - 04:13 AM

Fred, you are right - in my current frame of view and local time of 8pm it is above 30° altitude and therefore for a wide double high enough. Only problem is the weather not permitting me any observations now and very soon it will be too low for me. Poulkova should be about 60° north.
Wilfried






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