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Old 07-12-2019, 01:59 PM
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Merlin66 (Ken)
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Eta Carinae activity!

Enhanced gamma ray activity:
http://www.astronomerstelegram.org/?read=13329
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Old 10-12-2019, 10:09 AM
hamishbarker
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I need to get my L200 up and running so as to start taking E-car spectra in time to get a regular series pre-, during- and post-periastron (coming in febuary). Hopefully something spectrographically exciting will happen as part of the periastron. The question is which lines to observe? i only have a 600lpmm grating for the L200.

I read this very interesting paper re a proposed "natural coronagraph" of dust, which the authors propose is a blob of dust which may be dissipating and may result in the homunculus nebula being invisible by circa 2030.

https://arxiv.org/pdf/1901.00531.pdf


My CGEM mount which I bought from Logan may be coming from australia (my sister is coming to visit) this weekend. Then once that is operational, there will probably be a need to modify my dob's tube (which will be pressed into equatorial mount service until I build the 10"f5 mirror into a newtonian) to achieve sufficient back focus.
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Old 10-12-2019, 01:17 PM
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Merlin66 (Ken)
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Hamish,
It would be good to have you assisting with Eta Car observations.
The SASER group have been targeting the following wavelengths (at R=10000) for a ProAm campaign.
4686 A
5876 A
and 6347 A.

Within the 600 l/mm you'll at least pick up any major activity....

Drop me an email for further details.
ken
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Old 11-12-2019, 06:12 AM
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I am also preparing spectrograph fot eta event.
Especially because the company I work for is in serious trouble, and I may find myself in retirement sooner than expected.... so I will hopefully have much more free time for astronomy.

At this moment I am thinking of my Hartridge spectrometer, coupled with optical cable to C11.
Another one is Star analyser (100l/mm) mounted inside c11.

3D printer will come here very handy...
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Old 11-12-2019, 08:09 AM
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Merlin66 (Ken)
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Sounds good!

It has been said that there's only two astronomical objects worth observing - Eta Car and the rest!
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Old 11-12-2019, 08:36 AM
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Sounds like a great NACAA paper in the making!


http://www.iceinspace.com.au/forum/s...50#post1456250
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Old 20-12-2019, 02:48 PM
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I imaged Eta Car last night and, well, there seems to be something a bit strange going on although I can't quite put my finger on it.

Seriously though I'm looking forward to another periastron passage and it's possible that by then I may have some heavier artillery than before.

Cheers -
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Old 20-12-2019, 03:04 PM
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Merlin66 (Ken)
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Rob,
To much Xmas celebration?
Ken
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Old 20-12-2019, 03:22 PM
Rob_K
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Quote:
Originally Posted by Merlin66 View Post
Rob,
To much Xmas celebration?
Ken
Haha, I wish Ken! Last night I introduced a new lens into my nova search, 50mm f/1.4, to replace the 55mm in the awful 55-200 zoom lens that I had. To blink it in Photoshop I had to transform an earlier shot to the new scale, but before that it made this pretty pattern when first overlaid, and I embellished it!

Xmas celebration would have been a much better story!

Cheers -
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Old 20-12-2019, 10:42 PM
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Hi All,

Like a great number of other amateurs, I've been keeping one eye on Eta Carinae ever since it broached naked-eye visibility again.

The events to which the telegram refer are very likely due to interactions between the winds between the two stars as they approach periastron (ie one solar-wind colliding with the other). These events are really largely observable at very high energies (hard x-ray & gamma rays). The cause of these events is almost certainly extrinsic to the stars themselves (external). Sure, take spectra, but don't be too disappointed if it shows little or nothing.

Eta has been slowly climbing in visual magnitude for a long time but its output measured over all wavelengths (bolometric magnitude) is nearly unchanged for quite a while (decades). When I did an estimate the other night, I put it at 4.4 and this has been pretty constant for the last several years.

So while the star's(s) overall output is fairly constant, what has changed is the wavelengths of peak emission. The currently accepted explanation, or at least the "best model" is that the Homunculus Nebula, likely ejected during the 1890s event has expanded sufficiently and lowered in density and temperature sufficiently that the star itself is shining "out" of the nebula as opposed to "through" the nebula (ie light from the star(s) absorbed by the nebula and then re-emitted at a different wavelengths). While the visual output has been climbing, the infra-red emission has been generally falling. That is similarly reflected in the changing nature in the appearance of the homunculus at visual wavelengths that has been apparent over the last 30-40 years -- more particularity during the last 20 years.

It is all rather intriguing, but I wouldn't be reading too much into its increasing brightness at visual magnitudes which is most likely due to the binary "clearing-out" their immediate neighbourhood(s).

That's not to say: "nothing is about to happen here, return to your beds good citizens". It might well do in a way that isn't predictable, but the current observed changes don't actually say much about the internal composition or structure of the stars where the "real action" will take place when/if does go kahblooie.

Best,

L.

Last edited by ngcles; 21-12-2019 at 12:16 AM.
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Old 21-12-2019, 08:56 PM
hamishbarker
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Quote:
Originally Posted by bojan View Post
I am also preparing spectrograph fot eta event.
Especially because the company I work for is in serious trouble, and I may find myself in retirement sooner than expected.... so I will hopefully have much more free time for astronomy.

At this moment I am thinking of my Hartridge spectrometer, coupled with optical cable to C11.
Another one is Star analyser (100l/mm) mounted inside c11.

3D printer will come here very handy...

for star analyser: I have had some good results using a SA100 and wedge prism set partly inside/downstream of an orion thin off axis guider. I had to do this because with the SA100 upstream of the off axis guider, the dispersion gets excessive (and needlessly dim, lowering S/N ratio - I was trying to image last years nova in the SMC which was getting faint).



lots of mucking around was required to get the guide camera and dslr parfocal.



In the end I had to just wrap the SA100/prism with rolled up magazine pages to bulk out to the diameter of a 10mm long T thread spacer. 3d printing would have been handy!


Now I have the camera in good focus on my L200, and also have rigged up power for the calibration lamp, and my (ex Logan Nicholson) secondhand CGEM mount working. The only part of the puzzle remaining is to move the mirror cell of my 200mm f6 a bit up the tube, as I can't get sufficient back focus to focus on the L200 slit. Now that it's the xmas break I have a chance.


And then there's the exciting developments with Betelgeuse getting a bit dimmer than usual which I should get spectra for.
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Old 22-12-2019, 12:03 AM
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The star is indeed about +4.4 but appears very reddish like Betelgeuse.
Probably due to the dust cloud like the Sun is now around Sydney in the smoke cloud.

It would be nice that it brightens up to mag 0 in the upcoming decades, like in 1843, but that is unlikely.


The star is much hotter and has a luminosity of 5 million times the Sun according to the largest online astronomy textbook.

When unobscured, it should be mag -0.3 seen from here at 7500 light years, slightly brighter than Alpha Centauri. So it is darkened almost 100 times.
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Old 28-02-2020, 07:05 AM
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My cousins were visiting and last night was clear here in Nelson so we started with the lovely young crescent moon, and via a few other stops (orion, tuc 47 , tarantula) we arrrived at Eta carinae.



And wow, the seeing was exceptional (and my telescope collimation was for once good). The homunculus nebula was clearly visible around and to one side of the star). I've never seen it so clearly. I agree, it seemed distinctly red. Which I though was a bit odd (not having read skysurfer and ngcles posts prior to the observation), since it is a very massive blue star, and had to recheck that I was really pointing the telescope in the right direction and not showing my cousins something completely wrong! So I'm glad to read that others think it looks red.




Haven't taken any spectra of it though. :-(
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