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New Horizons "stellar" course?



 
 
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  #41  
Old January 9th 19, 02:10 PM posted to sci.astro.amateur
Martin Brown[_3_]
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Posts: 189
Default New Horizons "stellar" course?

On 09/01/2019 12:28, JBI wrote:
On 1/9/19 6:50 AM, Martin Brown wrote:
On 09/01/2019 01:19, JBI wrote:
On 1/8/19 6:09 PM, Thomas 'PointedEars' Lahn wrote: JBI wrote:
* ^^^


* there doesn't give me much hope unless a super telescope is
constructed
* in space.
*
* You do not need large telescopes for good resolution if you have
several
* small ones and can do interferometry:
*
* https://en.wikipedia.org/wiki/Astronomical_interferometer

I realize both Hubble and interferometers have done a lot for
astronomy, but I wonder when the next giant step in resolution will
be.* As far as I know, there are no interferometer set ups in space.
Even doing what they do on Earth, without the atmosphere, I would
think they would do much better.


The optical interferometer setups on Earth use closure phases and
closure amplitudes to get good observables despite the atmosphere
(using the same methods as radio astronomers do - indeed mostly led by
them).

Obviously it would be better not to have corrupted raw data.

COAST was one of the very early ones and did some imaging of Betelgeuse

https://www.mrao.cam.ac.uk/outreach/...pergiants02-04


General introduction and links to other optical interferometers he
https://www.mrao.cam.ac.uk/outreach/...escopes/coast/


Interesting.* I guess this is how they're going to do it then, with
larger and larger interferometers in the future.* Did they ever try
imaging something much closer, like say Pluto, just to confirm the
resolution increase?* Maybe deemed irrelevant and a waste of time.* It
does seem to clearly show increased detail on the supergiant surfaces.


They tend to go after fairly bright near equal tight double stars and
supergiants since you need a lot of signal to noise for beam splitting.

Pluto is way too dim for interferometry at present.

Amazingly the very first optical interferometry over a 10m baseline was
done using a steel framed periscope mounted on the Mount Wilson scope in
1920 by the brilliant experimentalist Michelson & Pease.

https://www.atticusrarebooks.com/pag...al-journal-vol

It wasn't surpassed until the 1960's when Hanbury-Brown and Twiss at
Jodrell Bank built the intensity interferometer using two old WWII
searchlight parabolic mirrors and photomultipliers. His book "The
Intensity Interferometer" is an interesting if mathematical read. It is
a fairly rare book but some observatory technical libraries have a copy.

https://www.amazon.co.uk/Intensity-I...Interferometer

A much improved version was built are Narrabi (sp?) in Australia.

--
Regards,
Martin Brown
  #42  
Old January 9th 19, 07:26 PM posted to sci.astro.amateur
JBI
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Posts: 11
Default New Horizons "stellar" course?

On 1/9/19 7:19 AM, wrote:
On Tuesday, January 8, 2019 at 4:48:49 PM UTC-5, JBI wrote:
On 1/8/19 11:22 AM, JBI wrote:
On 1/8/19 8:29 AM, wsnell01 wrote:
On Friday, January 4, 2019 at 8:51:04 AM UTC-5, JBI wrote:
Cannot find this information anywhere, but curious where New Horizons
would be heading in the long term, in other words what star? And also
are there any more visits to other objects planned besides the latest?
Thank you.

Here is a link with some cool info and other links about where the
five spacecraft are going:

https://space.stackexchange.com/ques...imately-headed



Yes, I was aware of the Voyagers and others, but was a bit off on the
distance.Â* I thought Voyager I was a little further along than it was. I
was thinking one light day, but about 3/4 of that at roughly 17 light
hours.Â* Still interesting to think about and ponder the vast stellar
distances.Â* At least it makes it a bit easier to put such numbers in
terms common folks can better understand.Â* Thanks for sharing.


I also hope to live to see a reasonable resolution of a large star such
as Betelgeuse. Noting the basically poor resolution of Hubble of Pluto
until New Horizons got there doesn't give me much hope unless a super
telescope is constructed in space. Always possible, but I probably
won't live to see it.


Not as detailed as you want, but here are some articles with pics:

https://astrobob.areavoices.com/2014...ks-you-betcha/

https://www.popularmechanics.com/spa...un-betelgeuse/


By the way, I wonder what's going on with R Doradus with its "spiked"
appearance. I wonder if it's the nature of the IR band causing it, or
maybe that's how it really appears? Strange.
  #43  
Old January 9th 19, 07:39 PM posted to sci.astro.amateur
Chris L Peterson
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Posts: 10,007
Default New Horizons "stellar" course?

On Wed, 9 Jan 2019 13:26:49 -0500, JBI wrote:

By the way, I wonder what's going on with R Doradus with its "spiked"
appearance. I wonder if it's the nature of the IR band causing it, or
maybe that's how it really appears? Strange.


It's simply an artifact of the mathematical process used to
reconstruct a spatial image from the raw interferometric data.
  #44  
Old January 9th 19, 08:26 PM posted to sci.astro.amateur
Martin Brown[_3_]
external usenet poster
 
Posts: 189
Default New Horizons "stellar" course?

On 09/01/2019 18:26, JBI wrote:
On 1/9/19 7:19 AM, wrote:
On Tuesday, January 8, 2019 at 4:48:49 PM UTC-5, JBI wrote:
On 1/8/19 11:22 AM, JBI wrote:
On 1/8/19 8:29 AM, wsnell01 wrote:
On Friday, January 4, 2019 at 8:51:04 AM UTC-5, JBI wrote:
Cannot find this information anywhere, but curious where New Horizons
would be heading in the long term, in other words what star? And also
are there any more visits to other objects planned besides the
latest?
Thank you.

Here is a link with some cool info and other links about where the
five spacecraft are going:

https://space.stackexchange.com/ques...imately-headed




Yes, I was aware of the Voyagers and others, but was a bit off on the
distance.Â* I thought Voyager I was a little further along than it
was. I
was thinking one light day, but about 3/4 of that at roughly 17 light
hours.Â* Still interesting to think about and ponder the vast stellar
distances.Â* At least it makes it a bit easier to put such numbers in
terms common folks can better understand.Â* Thanks for sharing.

I also hope to live to see a reasonable resolution of a large star such
as Betelgeuse.Â* Noting the basically poor resolution of Hubble of Pluto
until New Horizons got there doesn't give me much hope unless a super
telescope is constructed in space.Â* Always possible, but I probably
won't live to see it.


Not as detailed as you want, but here are some articles with pics:

https://astrobob.areavoices.com/2014...ks-you-betcha/


https://www.popularmechanics.com/spa...un-betelgeuse/



By the way, I wonder what's going on with R Doradus with its "spiked"
appearance.Â* I wonder if it's the nature of the IR band causing it, or
maybe that's how it really appears?Â* Strange.


It is the method used which is essentially a set of holes at carefully
chosen positions in a big mask across a large aperture.

The classic pattern for a small number of holes is Golumbs ruler which
allows the maximum number of unique baseline correlations to be measured
for a given number of ticks (in this case holes).

N baselines measured
2: 0 1 {0,1}
3: 0 1 3 {0,1,2,3}
4: 0 1 4 6 {0,1,2,3,4,5,6}

It is speckle imaging which is closer to aperture synthesis radio
astronomy than conventional optical imaging see for more details:

https://www.eso.org/public/usa/news/eso9706/

--
Regards,
Martin Brown
 




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