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Can blue stragglers be observed with an 8 incher?

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#1 theApex

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Posted 24 August 2019 - 05:09 AM

I was wondering just that: if I can point my C8 at, say, 47 Tucanae and pinpoint them through the EP.

Is that possible? Do they appear in any catalog or planetarium software?


Edited by theApex, 24 August 2019 - 01:13 PM.


#2 BQ Octantis

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Posted 24 August 2019 - 06:18 AM

I was wondering just that: if I can point my C8 at, say, 47 Tucanae and pinpoint them with my C8.

Is that possible? Do they appear in any catalog or planetarium software?

I captured one in 47 Tuc through my 7-in Mak:

 

https://www.cloudyni...-f15/?p=9090307

 

Not sure about a catalogue…

 

BQ



#3 Keith Rivich

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Posted 24 August 2019 - 08:28 AM

The short answer is yes, they can be observed with an 8". Larry Mitchell took an interest in stragglers and created a nice finder chart for the open cluster NGC7789 in Cass. We spent the better part of a night hunting them down, me with my 18" Larry with his 20". The toughest part was positively identifying them in such busy star fields.Puts your star hopping skills to the test. Much like seeing the planetary in m22. Another thing to consider is that they do not look blue, they are pretty much white. 

 

Not sure if a chart exist for 47 Tuc. 


Edited by Keith Rivich, 24 August 2019 - 08:48 AM.


#4 Mark SW

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Posted 24 August 2019 - 08:39 AM

"Google it. It will work."

Not my quote but seems to be a standard



#5 Keith Rivich

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Posted 24 August 2019 - 11:34 AM

I'll amend my post above: 

Blue stragglers in 47 Tuc *may* be visible in an 8". Found a diagram that shows, if accurate, the brightest stragglers are ~15th magnitude. Tough in an 8" but doable under good conditions. 

 

https://www.cfa.harv..._club/47Tuc.pdf



#6 theApex

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Posted 24 August 2019 - 01:14 PM

I captured one in 47 Tuc through my 7-in Mak:

 

https://www.cloudyni...-f15/?p=9090307

 

Not sure about a catalogue…

 

BQ

Nice! That's very blue - way more than I'd expect them to be!



#7 theApex

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Posted 24 August 2019 - 01:18 PM

The short answer is yes, they can be observed with an 8". Larry Mitchell took an interest in stragglers and created a nice finder chart for the open cluster NGC7789 in Cass. We spent the better part of a night hunting them down, me with my 18" Larry with his 20". The toughest part was positively identifying them in such busy star fields.Puts your star hopping skills to the test. Much like seeing the planetary in m22. Another thing to consider is that they do not look blue, they are pretty much white. 

 

Not sure if a chart exist for 47 Tuc. 

Wow! Even though NGC 7789 is too low in the horizon for my location, for the long run, is there any chance such chart could be shared online?

 

Edit: thanks a lot for the 47 Tuc diagram, Keith.

Now that it's rising higher and higher in the southeastern sky every night, I will certainly give it a go at a dark site; now, if only I could get hold of a chart...


Edited by theApex, 24 August 2019 - 01:25 PM.


#8 theApex

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Posted 24 August 2019 - 01:20 PM

"Google it. It will work."

Not my quote but seems to be a standard

??



#9 Keith Rivich

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Posted 24 August 2019 - 02:06 PM

Wow! Even though NGC 7789 is too low in the horizon for my location, for the long run, is there any chance such chart could be shared online?

 

Edit: thanks a lot for the 47 Tuc diagram, Keith.

Now that it's rising higher and higher in the southeastern sky every night, I will certainly give it a go at a dark site; now, if only I could get hold of a chart...

I’ll try and find the chart. 


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#10 BQ Octantis

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Posted 24 August 2019 - 05:43 PM

Nice! That's very blue - way more than I'd expect them to be!

I didn't see it through the eyepiece, but I wasn't looking for it—it was processing this image that made me aware of blue stragglers to begin with! 47 Tuc will be a convenient evening target again soon enough…

 

BQ



#11 Enkidu

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Posted 25 August 2019 - 01:36 AM

HR 7419 a mag 6.3 blue straggler (part of the Sirius supercluster), a few degrees west of eta Cygni and just ~190pc away. B-V index of 0 (white), but it should be visible in just about any instrument.


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#12 theApex

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Posted 25 August 2019 - 06:04 AM

Thanks for that. Though not in the open/globular cluster context I was hoping for, I'll certainly give it a go this week.

It's a pity that, after googling for it for the biggest chunk of an hour, I've come to realise information about it (and the supercluster) seems to be pretty scarce and dealt with nowhere but on the odd mention here on CN or scientific papers such as this "impossible-to-read-on-small-screens" paper:

https://iopscience.i...00465/fulltext/
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#13 Enkidu

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Posted 25 August 2019 - 06:57 AM

Thanks for that. Though not in the open/globular cluster context I was hoping for, I'll certainly give it a go this week.

It's a pity that, after googling for it for the biggest chunk of an hour, I've come to realise information about it (and the supercluster) seems to be pretty scarce and dealt with nowhere but on the odd mention here on CN or scientific papers such as this "impossible-to-read-on-small-screens" paper:

https://iopscience.i...00465/fulltext/

Agreed. Specialized research papers like these (for which I'm grateful) often aren’t synthesized into the bigger picture until writers (or scrappy collectives of amateur observers) fill the gap... Lots to discover, I find it thrilling to be honest!



#14 Keith Rivich

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Posted 25 August 2019 - 10:38 AM

I’ll try and find the chart. 

I talked to Larry Mitchell and when he gets back from vacation (British Isles) he will send me the 7789 charts. I will also ask him what sources he used to create the chart.


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#15 theApex

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Posted 25 August 2019 - 11:05 AM

Thanks for going the proverbial extra mile.



#16 Organic Astrochemist

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Posted 25 August 2019 - 11:47 PM

Thanks for that. Though not in the open/globular cluster context I was hoping for, I'll certainly give it a go this week.

It's a pity that, after googling for it for the biggest chunk of an hour, I've come to realise information about it (and the supercluster) seems to be pretty scarce and dealt with nowhere but on the odd mention here on CN or scientific papers such as this "impossible-to-read-on-small-screens" paper:

https://iopscience.i...00465/fulltext/

With an 8” you can see lots in open clusters.
When I started digging into the spectra of cluster members, it becomes obvious that many of the brightest members have often evolved off the main sequence or are actually unresolved main sequence binaries (the light of two or more stars) and occasionally one will find a blue straggler candidate.

I enjoyed “discovering” 40 Cnc. Here’s an article about 40 Cnc https://www.aanda.or.../aa11495-08.pdf

Here’s a much older article that talks about several blue stragglers you could probably see.
http://articles.adsa...000069.000.html

One advantage of observing open clusters in the Gaia age is that you start to have more confidence in which stars are truly cluster members and therefore which might be blue stragglers.

Here’s a link to Gaia data on open clusters that often affords a very different image of the clusters (based on conservative membership) that often extend far beyond the typical size of the cluster.
http://vizier.u-stra...e=J/A A/616/A10

Edited by Organic Astrochemist, 25 August 2019 - 11:54 PM.

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#17 theApex

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Posted 26 August 2019 - 09:38 AM

That's plenty of great sources. So much so that an initial search for the first star mentioned in the 60s paper has yielded a few interesting scientific papers where you can clearly notice an interesting learning curve as they progressed.

#18 Keith Rivich

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Posted 26 August 2019 - 10:10 PM

I got this email from Ms Parada, lead author of this paper:

https://arxiv.org/pdf/1609.02115.pdf

 

Hi Mr. Keith,

Please find attached the list with the RA, DEC, and V (HST/ACS F606W)
magnitude for the blue stragglers in 47 Tuc studied in
https://arxiv.org/pdf/1609.02115.pdf. The blue stragglers in the list
were selected in the ultraviolet colour-magnitude diagram (top-right
panel of figure 4 of the paper).

I hope this helps,

Javiera Parada
PhD Candidate
Department of Physics and Astronomy
University of British Columbia
Vancouver, Canada.

 

She sent me this list of blue stragglers in 47 Tuc:

Attached File  47 tuc BS.txt   3.45KB   4 downloads

 

Looks like the brighter ones are in the 14th magnitude range which sould be observable in your 8" under good skies. Good luck!


Edited by Keith Rivich, 26 August 2019 - 10:11 PM.

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#19 theApex

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Posted 27 August 2019 - 02:27 PM

Fantastic! Thank you for sharing that.

It's a pity Skysafari Pro at least lacks even the magnitude 14 one.

Edited by theApex, 27 August 2019 - 02:28 PM.



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