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LPV Webinar - Miras from an Astrophysical Standpoint

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croberrw
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LPV Webinar - Miras from an Astrophysical Standpoint

LPV'ers, 

Stan Walker of Variable Stars South has agreed to present on a topic he was originally going to give at VSS-6 via Zoom. 

We're going to present on Saturday June 6th at 2200 UTC. (6pm for those of us on the US east coat and early Sunday morning for Variable Star South members) 

The meeting link is here: 

Join Zoom Meeting

https://zoom.us/j/6610631137

Meeting ID: 661 063 1137

 

I really appreciate Stan agreeing to do this. Hopefully people like this and we can schedule other observers/researchers willing to talk about thier work. 

As we're teleconferencing more and more, the opportunities to collaborate and share our knowledge with people around the world is truly exciting. 

Clear Skies!

Rich Roberts (RRIA)

croberrw
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Outline

Here is the outline for the talk. We plan to take a few minutes for questions in between each section. Each section is 2-3 slides

1.Introduction to pulsating variable stars

2.Double  Maxima  Miras  

3.Filters  

4.Radial velocity measures 

5.BH Crucis  

6.R Centauri  

7.Observing the target stars 

8. Summary & Conclusions

croberrw
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Abstract for Presentation

One hundred and fifty years of intensive time series photometry  (TSP) of long period variables such as Mira stars have found less than a dozen stars with true long term changes – thus interest seems to be falling.   But amateurs now have access to equipment capable of measuring other aspects of these stars:  filters and detectors which allow UBRVI colour photometry, with extensions to JH and K passbands;  spectroscopic equipment capable of measuring  radial velocities accurately;  all of which can be combined with satellite measures of distance and other things.

 

This project is largely based upon the known attributes of two Mira stars which have shown two maxima per cycle.  There are similar stars where detailed study of the astrophysical aspects would be valuable.  When successful results are obtained these can be used as a template for observing the full range of long period cool stars – Miras, SR stars and similar objects.  This provides a raison d’ệtre for amateur measures of these stars for the next century, even though the increasing number of surveys may relegate TSP to  a role comprising data-mining of these surveys.

Mark Blackford
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LPV Webinar

Hi Rich and Stan,

It was disappointing that Stans's talk, and the entire Variable Stars South Symposium, had to be cancelled due to the Covid-19 travel restrictions. So I was pleased to hear that this LPV Webinar was being planned. I'm really looking forward to it. Cheers,

Mark

croberrw
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Stan's Backgroud

Here is some background on Stan for those who don't know him. He has a ton of experience and his talk should be beneficial to all of us. 

Like many other Southern Hemisphere amateurs I began serious observing by joining the RASNZ Variable Star Section in the mid-1960s and made visual measures of Miras and Dwarf Novae - about 10,000 over a decade or so.  Things were much different in those days with few charts, not all with sequences.  Many measures had to use lettered sequences. I became more heavily involved in astronomy when the Auckland Observatory opened in 1967 with a 50cm Zeiss telescope and a Board of Trustees which didn't know what to do with it.  Nor did I, but a group of us got together, were impressed by Brad Wood's book 'Photoelectric Photometry for Amateurs' and the show was on the road.  I'm a chartered accountant by profession but I've met with, worked with and talked with many of the leading photometrists in the southern hemisphere. 

 

We extended the LPV observing to UBV measures which provided a little more accuracy, but mainly allowed us to determine colours, B-V relating to temperature, U-B allowing the measures of emission from the extensive gas shells surrounding these stars.  In 1970 I was admitted as a member of the International Astronomical Union on the 'Variable Stars' commission (now changed to 'Pulsating Variables')  and in 1976, largely due to work in the CV field and the setting up of a very effective photoelectric system in Auckland, I was invited to join the 'Close Binary' and 'Photometry and Polarimetry'commissions.

 

Along with the late Brian Marino I was research coordinator at Auckland Observatory from 1968 to 1990 when I retired to New Zealand's Far North district.  We published many papers in the Royal Astronomical Society of New Zealand's journal, Southern Stars, on CVs and pulsating variables and a dozen or two in refereed international journals.  These included JAAVSO papers on R Centauri and BH Crucis.  Some of this work was described in two papers presented at the AAVSO centennial in 2011.

 

I have always been interested in the astrophysical aspects of stars and more recently have largely given up direct measures in favour of analysing measures by other observers, one of the most prolific being Giorgio di Scala in New South Wales.  In analysing measures from the International Database I have noticed that whilst this is often quoted by professionals who use the visual records to provide a historical skeleton on which to support more complex measures using a variety of detectors, the use of filtered measures other than with the V filter is almost non-existent.

 

Many of our members now measure stars using UBVRI, JH and perhaps K filter systems.  In some ways we are at a crossroads similar to the early days of photo-electric photometry in the 1950-70 period.  CCD, CMOS and other detectors make observing much easier and have the potential for greater accuracy and a range of filteredwavelengths - almost like the change from black and white to colour TV.  Will astronomers of the twenty-second century look back on our effort with the same respect that we do with the early pioneers of high quality visual observing in the 1880s?  We must make this happen!

 

The presentation today explores some ideas in a small area of pulsating stars, Miras with two maxima per cycle, viewed against the much wider background of all longer period pulsating variable stars.

 

 

croberrw
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Reminder

We're going live tomorrow! Hope to see everyone there. 

Who plans on attending? 

Clear Skies, 

Rich Roberts (RRIA)

weo
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Looking forward to Stan's presentation

I'm really looking forward to Stan's presentation tomorrow and to hearing more about Miras. Thanks for making this virtual event possible!

Elizabeth

Mark Blackford
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Reminder

Hi Rich,

I'll be there too, looking forward to Stan's presentation. Cheers,

Mark

Sebastian Otero
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Be "there"

I am looking forward Stan's presentation too.
The other day Bert called my attention to a red variable and it turned out to be a 605 d-double maxima mira so I thought about Stan ;)

Cheers,
Sebastian

croberrw
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Very Cool Sebastian. What is

Very Cool Sebastian. What is the name of the red variable? I'd like to look it up. 

Clear Skies, 

Rich 

Sebastian Otero
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LMC V2847

Hello Rich,
It is a LMC variable so you have to be in the Southern hemisphere to observe it. Stan will be happy ;)

VSX data:

LMC V2847

croberrw
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You Southern Hemisphere guys

You Southern Hemisphere guys get all the good stuff! 

croberrw
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T - 15 min

T - 15 min

croberrw
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Slide Deck

I converted Stan's slide deck to pdf and attached it for those interested. 

The talk and subsequent discussion was very interesting. 

I'm glad the webinar was so well attended and that fact that observers from around the globe joined in. 

Clear Skies, 

Rich Roberts (RRIA)

sfy
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Great webinar

Stan's webinar was excellent - really interesting material and much food for thought. Even though it was getting on for 1 AM here in the UK, I was fully engaged!

Thanks for uploading Stan's pack, Rich.

David Benn
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Agreed, great webinar

Agreed. I really enjoyed Stan's webinar today. Thanks Stan and Richard for organising this.

I'm often up late, so getting me out of bed at 7:30am on a Sunday is not easy!

It was also great to hear input from a variety of people I've only communicated with via forums and email.

I had great fun reproducing the results Stan presented by applying Weighted Wavelet Z transform, plotting B-V etc in VStar during the talk. I plan to add some of the variables Stan talked about to my observing list.

I've been meaning to watch the last webinar (in which Sebastian was a presenter, among others as I recall), so I'll have to go do this now.

I use tools like Zoom and webex for work every day, and I think these tools are awesome for organisations like AAVSO and VSS.

David

PYG
PYG's picture
Stans webinar

Really enjoyed Stan's webinar last night/this morning.   Many thanks for that Stan.

As a CV observer I only observe three MIra stars, but I'll be adding KL Cyg to my list following Stans talk.

Gary

sfy
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Recording

I think someone said Stan's talk was being recorded. Is there a link please?

Jeremy

croberrw
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It was recorded. Apparently

It was recorded. Apparently the file is too large to upload directly to youtube. When I figure out how to best manipulate the file to meet their requirements, I will post a link to it in this thread. 

Clear Skies, 

Rich Roberts (RRIA)

sfy
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OK, many thanks Rich. Jeremy

OK, many thanks Rich.

Jeremy

croberrw
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you tube link

https://www.youtube.com/watch?v=6f3V8MA__oQ

Here is the link to the recording for those who could not attend. 

Mark Blackford
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Presentation by Stan

Hi All,

I really enjoyed Stan's presentation on Sunday morning (my time) and I am glad the PDF and video have been made available so I can look back over some sections again. The video quality is excellent.

Thanks for organising this webinar Rich, and I hope to see more in the future from all observing sections. Cheers,

Mark

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