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VYS 2 - Cas

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#1 ssmith

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Posted 27 October 2021 - 08:30 AM

Another fascinating nearby Red Dwarf system - a verified triple system and perhaps a quad.  Paper

 

 

YVS2 V547 Cas C9 9-15-21 3fr.jpg


Edited by ssmith, 27 October 2021 - 09:18 AM.

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#2 dhkaiser

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Posted 27 October 2021 - 09:10 AM

I think you missed a digit on the B star?



#3 ssmith

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Posted 27 October 2021 - 09:15 AM

yup - thanks


Edited by ssmith, 27 October 2021 - 09:19 AM.


#4 tdfwds

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Posted 27 October 2021 - 09:39 AM

Interesting paper!  I've only scan read it so I'm not sure if they did do a full correction for B with regards Aa for one orbit, or whether they just made sure the B versus Aa tallied with the B versus Aa,Ab interferometric stuff, or whatever, but I kind of notice one thing.

 

The Ab and B stars are of similar mass, and all are quite close, so going for two planar orbits solution (which seems to be the way) and using the barycenter of Aa,Ab seems kind of fair but it is kind of like thinking, but not quite, that Jupiter and the Sun have an orbit, and Saturn orbits around that orbit centre, or even Neptune.  I suppose it is to do with the mass ratios, Jupiter and Saturn are a lot lighter than the Sun, and the distances don't add up the same (although the distances for this one are a bit like for some multiple "exoplanet" systems.  Then again, the Sun - Jupiter barycentre is I think just inside the Sun's "surface" so I suppose we just ignore that the planets go around the barycentre in most illustrations and orbits.  These things have ~ 2:1 ratios for Aa compared to the other two, and ~ 1:1 for Ab:B.

 

On the other hand the loose "rule" that hierarchical systems are necessearly co-planar, especially trinaries, doesn't worry as much if you think of Ab and B both going around Aa like in the Solar System, making the three more likely co-formed from the same lump of muck.

 

Just idle thoughts.

 

Certainly, in terms of proper motion, this thing shifts!!!  Nearly half an arcminute in around 16 years!!!

 

For anyone interested in variable stars too, this is a good example of something sometimes difficult to explain, that fast proper motion stars can pretend to be hight amplitude variables following a fade over years :-

 

https://asas-sn.osu....42-5f5de8a596e1

 

it's actually that they just go of centre of the earliest aperture annulus or whatever photocentric x,y thing locked into in the pipeline, instead of just looking for the photocentre everytime (which is a guess as to what happens, because you can see it happen in a lot of surveys, not just ASAS-SN).  False positives.

 

Nice image, BTW!

 

EDIT : Here's an attempt at drawing the two orbits to scale as centred on Aa (N down E left).

 

TRUE EDIT : image removed as fatuous!  Apparently the other orbit was NOT of AaAb but of Bb!  Icarus, or the publishers who own them, are very tight fisted and don't even allow open access to their very, very old papers as far as I've ever been able to find out, and equally I've never really seen many Icarus preprints on arxiv/astroph so they likely disallow that too, so you'll have to just read the following abstract or simply fork out tens of bucks.  Strange really, Icarus is a Solar System journal usually, maybe this is in it because it is a potential exoplanet?

 

https://ui.adsabs.ha.....712A/abstract

 

Anyway, that's a bit more on the quadruple bit, although from the abstract it doesn't REALLY sound to have been formally confirmed (that is, hasn't been imaged, astrometric if anything).  I made a bit of a pig's ear of this one.


Edited by tdfwds, 28 October 2021 - 08:43 AM.

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#5 tdfwds

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Posted 27 October 2021 - 09:53 AM

With respect to Figure 2 in the paper, am I reading it wrong?  It says the arrow is in the direction of orbital motion, well, if that is the case the 1989 measure was taken in the future as it is AFTER the 2005 measure...   ...or was it taken in the past but only after 2005 had happened.

 

(Clocks change end of this month, I'll get similarly confused then except for on the automatic stuff and the stuff with a toggle button, but that's only the electronic stuff.  I can do the clocks okay, it's figuring out whether I'm going to "lose" or "gain" an hour's kip that confuses me).



#6 c2m2t

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Posted 27 October 2021 - 10:11 AM

Hi Steve!

Excellent image...you know me, what scope and exposure settings were you using??!!

 

That's an interesting report. Can you image looking through a 6m "visual" telescope??!! grin.gif That speckle interferogram just blows me away. Can anyone offer up why this system does not bear a "ES" Espin designation? The report indicates the system was first observed by Espin and Milburn in 1926.

 

Cheers, Chris.



#7 tdfwds

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Posted 27 October 2021 - 12:00 PM

Hi Steve!

Excellent image...you know me, what scope and exposure settings were you using??!!

 

That's an interesting report. Can you image looking through a 6m "visual" telescope??!! grin.gif That speckle interferogram just blows me away. Can anyone offer up why this system does not bear a "ES" Espin designation? The report indicates the system was first observed by Espin and Milburn in 1926.

 

Cheers, Chris.

Well, I've checked the paper at the ADSABS record and it's not an Espin, it's a Milburn, and it is actually Milburn 377.

 

But, when I search on the WDS I can get up to MLB 376 and I can get MLB 380 onwards, but MLB 377, 378 and 379 are not on WDS, despite being in the paper.

 

The position's okay, the PA and Sep and mags are okay, the new objects listed in the same table after 380 inclusive are in the WDS (well, one or two missing).

 

In other words, the question hasn't been answered, it's just been moved.

 

http://articles.adsa...000135.000.html

 

solved, see below


Edited by tdfwds, 27 October 2021 - 12:22 PM.

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#8 c2m2t

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Posted 27 October 2021 - 12:17 PM

Hi tdfwds!

Thanks for that insight and data check. Next time I communicate with Brian Mason on something a bit more pressing, I'll ask the question. Maybe he will have some insight on this.

 

Cheers, Chris.



#9 tdfwds

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Posted 27 October 2021 - 12:32 PM

Hi tdfwds!

Thanks for that insight and data check. Next time I communicate with Brian Mason on something a bit more pressing, I'll ask the question. Maybe he will have some insight on this.

 

Cheers, Chris.

Hi again, actually, it's solved.

 

I was just doing an update on my post when one of the data searches I was doing found some heavily javascript riddled page which crashed the browser, as can happen.

 

Anyway, what I was saying was, I looked up VYS of VYS 2 and the first WDS reference for him is 1927, and I doubted I'd find that scanned anywhere as observatory pubilcations barely existed, short runs probably not much outside the McCormick Observatory involved, and if that doesn't exist anymore, the originals could even have gone, but they may be archived and copies may exist at Lowell, RAS Library or USNO.  I did a search anyway, and found that the guy, Vyssotsky, had dropped a note the same year into the original "Popular Astronomy" as the object was so ridiculously fast in proper motion (actually, I wonder if SSMITH's referenced paper fixed for proper motion or not in case that explains the wiggle by moderating the orbit at certain points along it?).

 

https://ui.adsabs.ha.....213V/abstract

 

It could be a list of abstracts quoted from other main papers, you still get that in some general journals and newsletters.

 

There you have it.  After finding the Vyssotsky pubilcation was 1927 I guessed that maybe the WDS, or more likely the IDS or even ADS before it (later versions postdate 1927 just) based things on when first measured, not when first in print, so he had priority.  That'd explain it good enough.

 

And the A&A paper wouldn't be aware of WDS reference files at a guess, or maybe just followed the route for the Gliesse ID via simbad to online references.  That's the way it often happens with older obscure stuff, especially double stars.  If Milburn hadn't independently discovered it they may well not have found any reference!


Edited by tdfwds, 27 October 2021 - 12:34 PM.

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#10 ssmith

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Posted 27 October 2021 - 04:22 PM

Hi Steve!

Excellent image...you know me, what scope and exposure settings were you using??!!.

 

Hi Chris - Scope C9.25 @ f6.3 - Olympus M10 Mkii - ISO1600 - 4 sec exposure.

 

The name Vyssotsky sounded somewhat familiar to me - I figured out that a few years back I photographed a planetary nebula that he discovered - also in Cassiopeia.

 

ARO90 PN Cass C9 12-26-19 3fr small.jpg


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#11 flt158

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Posted 27 October 2021 - 04:50 PM

Spectacular images, Steve, as always. 

 

Now when am I going to get some clear skies? fingertap.gif

 

Aubrey. 


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#12 ssmith

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Posted 28 October 2021 - 08:48 AM

,For anyone interested in variable stars too, this is a good example of something sometimes difficult to explain, that fast proper motion stars can pretend to be hight amplitude variables following a fade over years :-

 

https://asas-sn.osu....42-5f5de8a596e1

 

it's actually that they just go of centre of the earliest aperture annulus or whatever photocentric x,y thing locked into in the pipeline, instead of just looking for the photocentre everytime (which is a guess as to what happens, because you can see it happen in a lot of surveys, not just ASAS-SN).  False positives.

tdfwds - could you please expand or clarify the above remarks regarding the pseudo variability via proper motion - I can’t quite follow the argument.

 

thanks !


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#13 tdfwds

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Posted 28 October 2021 - 09:59 AM

As VanJan said, you need to succeed.  Definition of something that succeeds : - a beakless budgie [ancient joke]

 

Now, after making a mess of the orbits, I need to fix 'em, big orbit is VYS 2AB, little orbit centred on A is MYC 1AaAb, littler orbit centred on 2022 position of B (ish) is VYS 2B.

 

This should now be right.  Orbital periods for AaAb and B (which I suppose should technically be either BaBb if brown dwarf or Bb is exoplanet, if in any way real at all) are both around 15 or so years, so both orbit 14 to 15 times for every orbit/revolution of AB.

 

This is all dependent on me having got it right this time!

 

 



#14 tdfwds

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Posted 28 October 2021 - 10:22 AM

tdfwds - could you please expand or clarify the above remarks regarding the pseudo variability via proper motion - I can’t quite follow the argument.

 

thanks !

Okay then, and remember this is all guesswork on why, but yes it does happen, and I'm not the only one who has ever mentioned it, I've seen it mentioned on AAVSO forums in the past by VSX team, though I'd not be able to find you a link for such, so that's anecdotal, not firm, evidence...  Neither am I a observing photometrist or CCD user.

 

Anyway, let us assume that wide field photometric surveys, which incidentally often have resolution as poor as several to many arcseconds per pixel in their images, have to anchor astrometrically.  Possibly they use an astrometric catalogue for seed, after all, they have to identify the object's position on the sky to some level of accuracy, which is often far better than the images are capable of, and they often have cross identification with known objects too, possibly connected to this.

 

Now, if they use an annulus for the photometry centred on a fixed point, of so many pixels radius, then a high proper motion object studied over time would slowly drift from this centre, and part of the image, and thus some of the incident photons, would start falling outside the annulus' aperture radius in which the photon count is made.  And as the thing steadily moved out of the J2000 (for instance) position due to no proper motion corrections being made on the position then less and less of the image appears in the annulus, and you end up with an apparent "monotonic" fade over time.

 

I first saw it years ago looking for variable objects of many kinds in OGLE data, and didn't at first understand it as it didn't really tally with any form of lightcurve save possibly a very late stage nova or supernova lightcurve decline, but those made no sense as everyone would have noticed (super)novae that bright as their maxima would have consequently been at much higher magnitudes.  On checking a star or two I noted some were large proper motion objects (less data around for such things in those days but data were there for high motion stars).  I thought that must be the reason, and I have since seen it noted once or twice over the long time since by others.  Having a vague idea how aperture photometry is done, and having also noted earlier that very low amplitude 'shadow' or 'ghost' twin variables can appear even several pixels distant from the true variable due to the effect that latter has on the background field of the former I guessed at the above.

 

But whatever the true cause, and/or the proper way of describing it, it happens, even if my assumption of why is bunkum.

 

There is no physical or astrophysical reason for any red dwarf likely Halo star, single or multiple if the companions are less massive, to show such steady fading as in the above lightcurve, and eclipses of A via a very slow can be readily dismissed as none of the orbits have an inclination of greater than 80 degrees, and even if A had another invisible companion as we no the distance and the scale of the system already and from the above lightcurve full amplitude we can tell that such a putative fifth star would have to be nearly as big as and quite close to Aa, and therefore of short period, and that lightcurve is not characteristic of an EW eclipser of any kind.  Exotic possibilities could be made I suppose, like extrapolation from epsilon Aurigae (which is a totally different kind of star and setup anyway), but the easier answer is that it is an artefact of the photometry.  You could add to this the numerous and various catalogues that report similar bright magnitudes for the system over many years, right upt to gaia in 2016 EDR3, with no hints of such a large fade.

 

Hope that helps, that's the best I can manage in my own way of trying to describe what I think I mean ; )

 

EDIT : Indeed the epoch of your own image probably coincides with an epoch on the ASAS-SN lightcurve!  ASAS-SN will be showing the combined magnitude for AB, it will not be able to resolve it, although with the large magnitude difference the combined magnitude for AB and the magnitude for just A won't differ by more than a few tenths at most anyway.


Edited by tdfwds, 28 October 2021 - 10:25 AM.


#15 ssmith

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Posted 28 October 2021 - 01:30 PM

tdfwds -

 

Thanks so much for the clarification - that explains things nicely.  For a real world example of what you were saying I went to plate solve my photo of V547 Cas in ASTROMETRICA and as you explained, due to the high proper motion of the star it is beginning to fall outside the photometric aperture as shown below:

 

V547 Cas Aperture.jpg

 

Also thanks for pointing us to the ASASSN database - this is a resource that I wasn't familiar with but I have already made some use of it in regards to some of my other ongoing projects.


Edited by ssmith, 28 October 2021 - 01:43 PM.

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#16 tdfwds

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Posted 28 October 2021 - 05:04 PM

ssmith : You're welcome, actually it was a close run thing, a few minutes after posting that the 'net died on me, and stayed dead for about 5 hours.  Doing some checking it looks likely I wasn't alone, as it seems to have been a regional infrastructure glitch, not just my ISP, though I'll never find out for sure (probably some exchange issue somewhere).  It was lucky though, as when I lose a blurb when it is nearly finished subsequent replacements always seem weaker than the original!  And shorter, coz I lose the enthusiasm.

 

Anyway, thanks to you too for the image!  I feel a lot more confident in my assumptions now, although I'm convinced they're too simplistic to be the whole story, or for that matter an accurate one.

 

Now, Astrometrica, I think years ago it started having an option to download astrometric reference for a field via internet, from VizieR, the means having been passed around a bit after I managed to pass on the core "http get" to projectpluto after finally figuring the thing out by simple trial and error (not being web savvy).  I think there may have been a coincidental discovery of this by several people though, I know it soon caught on, and only really became relevant with certain new bulk catalogues.  Now websites will often give you a breakdown of the API core, although something called JSON is taken over which means you have to know how to code in xml or something, which is a pain.

 

Anyway, the thing is I have never used astrometrica, but the catalogues it used to use were J2000.  Although there were some astrometric catalogues that could have been used, like UCAC incarnations, none of the quality ones were full sky.  Furthermore, the highest proper motion objects weren't even included in those, as cross linking "faint" stars in the old catalogues needed all catalogues ot have common matchable positions, probably the Astrographic Catalogue for UCAC2 (properly AC2000, which was epoch of relevant plate but equinox of J2000, as epoch and equinox are not the same thing, I believe after a rescanning of original plates at USNO, not sure, the memory, it leaks, and I can't always be bothered to re-read entire papers not looked at for years).  In other words, even though there were resources, possibly even in the catalogues being used, I am not sure how many astrometric reduction software programs availed themselves of this.  After all probably over 99% of the stars in the big catalogues didn't need it as the proper motion made negligible in the early 2000s.

 

Now, I've heard of these now using GAIA data, but the thing most folk don't realise is GAIA is published to an epoch, DR2 was 2015.5, EDR3 is 2016.0, and those are 'mean' representative epochs for the whole catalogue.  The source GAIA data, if accessed via primary TAP sources for instance, or even files downloaded (it's broken up into lots of little bits I believe), is only in that epoch.  When VizieR imports it for use they ADD J2000 RA and Dec columns not there in the visible.

 

It would be wiser for the astrometric reduction software to use the 2016 columns.  I don't think it is a coincidence that on the VizieR Xmatch service (there's a link at the opt of any VizieR page) the catalogue selections include many large catalogues for crossmatching, but one added relatively recently, even after EDR3 first appeared there, is a "GAIA 2016" option.  I'd guess that's likely due to feedback from professionals as they didn't do a GAIA 2015.5 for DR2 option.

 

If you want to crossmatch small lists against GAIA then the small lists will likely be to epoch and equinox J2000, but if you are doing images, you want as near an epoch to the date of your image as possible if there is a high proper motion object involved.  In other words, if current astrometric reduction software is NOT using 2016 epoch GAIA coords it OUGHT TO BE, or at least have an option to select that over the J2000 ones VizieR provides (it also provides the source 2016 ones, as I said, the J2000 column is an ADDED one).

 

None of this is really clever or techy or anything, it's just convention and people being aware of the conventions.  Like we all have to learn the vagaries of discovery designations, either oldstyle or new style, for doubles, and same for variables, "there can't be that many, last known bayer code is P for P Cygni, let's use an R per constellation..., what, another?  Okay, S, T...Z.  More?  RR RS...RZ.  Not again!?  SS, ST...SZ.  ZZ!  More!  Okay, well start at the beginning, AA (A will exist), etc, until we get to PZ.  Oooh, look lots of stars and lost of variables in Sagittarius, darn it, how many do the rest add up to?  Alright, V335 then.  That'll be okay until we get to infinity!

 

Stuff like that, the quaint stuff we all get used to in astronomy that defies logic a lot of the time, it's just historical happenstance, or good reason, but below it is a convention, and epoch as well as equinox J2000 has got as rigid a convention as B1950 did, but it is now 2021 and counting!  Finally, isn't really equinox J2000 and epoch whichever the latest data release uses, it's some sort of barycentric thing and what have you, but he differences are negligible as far as most people are concerned, as they are quite below normal Earthside skies resolution.

 

And if you think that lots bad, there's some new scheme nowadays, beginning with 'h' and has the sky cut up into trianlges or such, and it's compressible or something, and decodes to a position via algorithms, which is beyond me.  HEALpix?

 

Anyway, here's the http get for various variable start resources, beware any wordwrap

 

https://asas-sn.osu....sort_by=raj2000

 

change ra and dec accordingly. in decimal degrees, I think radius is in arcmins for this one.  Scroll to bottom to find link to click on to get lightcurve.

 

http://nunuku.caltec...short&PLOT=plot

 

again, ra and dec in degrees, radius in arcmins. %20 is html ish for a space, in hex (in other words ascii hexadecimal 20 is the space character, = decimal 32).  This bit of sky not included in cover.

 

https://irsa.ipac.ca...0015&FORMAT=CSV

 

that'll give you a ZTF .csv file to download, if data available, positions in decimal degrees, radius looks also to be in degrees (guessing, I can't remember them all, they all choose different methods!).

 

https://mast.stsci.e... 67.234 r=1m"}

 

that's tess, %22 is comma, and there's others, it won't work with the actual characters for some reason, again decimal degrees, but minimum radius has to be one arcminute as here.  You have to scroll the table far right to make sure you have nearly 0 arcsec offset for the position to make sure it is the right star.  Click on the lightcurve symbols and a lightcurve will likely pop up, especially for TESS "QLP"  (quick look p_something).  Using the pcdsap or similar (spelling!) instead of straight sap tickbox (use the orange, not the blue lightcurve) and best to go full zoom.  At times the lightcurve won't pop up.  Then click the floppy disk symbol next to the lightcurve one and you will download a file, find the .llc file in that, and plot time against SAP for this one.  It's a FITS file, but a fiTs file, as in table, not fIts as in image (flexible image and table system, but now usually called flexible image transport system I believe so folk forget it is for all data, not just images).  Brightness is electron counts per second, so you'll have to figure that out yourself.  The SPOC stuff rarely gives a lightcurve or downloads, often given a 'needs curl' error.  Even if you get it to work you'll find it is an immense file, likely as mostly fairly raw data.

 

Finally, this will get you an (overexposed here) set of panstarr images for quicklooks

 

http://ps1images.sts...output_size=512

 

usual think, this time it's 'size' not 'radius' and an arcsecs box (I wish they'd all be consistent!)

 

and SDSS explore http://skyserver.sds...3&dec= 67.23433 which won't work for these stars (all these coords are for gaia edr3 position of VYS 2A) but is again decimal degrees, no size option, and would be overexposed for most doubles anyway.

 

If your skycharter allows http(s) linkouts, like mine does, it makes checking stuff VERY quick.

 

Cheers

 

/endwittering

 

BONUS : SIMBAD but you have to use %2B instead of plus, but you can still use - for southern declinations

 

http://simbad.u-stra...ius.unit=arcmin




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