The difference between binary and non-binary

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John Donne United States of America
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The difference between binary and non-binary

#1

Post by John Donne »


In my study of star doubles the terms binary and non-binary are used.
Non-binary seems to mean that they are only double in appearance but not by gravitational relationship.
Are non-binary doubles actually not considered real double stars?
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Re: The difference between binary and non-binary

#2

Post by Ruud »


Doubles aren't triples and triples aren't binaries. But any star that's not single is a multiple. That at least must be true.
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Re: The difference between binary and non-binary

#3

Post by kt4hx »


It is correct that a binary star is a true gravitationally bound pair that orbit their common barycenter. The term non-binary, or frequently called an "optical double", are close pairs that are only such based on chance alignment by line of sight. For scientific purposes, the latter are not considered double stars and are of no real value to the scientific community. However, many optical doubles are quite attractive visually and are certainly worthy of observation.

As an aside the original printing of the Cambridge Double Star Atlas included both kinds, while the second edition scrubbed the optical doubles and added many more true doubles. I personally have an issue with that mindset because the CDSA is an amateur publication that is of little interest to professionals. While some amateurs may be involved in assisting the professional community with the science aspect of double stars, most are not. So removing the optical pairs is a disservice to the amateur community in my view. The way I see it, why remove old friends to introduce new ones? If one already has the first edition, I would recommend keeping it while acquiring the second, as they compliment one another.
Alan

Scopes: Astro Sky 17.5 f/4.5 Dob || Apertura AD12 f/5 Dob || Zhumell Z10 f/4.9 Dob ||
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Re: The difference between binary and non-binary

#4

Post by John Donne »


Thank you very much , Alan.
I enjoy observing doubles. I believe I have observed both kinds. But I think many that I view are the non-binary type. I will dig deeper into this now as I observe.
Thank you again.
SCOPES :ES127 f7.5, SW100 f9 Evostar, ES80 F6, LXD75 8" f10 SCT, 2120 10" f10 SCT, ES152 f6.5.
MOUNTS: SW AZ/EQ5, MEADE LXD75, CELESTRON CG4, Farpoint Parallelogram.
BINOCULARS: CL 10X30, Pentax 8X43, 25X100 Oberwerks.
EP: Many.

"I am more than a sum of molecules.
I am more than a sum of memories or events.
I do not one day suddenly cease to be.
I am, before memory.
I am, before event.
I am"
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Re: The difference between binary and non-binary

#5

Post by kt4hx »


John Donne wrote: Thu Feb 25, 2021 10:07 pm Thank you very much , Alan.
I enjoy observing doubles. I believe I have observed both kinds. But I think many that I view are the non-binary type. I will dig deeper into this now as I observe.
Thank you again.
My pleasure John. While I am not much of a double star chaser, I have observed a few on purpose. I see a great number during my galaxy hunts, but I don't log them. One of the most beloved double stars, Albireo in Cygnus, is a bit of a quandary. Depending upon the source you read, the two main stars may be physically associated or they may not be. A great deal of what I read seems to indicate they are not physically related, have differing radial velocities and are about 60 LY apart. However, Albireo A is itself a true multiple system. Regardless, they are indeed beautiful, and for me, that is all my eyes and mind are concerned with. :)
Alan

Scopes: Astro Sky 17.5 f/4.5 Dob || Apertura AD12 f/5 Dob || Zhumell Z10 f/4.9 Dob ||
ES AR127 f/6.5 || ES ED80 f/6 || Apertura 6" f/5 Newtonian
Mounts: ES Twilight-II and Twilight-I
EPs: AT 82° 28mm UWA || TV Ethos 100° 21mm and 13mm || Vixen LVW 65° 22mm ||
ES 82° 18mm || Pentax XW 70° 10mm, 7mm and 5mm || barlows
Filters (2 inch): DGM NPB || Orion Ultra Block, O-III and Sky Glow || Baader HaB
Primary Field Atlases: Uranometria All-Sky Edition and Interstellarum Deep Sky Atlas
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"Astronomers, we look into the past to see our future." (me)
"Seeing is in some respect an art, which must be learnt." (William Herschel)
"What we know is a drop, what we don't know is an ocean." (Sir Isaac Newton)
"No good deed goes unpunished." (various)
Some people without brains do an awful lot of talking, don't you think?” (Scarecrow, The Wonderful Wizard of Oz)
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Re: The difference between binary and non-binary

#6

Post by Bigzmey »


For the purpose of observing optical doubles (or multiples) are still considered doubles (or multiples), even though they may not be gravitationally connected.

There are a few reasons for that. Many of optical doubles are nice looking colorful pairs and you will be me missing their beauty if to focus only on proven binaries. There are also many of unresolved nature, where the binary status is not proven but not disproven either. Finally, many optical doubles were first cataloged by famous observers of the past. It is fun and rewarding activity to follow in their steps. For example I am working on completing STF catalog, and you can't do it without observing optical doubles.

Washington Double Stars (WDS) catalog maintained by the United States Naval Observatory is the most complete and trusted database for multiple stars and it lists optical doubles together with proven binaries and systems of unknown nature.
Scopes: Stellarvue: SV102ED; Celestron: 9.25" EdgeHD, 8" SCT, 150ST, Onyx 80ED; iOptron: Hankmeister 6" Mak; SW: 7" Mak; Meade: 80ST.
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Diagonals: Baader: BBHS mirror, Zeiss Spec T2 prism, Clicklock dielectric; TeleVue: Evebrite dielectric; AltairAstro: 2" prism.
Filters: Lumicon: DeepSky, UHC, OIII, H-beta; Baader: Moon & SkyGlow, Contrast Booster, UHC-S, 6-color set; Astronomik: UHC.

Observing: DSOs: 3106 (Completed: Messier, Herschel 1, 2, 3. In progress: H2,500: 2180, S110: 77). Doubles: 2382, Comets: 34, Asteroids: 255
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Re: The difference between binary and non-binary

#7

Post by Bigzmey »


Here is a great search engine which uses WDS database

https://www.stelledoppie.it/index2.php?iddoppia=81449

You type in the star of interest and it will show all the components listed for this system and their physical nature. I did Albireo as an example. The famous AB pair is listed as not physical, but there are other 13 components recognized for this system, some proven binaries and some of unknow nature.

You can also filter and create observing listed by constellation, separation, magnitude. A great resource for any double splitter.
Scopes: Stellarvue: SV102ED; Celestron: 9.25" EdgeHD, 8" SCT, 150ST, Onyx 80ED; iOptron: Hankmeister 6" Mak; SW: 7" Mak; Meade: 80ST.
Mounts: SW: SkyTee2, AzGTi; iOptron: AZMP; ES: Twilight I; Bresser: EXOS2; UA: MicroStar.
Binos: APM: 100-90 APO; Canon: IS 15x50; Orion: Binoviewer, LG II 15x70, WV 10x50, Nikon: AE 16x50, 10x50, 8x40.
EPs: Pentax: XWs & XFs; TeleVue: Delites, Panoptic & Plossls; ES: 68, 62; Vixen: SLVs; Baader: BCOs, Aspherics, Mark IV.
Diagonals: Baader: BBHS mirror, Zeiss Spec T2 prism, Clicklock dielectric; TeleVue: Evebrite dielectric; AltairAstro: 2" prism.
Filters: Lumicon: DeepSky, UHC, OIII, H-beta; Baader: Moon & SkyGlow, Contrast Booster, UHC-S, 6-color set; Astronomik: UHC.

Observing: DSOs: 3106 (Completed: Messier, Herschel 1, 2, 3. In progress: H2,500: 2180, S110: 77). Doubles: 2382, Comets: 34, Asteroids: 255
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Re: The difference between binary and non-binary

#8

Post by notFritzArgelander »


kt4hx wrote: Thu Feb 25, 2021 9:44 pm It is correct that a binary star is a true gravitationally bound pair that orbit their common barycenter. The term non-binary, or frequently called an "optical double" are close pairs that are only such based on chance alignment by line of sight. For scientific purposes, the latter are not considered double stars and are of no real value to the scientific community. However, many optical doubles are quite attractive visually and are certainly worthy of observation.

As an aside the original printing of the Cambridge Double Star Atlas included both kinds, while the second edition scrubbed the optical doubles and added many more true doubles. I personally have an issue with that mindset because the CDSA is an amateur publication that is of little interest to professionals. While some amateurs may be involved in assisting the professional community with the science aspect of double stars, most are not. So removing the optical pairs is a disservice to the amateur community in my view. The way I see it, why remove old friends to introduce new ones? If one already has the first edition, I would recommend keeping it while acquiring the second, as they compliment one another.
I agree. Many purely optical doubles give a very fine view.
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
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Re: The difference between binary and non-binary

#9

Post by Piet Le Roux »


This book explains the the difference between binary and non-binary doubles and gives you a lot of information .....
https://www.pdfdrive.com/double-multipl ... 51662.html
Main Equipment : Tele Vue 27mm Panoptic, 7&13mm Nagler, Big Barlow : 8" Meade LX90ACF with Meade 2.0" Enhanced Diagonal : Camera Fuji XT100
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Re: The difference between binary and non-binary

#10

Post by John Donne »


Thank you , Piet le Roux.
This looks very good.
SCOPES :ES127 f7.5, SW100 f9 Evostar, ES80 F6, LXD75 8" f10 SCT, 2120 10" f10 SCT, ES152 f6.5.
MOUNTS: SW AZ/EQ5, MEADE LXD75, CELESTRON CG4, Farpoint Parallelogram.
BINOCULARS: CL 10X30, Pentax 8X43, 25X100 Oberwerks.
EP: Many.

"I am more than a sum of molecules.
I am more than a sum of memories or events.
I do not one day suddenly cease to be.
I am, before memory.
I am, before event.
I am"
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Re: The difference between binary and non-binary

#11

Post by Greenman »


John Donne wrote: Fri Feb 26, 2021 5:12 am Thank you , Piet le Roux.
This looks very good.
Agreed, thanks Piet.
Cheers,

Tony.

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Re: The difference between binary and non-binary

#12

Post by mikemarotta »


Piet Le Roux wrote: Fri Feb 26, 2021 4:50 am This book explains the the difference between binary and non-binary doubles and gives you a lot of information .....
https://www.pdfdrive.com/double-multipl ... 51662.html
Just to say, I am not clear that this book is available for a free PDF, even though it is provided as such. Some sites, such as Google Books and Gutenberg are careful about intellectual property. Others just take anything they can get their hands on. If the book looks like something you actually want, the way to get it is to buy it. Barnes and Noble sells it as a book currently in print from Springer.
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Michael E. Marotta
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Re: The difference between binary and non-binary

#13

Post by mikemarotta »


Bigzmey wrote: Thu Feb 25, 2021 10:55 pm...Finally, many optical doubles were first cataloged by famous observers of the past. It is fun and rewarding activity to follow in their steps. For example I am working on completing STF catalog, and you can't do it without observing optical doubles. ...
Right. Just to add icing to the cake:
In Parallax, Alan Hirshfeld explains that in the 200 years between Galileo and William Herschel, it was commonly assumed by astronomers that the stars were randomly distributed in the universe. They sought doubles, one bright, the other dim, on the assumption that the brighter one was much closer and could be a candidate for parallax measurement. William Herschel built huge telescopes and catalogued the doubles and in 1802 came to the conclusion that many are gravitationally locked and not accidentally aligned from our perspective.

For myself, the archtype is Albireo because it is an easy target and can be used at outreach events.
---------------------------------------
Michael E. Marotta
Astro-Tech 115 mm APO Refractor Explore Scientific 102 mm f/6.47 Refractor Explore Scientific 102 mm f/9.8 Refractor Bresser 8-inch Newtonian Reflector Plössls from 40 to 6 mm Nagler Series-1 7mm. nonMeade 14 mm. Mounts: Celestron AVX, Explore Twilight I Alt-Az, Explore EXOS German Equatorial
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Re: The difference between binary and non-binary

#14

Post by Baurice »


Then, of course, there are double stars that do not orbit a common centre of gravity but are physically associated. For example, it is believed that Alcor and Mizar are not a true binary but both part of the Ursa Major Moving Group.

I don't think there's a term for that.

I have photographed some over the years.
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Re: The difference between binary and non-binary

#15

Post by mikemarotta »


I am currently reading Discovery and Classification in Astronomy: Controversy and Consensus by Steven J. Dick (Cambridge, 2013).
Binary vs Double 3.jpeg
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Michael E. Marotta
Astro-Tech 115 mm APO Refractor Explore Scientific 102 mm f/6.47 Refractor Explore Scientific 102 mm f/9.8 Refractor Bresser 8-inch Newtonian Reflector Plössls from 40 to 6 mm Nagler Series-1 7mm. nonMeade 14 mm. Mounts: Celestron AVX, Explore Twilight I Alt-Az, Explore EXOS German Equatorial
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