The mass that ends up outside the orbit of the star is effectively a shell, and it therefore exerts no net gravitational force on any objects inside it. So there is an effective loss of mass, with the consequence that the runaway star ends up converting its elliptical orbit to a hyperbolic one (meaning it's traveling very nearly in a straight line once it's far from its sibling binary).jpicciri wrote:I've read many explanations for runaway stars that involve a supernova that then "releases" its companion star.
Doesn't the companion still revolve around the center of mass? Does the runaway happen after the supernova
remnants pass the orbit of the companion star? I'm not understanding the kinematics.
APOD: Zeta Oph: Runaway Star (2017 Apr 08)
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Re: APOD: Zeta Oph: Runaway Star (2017 Apr 08)
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Re: APOD: Zeta Oph: Runaway Star (2017 Apr 08)
Well, I'm sticking my neck out and offering an answer, even though I'm not sure of it.jpicciri wrote:I've read many explanations for runaway stars that involve a supernova that then "releases" its companion star.
Doesn't the companion still revolve around the center of mass? Does the runaway happen after the supernova
remnants pass the orbit of the companion star? I'm not understanding the kinematics.
Thanks,
John-
When a star goes supernova, it is blowing away much of its mass. If it has a companion, the two stars were orbiting the common center of mass at a speed that would keep both of them in orbit. But now that one star suddenly loses a lot of mass, the speed of its companion may be too high for it to stay in orbit. It may then escape in the tangential direction.
Can't the neutron star or the black hole, the compact remnant of the star that went supernova, get a kick that sends it flying away, too? I would think that this might happen.
Bear in mind that a supernova typ Ia will not leave a compact remnant behind, except in, possibly, a few extremely rare cases. I read about something like that some weeks ago, but I don't think I can find that information now.
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Flang slang
Is it incorrect to say that David flung a stone at GoliathMokurai wrote:
It is incorrect to say that Zeta Oph was "flung out" of its binary system when its companion exploded. It simply continued at the same speed it had in orbit, in the direction it was going when the supernova blew past it. This is just Newton's First Law:An object in motion tends to remain in motion in a straight line.
fling (v.) c. 1300, "to dash, run, rush," probably from or related to Old Norse flengja "to flog," which is of uncertain origin, perhaps from Proto-Germanic *flang- (source also of Old Swedish flenga "strike," Danish flænge "slash, gash"). Meaning "to throw, cast, hurl" is from mid-14c. Related: Flung; flinging, but in Middle English with past tense flang, past participle flungen.
Art Neuendorffer
Re: APOD: Zeta Oph: Runaway Star (2017 Apr 08)
Superimposed over a DSS2 image (from Wikisky: blue/red/near infrared) of the same area, it is made obvious how different the Spitzer Space Telescope sees things than a ground based survey does. Not just the brightness of Zeta, but also the invisibility of that nebulosity in the DSS2 plates, which is so prominent in the APOD.APOD Robot wrote:The image spans about 1.5 degrees or 12 light-years at the estimated distance of Zeta Ophiuchi.
Wikipedia has an interesting article about Beta Scorpii, in that it is a system with no less than six stars. β¹ would then be a subgroup of three stars. The article also mentions the common origin of the Scorpius-Centaurus Association of stars.Ann wrote:The velocity of Zeta Ophiuchi is probably measured either relative to the Sun, or, perhaps more likely, relative to other stars at more or less the same distance from us in more or less the same part of the sky. Zeta (ζ) Ophiuchi is moderately close to Beta1 (β) Scorpii, Graffias, in the sky. The two stars belong to very similar spectral classes and are at relatively similar distances from us. It's just possible that these two stars are related.
They have very different proper motions, which makes sense if one of them is a runaway star.
Re: APOD: Zeta Oph: Runaway Star (2017 Apr 08)
Thanks, Case, that is a brilliant "image comparison"!Case wrote:Superimposed over a DSS2 image (from Wikisky: blue/red/near infrared) of the same area, it is made obvious how different the Spitzer Space Telescope sees things than a ground based survey does. Not just the brightness of Zeta, but also the invisibility of that nebulosity in the DSS2 plates, which is so prominent in the APOD.APOD Robot wrote:The image spans about 1.5 degrees or 12 light-years at the estimated distance of Zeta Ophiuchi.
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Re: APOD: Zeta Oph: Runaway Star (2017 Apr 08)
I agree Ann. Very well done CaseAnn wrote:Thanks, Case, that is a brilliant "image comparison"!
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Re: APOD: Zeta Oph: Runaway Star (2017 Apr 08)
The nebulosity in the Spitzer image is also visible in the optical if someone took a deep narrowband image with Ha and OIII. It is true most bowshocks are infrared only.Case wrote:Superimposed over a DSS2 image (from Wikisky: blue/red/near infrared) of the same area, it is made obvious how different the Spitzer Space Telescope sees things than a ground based survey does. Not just the brightness of Zeta, but also the invisibility of that nebulosity in the DSS2 plates, which is so prominent in the APOD.APOD Robot wrote:The image spans about 1.5 degrees or 12 light-years at the estimated distance of Zeta Ophiuchi.
Wikipedia has an interesting article about Beta Scorpii, in that it is a system with no less than six stars. β¹ would then be a subgroup of three stars. The article also mentions the common origin of the Scorpius-Centaurus Association of stars.Ann wrote:The velocity of Zeta Ophiuchi is probably measured either relative to the Sun, or, perhaps more likely, relative to other stars at more or less the same distance from us in more or less the same part of the sky. Zeta (ζ) Ophiuchi is moderately close to Beta1 (β) Scorpii, Graffias, in the sky. The two stars belong to very similar spectral classes and are at relatively similar distances from us. It's just possible that these two stars are related.
They have very different proper motions, which makes sense if one of them is a runaway star.
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Re: APOD: Zeta Oph: Runaway Star (2017 Apr 08)
As bowshocks go, this one doesn't appear particularly violent. At least, that's the impression it gives me. This fits with its [the star's] velocity being not that extraordinarily fast.
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Re: APOD: Zeta Oph: Runaway Star (2017 Apr 08)
I'm not sure any bowshocks are really what I'd call "violent". They are slow, evolving over thousands to millions of years. Their densities are lower than the hardest vacuums we make in a lab. Really, it's just particles colliding with particles resulting in enough heat to produce rather high energy photons. But the total energy is small.BDanielMayfield wrote:As bowshocks go, this one doesn't appear particularly violent. At least, that's the impression it gives me. This fits with its [the star's] velocity being not that extraordinarily fast.
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Re: APOD: Zeta Oph: Runaway Star (2017 Apr 08)
https://apod.nasa.gov/apod/ap991127.html
https://apod.nasa.gov/apod/ap060120.html
https://apod.nasa.gov/apod/ap020313.html
https://apod.nasa.gov/apod/ap060130.html
https://apod.nasa.gov/apod/ap061124.html
https://apod.nasa.gov/apod/ap080522.html
https://apod.nasa.gov/apod/ap001128.html
https://apod.nasa.gov/apod/ap001025.html
https://apod.nasa.gov/apod/ap001017.html
https://apod.nasa.gov/apod/ap020624.html
https://apod.nasa.gov/apod/ap060120.html
https://apod.nasa.gov/apod/ap020313.html
https://apod.nasa.gov/apod/ap060130.html
https://apod.nasa.gov/apod/ap061124.html
https://apod.nasa.gov/apod/ap080522.html
https://apod.nasa.gov/apod/ap001128.html
https://apod.nasa.gov/apod/ap001025.html
https://apod.nasa.gov/apod/ap001017.html
https://apod.nasa.gov/apod/ap020624.html
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Re: APOD: Zeta Oph: Runaway Star (2017 Apr 08)
Thanks. Art's list of APOD bow shocks shows that most aren't all that "violent" looking either.Chris Peterson wrote:I'm not sure any bowshocks are really what I'd call "violent". They are slow, evolving over thousands to millions of years. Their densities are lower than the hardest vacuums we make in a lab. Really, it's just particles colliding with particles resulting in enough heat to produce rather high energy photons. But the total energy is small.BDanielMayfield wrote:As bowshocks go, this one doesn't appear particularly violent. At least, that's the impression it gives me. This fits with its [the star's] velocity being not that extraordinarily fast.
Since "violent" really doesn't fit I'm a bit perplexed as to what word to use make my point. The bend in Zeta Oph's bow shock appears rather gently flowing instead of the sharp bends of some bow shocks that rap around the stars that cause them.
Art's list did have one example of a rather violent looking bow shock:
But BZ Cam is a scene of some violence, since it is a cataclysmic variable. Its bow has a violent bend to it too. Another comparable use of the word violent would be the golf expression "violent lip-out", sometimes followed by violence being inflicted upon one's putter.neufer wrote:https://apod.nasa.gov/apod/ap001128.html
Bruce
Last edited by BDanielMayfield on Mon Apr 10, 2017 6:34 pm, edited 1 time in total.
Just as zero is not equal to infinity, everything coming from nothing is illogical.
Re: APOD: Zeta Oph: Runaway Star (2017 Apr 08)
Ultraviolet bow shock and tail of cool star Mira.
Photo: GALEX.
Photo: GALEX.
Mira's got a splendid tail, too.
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