Questions tagged [binary-star]

Question regarding a pair of stars that are gravitationally linked and orbit around their barycenter.

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28
votes
3answers
5k views

Why are there so many binary systems?

Most star systems are binary, but why is that? Why would new stars form close to others, and not (relatively) evenly spread? And even if they are clustered close together, why are the majority binary? ...
28
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1answer
4k views

How far apart are stars in a binary system?

I'm wondering how far apart from one another the stars are in binary systems. What is the distribution of the separation between binary stars? Are most of the binary stars very far apart like Sirius (...
26
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2answers
872 views

Amateur observing targets for binary star systems?

Are there any easily resolvable, binary star, observing targets visible from ~N40°? I'd like to be able to show, in one observing session, Mizar and Alcor (naked eye resolvable), another with ...
25
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4answers
3k views

Are there any double stars that I can actually see orbit each other?

If I had a nice amateur telescope†, are there any multiple star systems that I could observe over a few years or a few decades and actually see the movement of one or both of them over time? My short ...
18
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2answers
7k views

Is Sun a part of a binary system?

Does our Sun have a counterpart, i.e., is it a part of a binary-system? If so, how does the other star look like and where is it?
18
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2answers
630 views

How many stars can stay close to each other without collapsing?

Is it possible for two stars to exist close to each other? "Close" is relative; let's assume that two stars are close to each other if they are at the center of the same solar system. It's ...
18
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2answers
547 views

What are the current observational constraints on the existence of Nemesis?

Nemesis is a hypothetical companion to the Sun on a very eccentric, long-period orbit. The star supposedly returns every few tens of millions years, driving comets into the inner solar system and ...
14
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1answer
190 views

Mechanisms of binary/multiple star formation

What are mechanisms of binary/multiple star formation in different mass ranges (low, intermediate and high stellar masses)?
13
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1answer
3k views

Why can't our Sun be a binary with Jupiter as a T or Y dwarf?

I just learned about Brown Dwarfs, they are "failed" stars, they narrowly missed the stellar mass mark. I learned that Y Dwarfs have temperature as low as 80 Fahrenheit (The first one found by WISE ...
13
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4answers
3k views

Will Sirius B start accreting from A and become a supernova type Ia?

Sirius B is a massive white dwarf of 1 Solar mass, orbiting at about 25 AU distance from the 2 Solar mass Sirius A. As it evolves and expands, will the A star start shedding matter to the white dwarf, ...
13
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2answers
2k views

How are binary star systems created?

I don't know how common it is for a system to have two stars (or perhaps even more) but how do they arise? Is that due to the stellar accretion disc, or the composition of the stellar nebula? Or are ...
11
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1answer
2k views

Orbits in a binary star system

I know of three sets of stable orbits in a binary star system: orbiting closely around star A, orbiting closely around star B, or orbiting distantly around both stars (and their mutual center of ...
9
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1answer
134 views

V471 Tauri's circumbinary brown dwarf non-observation; Applegate, or over-restrictive assumptions?

tl;dr Has the brown dwarf observation been disproven? I have just started reading about the interesting object V471 Tauri. The first two sentences of the introduction to The V471 Tauri System: A ...
8
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2answers
1k views

How many actual stars are Polaris?

I am getting conflicting accounts everywhere. I heard astronomers saying Polaris is a 3-star system. Some say they are binary but are optical-doubled with a 3rd. ...
8
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2answers
2k views

Multiple Star-system percentages

What are the percentages of systems that have x number of stars in them? What I have found thus far is something like: Single Star Sytems = 69% Double Star Systems = ~10% Triple Star Systems = <...
8
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2answers
880 views

How long does an over contact binary star system last?

I read recently about VFTS 352, an overcontact binary star system where both stars have roughly equal mass. All of the reports I've read (in mass-media type publications) have said that the system has ...
8
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1answer
294 views

How can I measure the mass of eclipsing binary stars?

Is there any method to measure the mass of eclipsing binaries without using Doppler shift effect?
8
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1answer
100 views

Why do X-ray binaries such as GRS-1915 have active and quiet states?

X-ray binaries such as GRS-1915 feature a black hole and a regular star. The x-ray luminosity is likely related to the rate of mass flow into the black hole from the star so when there is a lot of ...
7
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1answer
173 views

What determines the configuration of orbits in a binary system?

There are essentially two configurations of orbits a system with two bodies can have: A configuration where the paths do not cross: A configuation where the paths cross: Note: Size of the bodies ...
7
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2answers
1k views

How to plot orbit of binary star and calculate its orbital elements?

I have a set of dates, position angles ($\theta$) and angular separations ($\rho$) for visual binary star. For example: ...
6
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3answers
2k views

Binaries consisting of a black hole and a non-black hole?

Are there any known binary systems in which one member is a black hole and the other is not a black hole (main sequence star, giant, neutron star, white dwarf, whatever)? Googling seems to turn up ...
6
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1answer
3k views

What percentage of visual stars are actually binary stars?

I know this is such a thing as a binary star where for example two stars rotate around a central point of gravity but to the naked eye are just a star. What I do not know is how common this is (...
6
votes
2answers
416 views

What's the name for [the other kind of planet] in a binary star system?

This XKCD what-if talks about rainbows on planets in a binary star system. It points out that there are two types: circumbinary planets, where the planet orbits far from and around both stars [the ...
6
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3answers
160 views

What is the spectral reflectance of starlight in a close binary?

Ignore the Blender Monkey! (from here) In a close-orbiting binary pair, a small but significant fraction of the light from each star falls upon the other, and the result has to be carefully modeled ...
6
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1answer
277 views

Doing Correct Calculations with Binary Star Systems

I've been experimenting with Binary Star System calculations but came across some issues. I can correctly calculate the Semi-Major Axis of the Earth's orbit around the Sun by doing the equation: ...
6
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1answer
10k views

How can I calculate the orbital periods in a binary star system?

I have two stars, with known masses and known orbital radius. How do I calculate the orbital periods of both stars?
6
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2answers
305 views

What happens when a star gets hit by a supernova?

This may sound like a strange question, but say that two stars are relatively next to one another in a binary star system, what would happen to one of the stars if the other went supernova? Would it ...
6
votes
1answer
165 views

Is it possible for two stars to be in a horseshoe orbit around a much larger star?

I was reading about how Saturn has two moons, Janus and Epimetheus, that swap orbits once every four years. Could something like this happen on a much larger scale, but with stars instead of a planet ...
6
votes
1answer
390 views

How can we tell that a short-period binary is tidally locked?

Observationally, how can this be established? What is known theoretically about the process? Are there any reference papers to read?
6
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1answer
144 views

How do isolated binary compact systems survive their formational supernovae?

In a broad sense I'm trying to understand how a binary black hole or neutron star systems can form from isolated binary massive star systems (i.e., other than from migration within rich BH/NS clusters)...
6
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0answers
209 views

Questions about a fictional binary system, and habitability [closed]

Note: Questions are at the bottom. The rest had simply been written in a format to better organize my thoughts. The formulas used to construct this fictional solar system, had been borrowed from ...
5
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1answer
136 views

Why is a giant planet around a tiny star unusual when binary stars are normal?

Inspired by this BBC article and the corresponding journal article about the M dwarf star GJ 3512. The Jupiter-like world is unusually large compared with its host star, contradicting a widely held ...
5
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1answer
140 views

How does a planet lose mass to its host star?

How do bodies like WASP-12b lose mass to its central body? The process is never really explained in popular media, instead showing visualisations of a thin veil of gas being "sucked" in a rather ...
5
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4answers
2k views

Hulse Taylor Binary Pulsar - How is “Cumulative Periastron Time shift” calculated?

Following on from a previous question about the interesting Hulse Taylor Binary Pulsar. BACKGROUD Weisberg & Taylor, 2004 present a graph showing the change in "Cumulative Periastron Time Shift" ...
5
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2answers
186 views

Why are so many sun-like stars found in multiple systems? How do planets form in such a situation?

It has been reported that perhaps half of nearby sun-like stars are found in multiple systems. Why is this so common, and how do planets form in such a situation? Kaitlin M. Kratter, “Sibling ...
4
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2answers
90 views

Binary Star Initial Speed

I am writing a 2D simulation for binary stars orbiting each other. Currently, the initial position of the stars are on opposite sides of the screen with the left star having a velocity up the page and ...
4
votes
2answers
146 views

How many exoplanets have been found around binary stars?

This XKCD whatif talks about circumbinary and [the other kind of] exoplanets. How many such exoplanets have actually been discovered? I tried to look it up at exoplanets.org, but didn't find a column ...
4
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1answer
334 views

How bright was Scholz when is passed near the Sun 70,000 years ago?

I just read that a star called Scholz passed only 0.8 years-light away from us 70,000 years ago. It is a red dwarf. I don´t know how bright it was in the night sky. Does someone know how bright it ...
4
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1answer
58 views

Does binarity play a role in spectral fitting?

Most of the spectroscopic surveys like SDSS classify stars into one pure spectral type. However, a large fraction of stars are in binaries. Can we know whether a spectral fitting is good enough? Is ...
4
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2answers
77 views

Observing eclipsing binaries

In a matter of weeks, I will be performing my first observation using a 25-cm Newton telescope (+CCD camera) and would be grateful for advice regarding an otherwise basic research that I have decided ...
4
votes
1answer
91 views

Where does Love's number come from in $\delta m = \frac{1}{2}k_2M_2\lbrace\frac{R_1}{r_\star}\rbrace^3$, the formula for the mass of a tidal bulge?

My question refers to page 165 of this paper. Specifically, how does one derive the equation $\delta m = \frac{1}{2}k_2M_2\lbrace\frac{R_1}{r_\star}\rbrace^3$ for the mass of a tidal bulge? A full ...
4
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1answer
178 views

Do planets form around lone stars, multiple stars, or both? Do we know this yet?

Since about 1990 astronomers been able to detect planets around other stars, using a couple different techniques, which is amazing. By this point, do we know whether planets form only around single ...
4
votes
1answer
116 views

Why do spectroscopic binaries have approximate circular orbits?

So for an assignment I have to answer the question what I can conclude concerning the shape of the orbit, knowing that it is both an eclipsing and spectroscopic binary. Now, I think the answer I ...
4
votes
1answer
272 views

How can a supernova affect black hole in a binary system?

Suppose in a binary stars system there is a dying star and a companion black hole as they orbit around each other. My question is what will possibly happen to the black hole if the partner goes ...
4
votes
2answers
257 views

Double Planet Orbiting Wide Binary Star?

Right now I'm writing a sci-fi story that develops in a double planet. But that's not all, the double planet (along with a couple more planets) orbit a big star and the whole system is orbited by ...
4
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0answers
35 views

Is Beta Lyrae still thought to be losing mass in a spiral outflow?

In the famous 1960 painting by Chesley Bonestell, Beta Lyrae is depicted with a glowing spiral trail of matter emanating from the binary stars. I'm wondering if that's still thought to be a ...
3
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2answers
48 views

Night-Day Cycles in S-Type Planetary Systems

I am a writer and space enthusiast. For a story I am currently writing I would like to have a planet which orbits a star which resembles the sun, which in turn orbits another star. In this situation ...
3
votes
2answers
432 views

Black dwarf binary systems

I know black dwarf stars do not exist yet, and that they are what white dwarfs end up after a long time. The question is really simple: would it be possible to have a binary system in which one of the ...
3
votes
1answer
59 views

Total apparent magnitude of eclipsing binary system

This is a question from the 2016 USAAAO national exam, for which no solutions are given: An eclipsing binary system has a magnitude $m_p$ = 14.2 during the primary transit and $m_s$ = 13.7 during ...
3
votes
1answer
255 views

Can a binary star optically “orbit” a planet?

I was watching a science fiction anime from the mid 70's. In it, there was a star orbiting a planet. Since this seemed impossible, and I had never heard of it, I looked on the internet to see if this ...