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Questions tagged [binary-star]

Questions regarding a pair of stars that are gravitationally bound and orbit around their barycenter.

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30 votes
1 answer
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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 (...
usernumber's user avatar
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29 votes
3 answers
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? ...
RonS's user avatar
  • 577
27 votes
2 answers
1k 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 ...
Craig Constantine's user avatar
25 votes
4 answers
4k 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 ...
uhoh's user avatar
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20 votes
2 answers
8k 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?
stp30's user avatar
  • 575
18 votes
2 answers
906 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 ...
Zoltán Schmidt's user avatar
17 votes
2 answers
745 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 ...
Guillochon's user avatar
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15 votes
1 answer
209 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)?
user2579566's user avatar
14 votes
2 answers
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 ...
Marijn 's user avatar
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13 votes
1 answer
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 ...
fahadash's user avatar
  • 501
13 votes
4 answers
4k 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, ...
LocalFluff's user avatar
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12 votes
1 answer
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 ...
Mark's user avatar
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11 votes
2 answers
2k views

How would a person know if a planet is orbiting a binary star?

I read in Neil deGrasse Tyson's book Astrophysics for People in a Hurry that scientists can tell if a star has a planet orbiting it because the light appears to shake. So if in the case of a binary ...
Tardy's user avatar
  • 255
10 votes
3 answers
2k views

Are multiple stars actually more common than singles?

In the book by Neil Tyson & Michael A. Strauss & J. Richard Gott titled "Welcome to the Universe: An Astrophysical Tour" there is a sentence that starts: "Since more than half ...
Jimmy Bionic's user avatar
10 votes
2 answers
4k 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 = <...
Durakken's user avatar
  • 397
10 votes
1 answer
193 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 ...
uhoh's user avatar
  • 30.6k
9 votes
3 answers
3k 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 ...
user avatar
9 votes
1 answer
824 views

Metallicity in gravitational wave astronomy

Metallicity relates to the quantity of elements in an object that are heavier than hydrogen and helium. I often see this terminology in recent studies of gravitational waves such as this paper. If I ...
Junaid Ihsan's user avatar
9 votes
2 answers
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. ...
fahadash's user avatar
  • 501
9 votes
1 answer
1k views

What do the words "p-type" and "s-type" mean?

As explained in various sources (such as that answer), a planet in an s-type orbit orbits one of the stars of a binary star system, whereas a planet in a p-type orbit orbits both stars. A synonym for ...
O. R. Mapper's user avatar
9 votes
1 answer
656 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?
user2427168's user avatar
8 votes
1 answer
534 views

Post-Keplerian orbital parameters; is there a generally accepted set with definitions?

Strong-Field Gravity Tests with the Double Pulsar is a pretty big deal! 16 years of precision timing including "timing parallax" via VLBI has provided a dataset for which analysis requires (...
uhoh's user avatar
  • 30.6k
8 votes
2 answers
1k 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 ...
yshavit's user avatar
  • 183
8 votes
1 answer
195 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 ...
HDE 226868's user avatar
  • 36.6k
8 votes
1 answer
511 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?
questionhang's user avatar
  • 3,137
7 votes
2 answers
651 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 ...
ThePopMachine's user avatar
7 votes
1 answer
266 views

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

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 ...
Harry Johnston's user avatar
7 votes
2 answers
177 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 ...
Spikes's user avatar
  • 71
7 votes
1 answer
506 views

How far is the nearest (known) black hole from our solar system? Is there an official list?

Which is the nearest known or suspected black hole from the Solar System and how far is it from us? Is there an easily-viewed catalog that astronomers use to keep track of these?
Gaurav Mody's user avatar
7 votes
1 answer
101 views

What does it mean for something to be optically thick to pair production?

I have seen several references in the high energy astrophysics literature (including the example below) which make reference to an astronomical source being "thick to pair production". What ...
georgeamccarthy's user avatar
7 votes
1 answer
268 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 ...
Gliese's user avatar
  • 831
7 votes
2 answers
2k 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: ...
user2579566's user avatar
7 votes
1 answer
136 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 ...
ehsteve's user avatar
  • 1,154
7 votes
1 answer
90 views

Meaning of Bidirectional Arrow in a Fitting Formula

I was reading this paper on the ejecta mass of compact binary mergers and came across this notation in equation (6): $$\frac{M_\text{dyn}}{10^{-3}M_\odot}=\left(\frac{a}{C_1}+b\frac{M_2^n}{M_1^n}+cC_1\...
hikari30's user avatar
7 votes
0 answers
252 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 ...
platypus-rising's user avatar
6 votes
1 answer
802 views

Effects of a binary star system on a tidally locked planet

This is basically a world-building question, but I'm looking for a scientifically based answer, so I'm posting here. Imagine a fairly earth-like planet- Lets call it Planet X. Planet X has an earth-...
user1642529's user avatar
6 votes
1 answer
5k 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 (...
esé's user avatar
  • 327
6 votes
1 answer
518 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 ...
Carlos's user avatar
  • 493
6 votes
1 answer
138 views

Fate of a planet orbiting a Lagrange point behind a star?

Let's say there is a planet orbiting at L5 behind a star, which is in turn orbiting a more massive star, like so: What is the ultimate fate of this planet? I'm predicting that it will spiral into the ...
slowerthanstopped's user avatar
6 votes
3 answers
254 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 ...
uhoh's user avatar
  • 30.6k
6 votes
1 answer
807 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: ...
chriscrutt's user avatar
6 votes
2 answers
630 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 ...
C. Jordan's user avatar
  • 235
6 votes
1 answer
251 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)...
Stilez's user avatar
  • 1,022
5 votes
1 answer
388 views

Do main sequence stars in binaries transfer mass by Roche lobe overflow?

It is known that binary star components containing red giant can under go mass transfer when their radii exceeds the Roche limt. Do main sequence binary stars also undergo mass transfer by this ...
Jiswin's user avatar
  • 177
5 votes
1 answer
650 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 ...
Pablo's user avatar
  • 1,113
5 votes
1 answer
402 views

What's the meaning of "hard supermassive black hole binary"?

In this paper, the authors state in the Introduction that A hard SMBHB [SuperMassive Black Hole Binary] can eject surrounding stars to transfer their orbital energy and angular momentum, which may be ...
Jim421616's user avatar
  • 2,568
5 votes
1 answer
258 views

Which binary star system has a greatest angular distance?

Visible from the Earth, which binary star system has greatest angular distance ?
user3715778's user avatar
5 votes
1 answer
11k 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?
aaazalea's user avatar
  • 159
5 votes
1 answer
295 views

How would you calculate the "day" on a planet orbiting a red dwarf that is a companion to a larger star?

So the idea is you have an Earth-sized planet with a moon orbiting an M-class star (let's give it .25 solar masses) at 0.2 AU, with an orbital period of 63 days and a 24-hour day. Its orbit has an ...
PrincipledStarfish's user avatar
5 votes
1 answer
71 views

Did de Sitter expect to disprove Ritz theory only with visual binaries?

Walter Ritz’s emission theory stated that some fraction of the velocity of an object was added to the speed of light emitted from it. Willem de Sitter pointed out a problem with this in the case of a ...
D R Ball's user avatar

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