<p>The term you're searching for is probably <em><a href="https://en.wikipedia.org/wiki/Accretion_%28astrophysics%29" rel="noreferrer">accretion</a></em> (I guess it might sound similar to <em>a kerzan</em> if the speaker had a cold or the listener couldn't hear it well enough for other reasons). This term is not limited to close binary stars (accreting binaries) cannibalizing each other because they orbit each other at such proximity that the L<sub>1</sub> <a href="https://en.wikipedia.org/wiki/Lagrangian_point" rel="noreferrer">Lagrange point</a> between them extends into their own <a href="https://en.wikipedia.org/wiki/Roche_lobe" rel="noreferrer">Roche lobe</a>, they form accretion disks connected through an accretion stream, and they feed off each other (thus why this is often referred to as cannibalism):</p>

<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<img src="https://i.sstatic.net/uTv0Z.jpg" alt="enter image description here"></p>

<p>&nbsp;&nbsp;&nbsp;<sup>Artist's conception shows an accreting binary at the center of the globular cluster NGC 6624 (Source: <a href="http://csep10.phys.utk.edu/astr162/lect/binaries/accreting.html" rel="noreferrer">U. of Tennessee AstroWiki</a>)</sup></p>

<p>Some examples of accreting binaries are <a href="https://en.wikipedia.org/wiki/Symbiotic_variable_star" rel="noreferrer">symbiotic novae</a>, <a href="https://en.wikipedia.org/wiki/X-ray_binary" rel="noreferrer">X-ray binaries</a>, <a href="https://en.wikipedia.org/wiki/X-ray_binary#Microquasar" rel="noreferrer">microquasars</a>, <a href="https://en.wikipedia.org/wiki/X-ray_pulsar" rel="noreferrer">X-ray pulsars</a>, and so on. See links for more examples and explanations. Other examples of accretion include <a href="http://www.nasa.gov/mission_pages/hubble/science/planet-eater.html" rel="noreferrer">stellar accretion of planetary materials of a planet in a low altitude orbit around its parent star</a>, formation of planets via accretion of materials of the <a href="https://en.wikipedia.org/wiki/Protoplanetary_disk" rel="noreferrer">protoplanetary disk</a>, <a href="https://en.wikipedia.org/wiki/Active_galactic_nucleus" rel="noreferrer">active galactic nucleus</a> (AGN) like <a href="https://en.wikipedia.org/wiki/Quasar" rel="noreferrer">quasars</a> (could also sound similar), <a href="https://en.wikipedia.org/wiki/Nova" rel="noreferrer">novae</a>, and e.g. the <a href="http://www.sciencemag.org/content/262/5133/550.abstract" rel="noreferrer">Earth still accretes on average ~ 110 metric tons of new materials per day</a>, too.</p>

CC BY-SA 3.0
2014-04-22T01:06:02.440Z
Curious, what would happen if hypothetically the two stars weren't close but were on a direct collision course with each other?
TheBluegrassMathematician
CC BY-SA 3.0
2014-04-22T01:38:56.307Z
May explode as a supernova. May generate a black hole. May create a bunch of planets. There are many possible outcomes. http://en.wikipedia.org/wiki/Stellar_collision
Florin Andrei
CC BY-SA 3.0
2014-04-21T23:05:18.557Z
2014-04-21T23:24:03.427Z
2014-04-21T23:24:03.427Z
TildalWave
<p>Is it possible you refer to a <a href="https://en.wikipedia.org/wiki/Thorne%E2%80%93%C5%BBytkow_object" rel="nofollow noreferrer">Thorne–Żytkow object</a> ? 
This is literally a star within another star, more specifically a compact object (Neutron star) inside a giant star (red giant or supergiant).</p>

<p><img src="https://i.sstatic.net/WmKSM.gif" alt="enter image description here"></p>

<p>As far as I know, this is an only theoretical object, it has never been observed.</p>

<p>In the <a href="http://adsabs.harvard.edu/doi/10.1086/155109" rel="nofollow noreferrer">original paper</a> from the authors, they provide some observable characteristics of these objects, like some peculiar emission lines. You can imagine the chemistry of such an object would be really unique.</p>

<p>Here an article for a possible identification <a href="http://phys.org/news/2014-01-discovery-thorne-zytkow.html" rel="nofollow noreferrer">link 1</a>, very recent work (2014).</p>

<p>And here some calculations <a href="http://cow.physics.wisc.edu/~ogelman/guide/tz/" rel="nofollow noreferrer">link2</a>.</p>

CC BY-SA 3.0
2016-08-22T05:41:44.603Z
@Py-ser   case A:  a TZO with a black hole instead of a NS. case B: a bh penetrates a star.
questionhang
CC BY-SA 3.0
2014-04-22T01:26:14.223Z
So when this thing goes supernova, what happens to the neutron star? And what about black hole formation? But I must say that is one of the cooler things that I've seen.
TheBluegrassMathematician
CC BY-SA 3.0
2014-04-22T01:39:20.710Z
"What" goes supernova? :) You have two different objects here. One of them is already collapsed.
Py-ser
CC BY-SA 3.0
2014-04-22T01:52:56.770Z
Well definitely the red giant. It's going to collapse in on itself so what does that mean for the inner neutron star? Is it super compressed into a black hole?
TheBluegrassMathematician
CC BY-SA 3.0
2014-04-22T02:52:30.553Z
@Py-ser Yes,TZO is what I heard. I do not know why there is not an accretion disk formed. Because generally there is angular momentum and a disk is necessary.
questionhang
CC BY-SA 3.0
2014-04-22T02:57:31.993Z
@Py-ser do you know any similar paper that study how a small black hole goes through a star?
questionhang
CC BY-SA 3.0
2014-04-22T03:00:55.623Z
These are different questions: 1) why do you need an accretion disk here? The dynamic is different.. 2) I don't know what you mean by "black hole goes through a star". Do you mean a TZO with a black hole instead of a NS?
Py-ser
CC BY-SA 3.0
2015-08-18T14:28:27.503Z
A paper was released shortly after your answer on the observation of a likely TZO candidate: http://mnrasl.oxfordjournals.org/content/443/1/L94
user4815162342
CC BY-SA 3.0
2014-04-22T01:17:54.173Z
2014-04-22T04:34:40.230Z
2014-04-22T04:34:40.230Z
Py-ser
<p>A star <em>A</em> goes through the body of another star <em>B</em>, or is swallowed by <em>B</em>. There is no tidal disruption.</p>

<p>It sounds like <em>kerzan</em>. Does anybody recognise this pronunciation?</p>

CC BY-SA 3.0
2014-04-22T01:27:12.657Z
Were you listening to somebody with a southern drawl say this?
TheBluegrassMathematician
CC BY-SA 3.0
2014-04-22T03:05:25.580Z
He just forgot its pronunciation. You can take a look at Py-ser's post below.
questionhang
<star><terminology>
What is the term for a star swallowing another star?
questionhang
# What is the term for a star swallowing another star?

(Asked by: username_0 on 2014-04-21)

A star *A* goes through the body of another star *B*, or is swallowed by *B*. There is no tidal disruption.

It sounds like *kerzan*. Does anybody recognise this pronunciation?

**Tags:** star, terminology
> **Comments:**
> **username_1**: Were you listening to somebody with a southern drawl say this?  
> **username_0**: He just forgot its pronunciation. You can take a look at Py-ser's post below.  

---

## 2 answers

### Answer by username_2 on 2014-04-21. Score: 6

The term you're searching for is probably *[accretion](https://en.wikipedia.org/wiki/Accretion_%28astrophysics%29)* (I guess it might sound similar to *a kerzan* if the speaker had a cold or the listener couldn't hear it well enough for other reasons). This term is not limited to close binary stars (accreting binaries) cannibalizing each other because they orbit each other at such proximity that the L1 [Lagrange point](https://en.wikipedia.org/wiki/Lagrangian_point) between them extends into their own [Roche lobe](https://en.wikipedia.org/wiki/Roche_lobe), they form accretion disks connected through an accretion stream, and they feed off each other (thus why this is often referred to as cannibalism):

![enter image description here](https://i.sstatic.net/uTv0Z.jpg)

Artist's conception shows an accreting binary at the center of the globular cluster NGC 6624 (Source: [U. of Tennessee AstroWiki](http://csep10.phys.utk.edu/astr162/lect/binaries/accreting.html))

Some examples of accreting binaries are [symbiotic novae](https://en.wikipedia.org/wiki/Symbiotic_variable_star), [X-ray binaries](https://en.wikipedia.org/wiki/X-ray_binary), [microquasars](https://en.wikipedia.org/wiki/X-ray_binary#Microquasar), [X-ray pulsars](https://en.wikipedia.org/wiki/X-ray_pulsar), and so on. See links for more examples and explanations. Other examples of accretion include [stellar accretion of planetary materials of a planet in a low altitude orbit around its parent star](http://www.nasa.gov/mission_pages/hubble/science/planet-eater.html), formation of planets via accretion of materials of the [protoplanetary disk](https://en.wikipedia.org/wiki/Protoplanetary_disk), [active galactic nucleus](https://en.wikipedia.org/wiki/Active_galactic_nucleus) (AGN) like [quasars](https://en.wikipedia.org/wiki/Quasar) (could also sound similar), [novae](https://en.wikipedia.org/wiki/Nova), and e.g. the [Earth still accretes on average ~ 110 metric tons of new materials per day](http://www.sciencemag.org/content/262/5133/550.abstract), too.

> **Comments:**
> **username_1**: Curious, what would happen if hypothetically the two stars weren't close but were on a direct collision course with each other?  
> **username_3**: May explode as a supernova. May generate a black hole. May create a bunch of planets. There are many possible outcomes. http://en.wikipedia.org/wiki/Stellar_collision  

---

### Answer by username_4 on 2014-04-22. Score: 4

Is it possible you refer to a [Thorne–Żytkow object](https://en.wikipedia.org/wiki/Thorne%E2%80%93%C5%BBytkow_object) ?
This is literally a star within another star, more specifically a compact object (Neutron star) inside a giant star (red giant or supergiant).

![enter image description here](https://i.sstatic.net/WmKSM.gif)

As far as I know, this is an only theoretical object, it has never been observed.

In the [original paper](http://adsabs.harvard.edu/doi/10.1086/155109) from the authors, they provide some observable characteristics of these objects, like some peculiar emission lines. You can imagine the chemistry of such an object would be really unique.

Here an article for a possible identification [link 1](http://phys.org/news/2014-01-discovery-thorne-zytkow.html), very recent work (2014).

And here some calculations [link2](http://cow.physics.wisc.edu/~ogelman/guide/tz/).

> **Comments:**
> **username_1**: So when this thing goes supernova, what happens to the neutron star? And what about black hole formation? But I must say that is one of the cooler things that I've seen.  
> **username_4**: "What" goes supernova? :) You have two different objects here. One of them is already collapsed.  
> **username_1**: Well definitely the red giant. It's going to collapse in on itself so what does that mean for the inner neutron star? Is it super compressed into a black hole?  
> **username_0**: @Py-ser Yes,TZO is what I heard. I do not know why there is not an accretion disk formed. Because generally there is angular momentum and a disk is necessary.  
> **username_0**: @Py-ser do you know any similar paper that study how a small black hole goes through a star?  
> **username_4**: These are different questions: 1) why do you need an accretion disk here? The dynamic is different.. 2) I don't know what you mean by "black hole goes through a star". Do you mean a TZO with a black hole instead of a NS?  
> **username_5**: A paper was released shortly after your answer on the observation of a likely TZO candidate: http://mnrasl.oxfordjournals.org/content/443/1/L94  
> **username_0**: @Py-ser   case A:  a TZO with a black hole instead of a NS. case B: a bh penetrates a star.  

---

