Starship Asterisk*

At the Heart of Orion

Explanation: Near the center of this sharp cosmic portrait, at the heart of the Orion Nebula, are four hot, massive stars known as the Trapezium. Tightly gathered within a region about 1.5 light-years in radius, they dominate the core of the dense Orion Nebula Star Cluster. Ultraviolet ionizing radiation from the Trapezium stars, mostly from the brightest star Theta-1 Orionis C powers the complex star forming region's entire visible glow. About three million years old, the Orion Nebula Cluster was even more compact in its younger years and a dynamical study indicates that runaway stellar collisions at an earlier age may have formed a black hole with more than 100 times the mass of the Sun. The presence of a black hole within the cluster could explain the observed high velocities of the Trapezium stars. The Orion Nebula's distance of some 1,500 light-years would make it the closest known black hole to planet Earth.

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My favorite place, off planet... is getting more interesting....

I wish we had warmer weather when it is in our Winter Skies...

:---[===] *

"The presence of a black hole within the cluster could explain the observed high velocities of the Trapezium stars."
That begs the question of the Trapezium's motions relative to the cloud itself and to each other.

For a 100-150 solar mass black hole to be lurking in the cloud, the Trapezium's neighborhood looks quite placid. Compare it to the Milky's Way's Arches near the center which are almost certainly hole-formed, and said to be ~4M in mass if a black hole. The Arches are a large-scale structure.
http://www.skyandtelescope.com/wp-conte ... _341px.jpg
http://www.skyandtelescope.com/astronom ... -in-orion/

Have the Charles University researchers ran their simulation against globular clusters? far more crowded than Orion could have been in star population?

100-150 solar masses would be an intermediate-sized black hole. Nowhere does Orion exhibit the orbital order as say 47 Tucanae, or even artifacts suggestive of its past presence.
http://www.skyandtelescope.com/wp-conte ... 1000px.jpg

http://www.skyandtelescope.com/astronom ... lack-hole/

"Kızıltan and his colleagues first built a realistic model of 47 Tucanae. Then, they measured the locations of 25 pulsars throughout the globular cluster.
.. The pulsars, they found, are on the move. They’re spinning around the center of the cluster rapidly — too rapidly given the number of central stars alone."

Orion's environment gives the appearance of being relatively relaxed compared to an environment of a black hole.

"Radio/optical composite of the Orion Molecular Cloud Complex showing the OMC-2/3 star-forming filament. GBT [Green Bank Telescope] data is shown in orange."
https://public.nrao.edu/images/non-gall ... mpWide.jpg

"Zoom in of the OMC-2/3 region."
https://public.nrao.edu/images/non-gall ... o_Comp.jpg

https://public.nrao.edu/news/pressrelea ... ains-orion

This article suggests many of the stars at the heart of Orion are very young. Runaway collisions vs. youth.

"The Trapezium Cluster at the nebula's center contains more than 1,500 stars."

"This estimate, combined with the fact that we don't see any evidence for depletion of the protoplanetary disks, even those exposed to the highest radiation levels, suggests that the central stars are even younger, perhaps only a few tens of thousands of years old," O'Dell says."

Surely stars that young would point to a black hole's presence by more than relative speed, alone?

http://exploration.vanderbilt.edu/news/ ... on.htm#top

And to counter the researchers' argument of the Trapezium stars' speeds indicating a black hole's presence, I suppose these "bullets" would suggest so, too? Some unknown violent process.

http://www.gemini.edu/node/226

"The Orion bullets were first seen in a visible-light image in 1983. By 1992, images taken at infrared wavelengths led astronomers to conclude that these clumps of gas were ejected from deep within the nebula following an unknown violent event connected with the recent formation of a cluster of massive stars there. The bullets are speeding outward from the cloud at up to 400 kilometers (250 miles) per second. [much faster than the Trapezium stars?] This is more than a thousand times faster than the speed of sound. The name "bullet" is somewhat misleading since these objects are truly gigantic. The typical size of one of the bullet tips is about ten times the size of Pluto's orbit around the Sun."

douglas wrote:"The presence of a black hole within the cluster could explain the observed high velocities of the Trapezium stars."
That begs the question of the Trapezium's motions relative to the cloud itself and to each other.

For a 100-150 solar mass black hole to be lurking in the cloud, the Trapezium's neighborhood looks quite placid. Compare it to the Milky's Way's Arches near the center which are almost certainly hole-formed, and said to be ~4M in mass if a black hole. The Arches are a large-scale structure.

What would you expect the neighborhood to look like if a black hole was there? And what are the "Milky Way's Arches"?

Chris Peterson wrote:...
And what are the "Milky Way's Arches"?

Arches Cluster ???

Chris Peterson wrote:

douglas wrote:"The presence of a black hole within the cluster could explain the observed high velocities of the Trapezium stars."
That begs the question of the Trapezium's motions relative to the cloud itself and to each other.

For a 100-150 solar mass black hole to be lurking in the cloud, the Trapezium's neighborhood looks quite placid. Compare it to the Milky's Way's Arches near the center which are almost certainly hole-formed, and said to be ~4M in mass if a black hole. The Arches are a large-scale structure.

What would you expect the neighborhood to look like if a black hole was there? And what are the "Milky Way's Arches"?

These arches?

Ann

Ann wrote:

Chris Peterson wrote:

douglas wrote:"The presence of a black hole within the cluster could explain the observed high velocities of the Trapezium stars."
That begs the question of the Trapezium's motions relative to the cloud itself and to each other.

For a 100-150 solar mass black hole to be lurking in the cloud, the Trapezium's neighborhood looks quite placid. Compare it to the Milky's Way's Arches near the center which are almost certainly hole-formed, and said to be ~4M in mass if a black hole. The Arches are a large-scale structure.

What would you expect the neighborhood to look like if a black hole was there? And what are the "Milky Way's Arches"?

These arches?

I don't know. What are those?

Chris Peterson wrote:

Ann wrote:

Chris Peterson wrote: What would you expect the neighborhood to look like if a black hole was there? And what are the "Milky Way's Arches"?

These arches?

I don't know. What are those?

They are the arches near the Arches Cluster. I think the Arches Cluster was named after them. I would guess the gaseous arches were caused either by powerful supernovas in their vicinity, or by outbursts of the supermassive central black hole of the Milky Way.

The bright object at right in the picture marks the position of the Milky Way central black hole.

Ann

Ann wrote:They are the arches near the Arches Cluster. I think the Arches Cluster was named after them. I would guess the gaseous arches were caused either by powerful supernovas in their vicinity, or by outbursts of the supermassive central black hole of the Milky Way.

Given that these structures are very young, I'd think supernovas are more likely. Of course, we don't know how long it's been since our galaxy's central black hole was active. In any case, I don't think we can draw any parallels between what's happening at the center of the galaxy and what a much smaller black hole might be doing in a small nebula like Orion, especially one in which most of the gas has dissipated.

Chris Peterson wrote: Given that these structures are very young, I'd think supernovas are more likely.

I agree. In my opinion, the arches don't seem to be centered on Sagittarius A*, but rather on the Quintuplet Cluster, just below the lowest arch. The Pistol Star, a member of the Quintuplet Cluster, is very obvious in the image I posted in my previous post.

The Quintuplet Cluster is old enough to have produced one or even a few supernovas, which might explain the arches that seem to be centered on this cluster. And if the Pistol Star is an LBV, which I think it is, this star alone might have contributed to at least one of the arches centered on it.

And really, the other arches seem really pretty much centered on the Arches Cluster itself! Who knows what the Arches Cluster has been up to?

Of course, we don't know how long it's been since our galaxy's central black hole was active. In any case, I don't think we can draw any parallels between what's happening at the center of the galaxy and what a much smaller black hole might be doing in a small nebula like Orion, especially one in which most of the gas has dissipated.

I have to admit that the idea that there might be a black hole in the Trapezium is too weird for me. That, of course, doesn't mean it can't be true.

Ann

Chris Peterson wrote:

douglas wrote:"The presence of a black hole within the cluster could explain the observed high velocities of the Trapezium stars."
That begs the question of the Trapezium's motions relative to the cloud itself and to each other.

For a 100-150 solar mass black hole to be lurking in the cloud, the Trapezium's neighborhood looks quite placid. Compare it to the Milky's Way's Arches near the center which are almost certainly hole-formed, and said to be ~4M in mass if a black hole. The Arches are a large-scale structure.

What would you expect the neighborhood to look like if a black hole was there? And what are the "Milky Way's Arches"?

https://apod.nasa.gov/apod/ap010614.html

They are more suggestive of magnetic fields than supernova bubbles, so at the scale of observation would you say they are unique to the galaxy's center?
Concentric sequential supernova bubbles? I can't go with that possibility

This is the picture I was thinking of: those radio arcs look to be magnetically confined. They are large scale, though.
Galactic Center Radio Arc:
X-ray Gas Associated With Galactic Center Radio Arc
http://chandra.harvard.edu/photo/2002/gradioarc/

I would say if a black hole was present there'd be evidence of gas flow being affected by it, stars with anomalous orbital behavior, an X-ray point source that would have visible components associated with it ..
Just the scenario of the Trapezium stars being possibly very young and the black hole that supposedly flung them to high velocities then hiding so easily afterwards seems unlikely.

Perhaps it's a personal conceit, but pictures of environs of suspected black holes usually have a "strained" aspect to gas orbital motion in their vicinities.
These 2 pictures, even though at great orbital distances from the galaxies' centers, show that "strained" nature. Disrupted, sure, but more than that, call it "gravitationally fated new orbital motion" whose fate is tied to (pardon the expression) the center's activity?
http://www.skyandtelescope.com/astronom ... -ngc-4696/

Chris Peterson wrote:

Ann wrote:They are the arches near the Arches Cluster. I think the Arches Cluster was named after them. I would guess the gaseous arches were caused either by powerful supernovas in their vicinity, or by outbursts of the supermassive central black hole of the Milky Way.

Given that these structures are very young, I'd think supernovas are more likely. Of course, we don't know how long it's been since our galaxy's central black hole was active. In any case, I don't think we can draw any parallels between what's happening at the center of the galaxy and what a much smaller black hole might be doing in a small nebula like Orion, especially one in which most of the gas has dissipated.

There is a contrast you can note and that is our galaxy's center is the focus of orbit. Orion is totally relaxed free form free fall with the only observable forces are stellar winds, supernova bubbles, and the pearls on a string of local star formations.

It all really comes back on this question to the Trapezium stars' relative motions to each other. If their "cluster" is moving as a unit then you know it wasn't inspired by a black hole.

douglas wrote:

Chris Peterson wrote:What would you expect the neighborhood to look like if a black hole was there? And what are the "Milky Way's Arches"?

They are more suggestive of magnetic fields than supernova bubbles, so at the scale of observation would you say they are unique to the galaxy's center?
Concentric sequential supernova bubbles? I can't go with that possibility

Well, I doubt there is any relation to magnetic fields. Interstellar magnetic fields, where they have been measured, are very weak and don't contribute to structure. We have many examples of supernova remnants that look like this, however.

I would say if a black hole was present there'd be evidence of gas flow being affected by it, stars with anomalous orbital behavior, an X-ray point source that would have visible components associated with it ..

Obviously there is no active black hole in Orion. So we're left with detecting it indirectly, which is difficult. However, the referenced work demonstrates that the production of a large black hole is feasible (or even necessary) given some assumptions about initial conditions, and that the motion of the Trapezium stars provides evidence for the existence of such a black hole. But more observation is required to detect one based on stellar motions.

douglas wrote:

Chris Peterson wrote:In any case, I don't think we can draw any parallels between what's happening at the center of the galaxy and what a much smaller black hole might be doing in a small nebula like Orion, especially one in which most of the gas has dissipated.

There is a contrast you can note and that is our galaxy's center is the focus of orbit. Orion is totally relaxed free form free fall with the only observable forces are stellar winds, supernova bubbles, and the pearls on a string of local star formations.

Even in the center of our galaxy, the visible effects of the central black hole are very small. Here we are talking about a black hole on the order of several million solar masses, which is significantly impacting the orbits of a dozen or so stars that are very close, and, just at the limits of our ability to measure them, the orbits of a few hundred other stars that are within just a parsec or so. That's an incredibly different situation than a 100 solar mass black hole in a much sparser, much less dense region like the Orion nebula.

It all really comes back on this question to the Trapezium stars' relative motions to each other. If their "cluster" is moving as a unit then you know it wasn't inspired by a black hole.

Why do you know that? We're talking about a cluster of stars that all lie within about a light year of each other. An intermediate mass black hole a few light years from the cluster would cause all of them to move very much in unison.

Chris Peterson wrote: We're talking about a cluster of stars that all lie within about a light year of each other. An intermediate mass black hole a few light years from the cluster would cause all of them to move very much in unison.

Do they?

Ann

Ann wrote:

Chris Peterson wrote: We're talking about a cluster of stars that all lie within about a light year of each other. An intermediate mass black hole a few light years from the cluster would cause all of them to move very much in unison.

Do they?

That was what I inferred from the article, that the cluster has a high proper motion and one explanation is an intermediate mass black hole.

As Ann said: "the arches don't seem to be centered on Sagittarius A*, but rather on the Quintuplet Cluster, just below the lowest arch. The Pistol Star, a member of the Quintuplet Cluster, is very obvious in the image I posted in my previous post.

The Quintuplet Cluster is old enough to have produced one or even a few supernovas, which might explain the arches that seem to be centered on this cluster. And if the Pistol Star is an LBV, which I think it is, this star alone might have contributed to at least one of the arches centered on it.

And really, the other arches seem really pretty much centered on the Arches Cluster itself!"

Would supernova bubbles remnants last that long in the center's environment if the Quintuplet Cluster is that old?

Galactic Center: https://apod.nasa.gov/apod/ap081211.html
Orbital animations: https://io9.gizmodo.com/the-video-that- ... 1114918644

Read this: " .. an X-ray flare revealed the presence of a pulsar within one light-year of the Milky Way's black hole. R.P. Eatough and colleagues measured the light from the pulsar and found it was strongly rotated, a sure sign of a magnetic field. If the magnetic field they detected extends to the surface of the black hole, it would be sufficient to explain the entire spectrum of emissions from the Milky Way's center."
https://arstechnica.com/science/2013/08 ... lack-hole/

In summation, though, the Orion Nebula would surely reveal the presence of an intermediate black hole.

Chris Peterson wrote:

Ann wrote:

Chris Peterson wrote: We're talking about a cluster of stars that all lie within about a light year of each other. An intermediate mass black hole a few light years from the cluster would cause all of them to move very much in unison.

Do they?

That was what I inferred from the article, that the cluster has a high proper motion and one explanation is an intermediate mass black hole.

Clusters are known to break up over time, each going their own ways.

If a high proper motion has been established it must be possible to interpolate its path. Influences deliver .. artifacts.

douglas wrote:

Chris Peterson wrote:

Ann wrote: Do they?

That was what I inferred from the article, that the cluster has a high proper motion and one explanation is an intermediate mass black hole.

Clusters are known to break up over time, each going their own ways.

It depends on whether the stars in the cluster are gravitationally bound, or whether they simply formed together fairly recently.

If a high proper motion has been established it must be possible to interpolate its path. Influences deliver .. artifacts.

I don't know just how closely the Trapezium has been studied, especially considering modern instruments with very high resolution.

Chris Peterson wrote:I don't know just how closely the Trapezium has been studied, especially considering modern instruments with very high resolution.

Perhaps Gaia will soon help reveal whether the Orion Nebula contains a BH by providing much better actual motions for the Tarpezium and neighboring stars. It was the movements of the stars surrounding the Milky Way's center that clinched the case for it containing a Supermassive BH.

Bruce

Guest wrote:

Chris Peterson wrote:
I don't know just how closely the Trapezium has been studied, especially considering modern instruments with very high resolution.

Perhaps Gaia will soon help reveal whether the Orion Nebula contains a BH by providing much better actual motions for the Tarpezium and neighboring stars. It was the movements of the stars surrounding the Milky Way's center that clinched the case for it containing a Supermassive BH.

• . http://www.skyandtelescope.com/observin ... s12062105/