APOD: Trapezium: At the Heart of Orion (2018 Aug 05)

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APOD Robot
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APOD: Trapezium: At the Heart of Orion (2018 Aug 05)

Post by APOD Robot » Sun Aug 05, 2018 4:05 am

Image Trapezium: 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. 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 recent 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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Boomer12k
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Re: APOD: Trapezium: At the Heart of Orion (2018 Aug 05)

Post by Boomer12k » Sun Aug 05, 2018 9:17 am

Outstanding detail, I just love it... about the same angle I get, but with tons more detail...

Mine are 6", 8", and 10" telescopes respectfully, with the same camera...

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heehaw

Re: APOD: Trapezium: At the Heart of Orion (2018 Aug 05)

Post by heehaw » Sun Aug 05, 2018 9:23 am

Those are nice, Boomer!

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Re: APOD: Trapezium: At the Heart of Orion (2018 Aug 05)

Post by Boomer12k » Sun Aug 05, 2018 10:46 am

heehaw wrote:
Sun Aug 05, 2018 9:23 am
Those are nice, Boomer!
Thanks....
In the upper left quarter... a Porpoise...the bottle nose, the eye, and even a blow hole....my pareidolia kicking in...even looking at the small image on the forum page, it looks like a Porpoise jumping, or something...

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Re: APOD: Trapezium: At the Heart of Orion (2018 Aug 05)

Post by De58te » Sun Aug 05, 2018 11:25 am

I see in the upper left the head and fore legs of the Lion King leaping out of the cloud. The snout is snarling but the eyes are missing. (or the eyes could be covered by the fur of his mane). Top of his head is also a bit flattened or he has his ears laid back.

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Re: APOD: Trapezium: At the Heart of Orion (2018 Aug 05)

Post by Arioch » Sun Aug 05, 2018 4:30 pm

If there is such a black hole in the cluster, shouldn't it (or at least its lensing effect) be easily observed against such a bright background?

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Re: APOD: Trapezium: At the Heart of Orion (2018 Aug 05)

Post by MarkBour » Sun Aug 05, 2018 9:42 pm

Arioch wrote:
Sun Aug 05, 2018 4:30 pm
If there is such a black hole in the cluster, shouldn't it (or at least its lensing effect) be easily observed against such a bright background?
Good question, I'm hoping to see the answer by someone far more qualified than me.
But I can mention these thoughts:
  1. For direct observation, it would be pretty small and they're famous for *not* emitting that much evidence when not accreting. I think its Schwarzchild radius would be about 300 km?
  2. Its lensing effect would also probably not be very great, viewed at this distance, for the same reason as in (1). Also, it probably would not be in front of everything else, it probably has lots of masking from us by the material in the nebula.
Mark Goldfain

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Re: APOD: Trapezium: At the Heart of Orion (2018 Aug 05)

Post by Chris Peterson » Sun Aug 05, 2018 10:22 pm

Arioch wrote:
Sun Aug 05, 2018 4:30 pm
If there is such a black hole in the cluster, shouldn't it (or at least its lensing effect) be easily observed against such a bright background?
When we see lensing, it comes from the dark matter around galaxies and galaxy clusters, not black holes (and even less, stellar mass black holes). The lensing would be so weak that it would only be detected by a near transit of a background star by the black hole- an event that would be very rare and require long periods of dedicated observation with high resolution telescopic systems.

Looking at the dynamics of the surrounding stars is a much easier and more reliable approach to identifying another massive body in the region.
Chris

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Re: APOD: Trapezium: At the Heart of Orion (2018 Aug 05)

Post by BDanielMayfield » Mon Aug 06, 2018 1:57 am

MarkBour wrote:
Sun Aug 05, 2018 9:42 pm
Arioch wrote:
Sun Aug 05, 2018 4:30 pm
If there is such a black hole in the cluster, shouldn't it (or at least its lensing effect) be easily observed against such a bright background?
Good question, I'm hoping to see the answer by someone far more qualified than me.
But I can mention these thoughts:
  1. For direct observation, it would be pretty small and they're famous for *not* emitting that much evidence when not accreting. I think its Schwarzchild radius would be about 300 km?
  2. Its lensing effect would also probably not be very great, viewed at this distance, for the same reason as in (1). Also, it probably would not be in front of everything else, it probably has lots of masking from us by the material in the nebula.
I'm not claiming to be any more qualified than Mark, but I can confirm that a 100 Sun black hole would only have a radius of 297 km, so only about 594 km across. Too tiny by far to be observed.

Mark's reasoning is sound. It would most likely be at the very center of the Trapezium, I would think.

Will GAIA be able to tell us the actual motions of the stars in the Trapezium cluster?

Bruce
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Re: APOD: Trapezium: At the Heart of Orion (2018 Aug 05)

Post by alter-ego » Mon Aug 06, 2018 3:56 am

BDanielMayfield wrote:
Mon Aug 06, 2018 1:57 am
...
Will GAIA be able to tell us the actual motions of the stars in the Trapezium cluster?
I believe so. The 3D stellar motion is composed of proper motion and radial velocity measurements which GAIA does well. The proper motion component ~ 0.07mas/yr → 0.2km/sec for stars <15th mag, and at 1500 ly. Radial velocity uncertainty ~0.3km/sec for stars < 8th mag. These uncertainties should be small enough to provide useful velocity data for the cluster.
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Re: APOD: Trapezium: At the Heart of Orion (2018 Aug 05)

Post by BDanielMayfield » Mon Aug 06, 2018 2:11 pm

alter-ego wrote:
Mon Aug 06, 2018 3:56 am
BDanielMayfield wrote:
Mon Aug 06, 2018 1:57 am
...
Will GAIA be able to tell us the actual motions of the stars in the Trapezium cluster?
I believe so. The 3D stellar motion is composed of proper motion and radial velocity measurements which GAIA does well. The proper motion component ~ 0.07mas/yr → 0.2km/sec for stars <15th mag, and at 1500 ly. Radial velocity uncertainty ~0.3km/sec for stars < 8th mag. These uncertainties should be small enough to provide useful velocity data for the cluster.
Excellent, as the Orion nebula is I think the closest major star forming region, and pinning down its true distance will reduce much uncertainty about the early formation of planetary systems, etc., and might provide the evidence needed to sinch up the black hole in Orion question.

Bruce
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