APOD: NGC 6357: The Lobster Nebula (2022 Nov 01)

[APOD Robot]

NGC 6357: The Lobster Nebula

Explanation: Why is the Lobster Nebula forming some of the most massive stars known? No one is yet sure. Cataloged as NGC 6357, the Lobster Nebula houses the open star cluster Pismis 24 near its center -- a home to unusually bright and massive stars. The overall red glow near the inner star forming region results from the emission of ionized hydrogen gas. The surrounding nebula, featured here, holds a complex tapestry of gas, dark dust, stars still forming, and newly born stars. The intricate patterns are caused by complex interactions between interstellar winds, radiation pressures, magnetic fields, and gravity. The image was taken with DOE's Dark Energy Camera on the 4-meter Blanco Telescope at the Cerro Tololo Inter-American Observatory in Chile. NGC 6357 spans about 400 light years and lies about 8,000 light years away toward the constellation of the Scorpion.

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[beryllium732]

Where is the star located exactly relative to the image? It doesn't resemble the picture from two years ago

https://apod.nasa.gov/apod/ap200830.html

[Ann]

Where is the star located exactly relative to the image? It doesn't resemble the picture from two years ago

https://apod.nasa.gov/apod/ap200830.html

The star cluster in NGC 6357 is "upside down" compared to a previous APOD. Or maybe it is the previous APOD that is upside down.

A Hubble Space Telescope (HST) image of Pismis 24-1, the 'core' of NGC 6357. Image credit: NASA, ESA and Jesœs Maz Apellÿniz (Instituto de astrofsica de Andaluca, Spain). Acknowledgement: Davide De Martin

---

Ann

[Ann]

APOD Robot wrote:

NGC 6357 spans about 400 light years and lies about 8,000 light years away toward the constellation of the Scorpion.

Wikipedia wrote about NGC 6357:

It is located about ~5,500 light years away from Earth.

ESA's Gaia satellite has measured a parallax of 0.4923 ±0.0286 milliarcseconds for the bright Pismis 24 star HD 157504, as reported by Simbad Astronomical Database. This corresponds to a distance of ~6,600 light-years.

Take your pick as to how far away NGC 6357 is.

Ann

[orin stepanek]

Dark Energy Camera!
If we can't see dark energy; how can we take pictures of it???

I didn't make this mess! I was framed~

[Chris Peterson]

model-decam.jpg
Dark Energy Camera!
If we can't see dark energy; how cac we take pictures of it???

What does "see" mean? Almost everything we think we know about the Universe is from stuff that we can't really see. We can't see hydrogen, all we get is photons that have a certain energy and from which we infer the presence of that element... never measured or detected directly. Astronomy is the science of indirect detection. Other than a few bits of matter from our own solar system, pretty much everything is photons and energetic particles, and what we can conclude from measuring them. We "see" hydrogen by making assumptions about radio waves and red light. We "see" dark matter by measuring Doppler shifts to derive the motion of material, and make inferences about the gravitational fields that produce such motion. We "see" dark energy by measuring cosmological redshifts and making inferences about the relationships between distance and expansion rates, and conclude something about the forces or properties that drive them.

This camera was constructed for a project that surveyed millions of distant galaxies to add to the database of information used to clarify theory regarding dark energy. Hence, its name.

[HellCat]

The star cluster in NGC 6357 is "upside down" compared to a previous APOD. Or maybe it is the previous APOD that is upside down.
Ann

I prefer to think that we are the ones who are upside down. The universe knows what it's doing.
Steve

PS - Oh yes! I logged in to find out why the stars in the bottom of the image are "fuzzy." I'm assuming a digital artifact?

[Chris Peterson]

The star cluster in NGC 6357 is "upside down" compared to a previous APOD. Or maybe it is the previous APOD that is upside down. :wink:
Ann

I prefer to think that we are the ones who are upside down. The universe knows what it's doing.
Steve

PS - Oh yes! I logged in to find out why the stars in the bottom of the image are "fuzzy." I'm assuming a digital artifact?

What stars are "fuzzy"? All the stars in the image look the same to me.

[orin stepanek]

model-decam.jpg
Dark Energy Camera!
If we can't see dark energy; how cac we take pictures of it???

What does "see" mean? Almost everything we think we know about the Universe is from stuff that we can't really see. We can't see hydrogen, all we get is photons that have a certain energy and from which we infer the presence of that element... never measured or detected directly. Astronomy is the science of indirect detection. Other than a few bits of matter from our own solar system, pretty much everything is photons and energetic particles, and what we can conclude from measuring them. We "see" hydrogen by making assumptions about radio waves and red light. We "see" dark matter by measuring Doppler shifts to derive the motion of material, and make inferences about the gravitational fields that produce such motion. We "see" dark energy by measuring cosmological redshifts and making inferences about the relationships between distance and expansion rates, and conclude something about the forces or properties that drive them.

This camera was constructed for a project that surveyed millions of distant galaxies to add to the database of information used to clarify theory regarding dark energy. Hence, its name.

Wow! Thanks for the explanation Chris! Never too old to learn!

[johnnydeep]

Where is the star located exactly relative to the image? It doesn't resemble the picture from two years ago

https://apod.nasa.gov/apod/ap200830.html

APOD 1 November 2022 annotated.png

APOD 1 November 2022 detail.png

The star cluster in NGC 6357 is "upside down" compared to a previous APOD. Or maybe it is the previous APOD that is upside down.

A Hubble Space Telescope (HST) image of Pismis 24-1, the 'core' of NGC 6357. Image credit: NASA, ESA and Jesœs Maz Apellÿniz (Instituto de astrofsica de Andaluca, Spain). Acknowledgement: Davide De Martin

---

Ann

So how do the two fit? I'm still not seeing any resemblance or commonality at all:

[HellCat]

The star cluster in NGC 6357 is "upside down" compared to a previous APOD. Or maybe it is the previous APOD that is upside down.
Ann

I prefer to think that we are the ones who are upside down. The universe knows what it's doing.
Steve

PS - Oh yes! I logged in to find out why the stars in the bottom of the image are "fuzzy." I'm assuming a digital artifact?

What stars are "fuzzy"? All the stars in the image look the same to me.

Hi Chris. Poor wording on my part. Several of the stars in the lower center of the image appear over exposed.
I've annotated the image to show these. Unless they are all diffuse galaxies, I don't think I've seen stars like this.
Steve

[Ann]

Where is the star located exactly relative to the image? It doesn't resemble the picture from two years ago

https://apod.nasa.gov/apod/ap200830.html

APOD 1 November 2022 annotated.png

APOD 1 November 2022 detail.png

The star cluster in NGC 6357 is "upside down" compared to a previous APOD. Or maybe it is the previous APOD that is upside down.

Ann

So how do the two fit? I'm still not seeing any resemblance or commonality at all:


ngc 6357.JPG

Take a look at these two pictures:

---

As you can see in the annotated detail of the APOD, the bright nebula is "above" the line of bright stars. In the other picture, the bright nebula is "below" the line of bright stars.

Ann

[Chris Peterson]

So how do the two fit? I'm still not seeing any resemblance or commonality at all:

That's because they are at very different scales. Today's APOD is a few degrees across. The HST image is a few arcminutes across.
_

[Chris Peterson]

Lobster_Blanco_960_some_stars_circled.jpg

I prefer to think that we are the ones who are upside down. The universe knows what it's doing.
Steve

PS - Oh yes! I logged in to find out why the stars in the bottom of the image are "fuzzy." I'm assuming a digital artifact?

What stars are "fuzzy"? All the stars in the image look the same to me.

Hi Chris. Poor wording on my part. Several of the stars in the lower center of the image appear over exposed.
I've annotated the image to show these. Unless they are all diffuse galaxies, I don't think I've seen stars like this.
Steve

Ah. Just scattered light around the bright stars. It's pretty common in astronomical images with bright stars in them. (Most of the scatter is probably in the optics, although some may be atmospheric, as well.)

[johnnydeep]

So how do the two fit? I'm still not seeing any resemblance or commonality at all:

That's because they are at very different scales. Today's APOD is a few degrees across. The HST image is a few arcminutes across.
_
Lobster_Blanco_4000+HST.jpg

Thanks. Yeah, I figured it out from Ann's reply just before I saw your post. Here's my side-by-side partially overlayed view:

[Cosmic ducks in a row]

I find the near-perfect alignment of those four big stars just provocative. The odds that it's just random? It's one thing to be in a birth cluster; here they look like they've been shot out of a pipe.

[Chris Peterson]

I find the near-perfect alignment of those four big stars just provocative. The odds that it's just random? It's one thing to be in a birth cluster; here they look like they've been shot out of a pipe.

You will find similar cases in almost any astronomical image that is rich in stars. Our brains are desperate to read meaning into patterns, even when there is none.