Starship Asterisk*

Messier 43

Explanation: Often imaged but rarely mentioned, Messier 43 is a large star forming region in its own right. It's just part of the star forming complex of gas and dust that includes the larger, more famous neighboring Messier 42, the Great Orion Nebula. In fact, the Great Orion Nebula itself lies off the lower edge of this scene. The close-up of Messier 43 was made while testing the capabilities of a near-infrared instrument with one of the twin 6.5 meter Magellan telescopes at Las Campanas Observatory in the Chilean Andes. The composite image shifts the otherwise invisible infrared wavelengths to blue, green, and red colors. Peering into caverns of interstellar dust hidden from visible light, the near-infrared view can also be used to study cool, brown dwarf stars in the complex region. Along with its celebrity neighbor, Messier 43 lies about 1,500 light-years away, at the edge of Orion's giant molecular cloud. At that distance, this field of view spans about 5 light-years.

<< Previous APOD

This Day in APOD

Next APOD >>

[/b]

Why does this image have stars showing two sets of diffraction spikes, offset about 15 degrees?

Texas Tea wrote:Why does this image have stars showing two sets of diffraction spikes, offset about 15 degrees?

One observation was probably taken at a slightly different orientation. Could have been more than one telescope in use.

This is a very nice and interesting infrared image. It's beautiful, too. I rarely find infrared images beautiful, because their mapped colors are usually so sharp and glaring, with their colors so sharply separated, like a child's painting. But today's image is not like that at all. The colors blend smoothly, displaying a rich palette.

The picture is very interesting, too. I assume that the bright star seen in the image is NU Orionis, the ionizing star of M43. It isn't obvious that a hot bright star will show up prominently in an infrared image. Of course, NU Orionis is a reddened star, with a positive B-V index, even though it is classified as an O9-type star. The reddening means that much of the energy it produces has been lost to us, and the light that reaches our eyes should be proportionally more infrared than if the star had been unreddened. But the way I understand it, the reddening shouldn't add any infrared light that wouldn't be there in an unreddened image. Perhaps I'm wrong about that.

I find it interesting that NU Orionis looks so much brighter than all the other stars in this image, even though all the other stars here are almost certainly cooler and therefore proportionally redder and more infrared than NU Orionis. This clearly proves that NU Orionis is the only really bright and massive star in M43. All the other stars here, certainly all the other stars in the "blue cavity", must be relatively small and cool. This configuration, with one bright star surrounded by many much smaller stars, reminds me of the Tau Canis Majoris cluster, NGC 2362.

Speaking of the "blue cavity", I must say that the rim of it looks positively fascinating. There is splendid detail here!

There is star formation going on all along the "lower edge" of the dusty ridge in the lower part of the image. The most interesting site of star formation is the red and yellow-colored region at lower right. It could possibly be the birthplace of stars more massive than the Sun, but this is not certain.

This is a beautiful and interesting picture.

Ann

Ann wrote:The picture is very interesting, too. I assume that the bright star seen in the image is NU Orionis, the ionizing star of M43.

As an aside, it's worth noting that NU Orionis is not the same star as Nu Orionis. "NU" is a catalog designation. "Nu" is the Greek letter. A nice opportunity for confusion for anybody looking up information on either of these objects. NU Orionis is in M43; Nu Orionis lies elsewhere in Orion.

It's nice to see an infrared image on APOD after what seems like a long time. I particularly like the infrared outflows and Herbig Haro objects visible to the left, these can also be seen optically but they are much more apparent in infrared.

Chris Peterson wrote:

Ann wrote:The picture is very interesting, too. I assume that the bright star seen in the image is NU Orionis, the ionizing star of M43.

As an aside, it's worth noting that NU Orionis is not the same star as Nu Orionis. "NU" is a catalog designation. "Nu" is the Greek letter. A nice opportunity for confusion for anybody looking up information on either of these objects. NU Orionis is in M43; Nu Orionis lies elsewhere in Orion.

Nu Orionis is another blue B-type star in Orion. It is hot, but not hot enough to ionize an emission nebula. Located well north of Betelgeuse, not all that far from Alhena at the feet of Gemini, Nu Oironis is the 24th brightest star in Orion.

Ann

What is the complex on lower right (~1/4 of image width from right and from bottom). one item includes apparent shadows cast downward (4-7 o'clock) and upward (11-1 o'clock) from a central object with yellow flare (from 1 to 2 o'clock). The yellow flare bends tot the right of the image turning redder as it goes. Below and to the right of this is a group of 3 overlapping rings/partial rings. Is all this one related complex? Does the complex have a name?

tmccants wrote:What is the complex on lower right (~1/4 of image width from right and from bottom). one item includes apparent shadows cast downward (4-7 o'clock) and upward (11-1 o'clock) from a central object with yellow flare (from 1 to 2 o'clock). The yellow flare bends tot the right of the image turning redder as it goes. Below and to the right of this is a group of 3 overlapping rings/partial rings. Is all this one related complex? Does the complex have a name?

I doubt it has any name. It's just structure in the nebula.

Chris Peterson wrote:

tmccants wrote:What is the complex on lower right (~1/4 of image width from right and from bottom). one item includes apparent shadows cast downward (4-7 o'clock) and upward (11-1 o'clock) from a central object with yellow flare (from 1 to 2 o'clock). The yellow flare bends tot the right of the image turning redder as it goes. Below and to the right of this is a group of 3 overlapping rings/partial rings. Is all this one related complex? Does the complex have a name?

I doubt it has any name. It's just structure in the nebula.

It probably has a HH number, or more likely multiple HH numbers although technically they would refer to the optical counterpart. These objects might be in the catalogue of molecular hydrogen objects.

starsurfer wrote:

Chris Peterson wrote:

tmccants wrote:What is the complex on lower right (~1/4 of image width from right and from bottom). one item includes apparent shadows cast downward (4-7 o'clock) and upward (11-1 o'clock) from a central object with yellow flare (from 1 to 2 o'clock). The yellow flare bends tot the right of the image turning redder as it goes. Below and to the right of this is a group of 3 overlapping rings/partial rings. Is all this one related complex? Does the complex have a name?

I doubt it has any name. It's just structure in the nebula.

It probably has a HH number, or more likely multiple HH numbers although technically they would refer to the optical counterpart. These objects might be in the catalogue of molecular hydrogen objects.

Oh, they have names! You can't live around the Orion Complex, be seen by a ground-based telescope, and get away with not having a name. The red area in general is called OMC 2 (Orion Molecular Complex 2) and the shadow-casting, light-cone making object itself has a lot of catalog identifiers and is a YSO (Young Stellar Object). That associated HH object listed at the SIMBAD entry is at the far right of the image. I wonder if it really is associated with the YSO in question. It's hard to tell. Here's a picture with all the HH objects circled. Just a quick thing, didn't have time to label them too.

Thank you for the image with HH regions circled.
The second circled HH region from the right appears to my untrained eye to have a sequence of 3 rings above it. Looks something like a series of shocks surrounding a jet emanating from the HH region at an angle but towards our line of sight. Probably wrong but regardless, plenty of action in that neighborhood..

Good afternoon. I am extremely curious as to the portion of the picture in the bottom right. There is definitely activity in this area and it appears there is a a large amount of light reflcting of the clouds. Has this area been studied in detail?

FANTASMOGORICAL. Thanks again APOD.