Starship Asterisk*

An amazing image!
The SkyFactory web site has a handy intereactive image viewer.
http://www.skyfactory.org/vela/vela_int.htm


My question is, if Vela SNR is in the middle of the image what is that almost perfectly blue coloured circle in the top left of the image as displayed on Apod and on the top right of the image on the SkyFactory web page?
You can mouseover this image for the labeling or annotated version.
http://www.skyfactory.org/vela/vela.htm

Hi,

that is nothing of astronomical-related. It is just a reflection generated by a bright star that is out of the field of view.
Unfortunatelly, removing that kind of artifact is not an easy task, because of its size in the full-res version.

Cheers,
Davide

I'm a novice at astronomy, so forgive me if the answer to this question is obvious.

In today's APOD (2/13/2007), the description of the nebula included the comment that is appears as 20x the diameter of the full moon.

How can this be? Wouldn't a photograph of a faint structure that encompasses that large an area of the sky be completely washed out by the multitudes of stars that are brighter than the structure? How do astronomers measure the diameter of something that large but faint?

Thanks

aweisberg wrote:I'm a novice at astronomy, so forgive me if the answer to this question is obvious.

In today's APOD (2/13/2007), the description of the nebula included the comment that is appears as 20x the diameter of the full moon.

How can this be? Wouldn't a photograph of a faint structure that encompasses that large an area of the sky be completely washed out by the multitudes of stars that are brighter than the structure? How do astronomers measure the diameter of something that large but faint?

Thanks

Hi aweisberg,

There's already a thread about this APOD, you should really have posted your question on that thread.

These images are achieved sometimes with millions of seconds of exposure to gather enough light detail for such a fine resolution picture.
(11.57 days for a one million second exposure)
You simply would have no way to see something like this with binoculars or a small telescope, much less the naked eye.
They are still there though, and if you can see it, you can measure it.

Welcome aweisberg,

One of the links in the description,
http://www.skyfactory.org/vela/vela.htm
gives a bit more info about the size of the image. More specifically, it's stated that the image is 19 times the size of the full moon, which is a minor difference, I know. Scrolling down a bit on that page shows a sky map of the area, as well as a roll over image. Very interesting.
Anyway, (lost the train of thought - sorry!) tons of good info on that link. (The other links are good too, but that one seemed the most informative to me.)

Happy sky watching!

A gigapixel! Wow, now THAT's a mosaic. Well done, Davide!

How does Photoshop handle images that large? Do you have a 64 bit system with tens of gigabytes? Or did you edit in some other app? Just curious.

Wouldn't a photograph of a faint structure that encompasses that large an area of the sky be completely washed out by the multitudes of stars that are brighter than the structure?

That's actually a pretty good question. The trick is to have optics so clean and so free of diffraction and aberrations that stars stay focused on just a tiny area and don't adversely affect the parts of the image away from those bright stars. As you can see, the brighter ones do wash out a small area.

-Noel

Hi Noel,

thanks!
Well no, I just have a common PC (Pentium 4 at 3.2 GHz), with 4 gigs of RAM and plenty of space on hard disks.
Of course, a good amount of patient is required! The whole processing took some months of my free time. Layered raw file is over 16 gigabytes and it takes nearly half an hour just to open or save. Flatted uncompressed file is just under 3 gigabytes, so quite easy to handle.

Cheers,
Davide

Thank you to everyone that responded to my original posting. The video of the nebula is simply amazing as is the rest of the web page.

Even with the explanation in hand, I'm still amazed at the ability to image the nebula across such a large swath of the sky.

Thanks again!

ddemartin wrote:Hi Noel,

thanks!
Well no, I just have a common PC (Pentium 4 at 3.2 GHz), with 4 gigs of RAM and plenty of space on hard disks.
Of course, a good amount of patient is required! The whole processing took some months of my free time. Layered raw file is over 16 gigabytes and it takes nearly half an hour just to open or save. Flatted uncompressed file is just under 3 gigabytes, so quite easy to handle.

Cheers,
Davide

So you're responsible for bringing us this APOD? Right on. If you don't mind my asking, do you do this on your own, as part of the Hubble Heritage Project, or for work?

Hello All

The image shows lots of nova and supernova and new star formation.

Nice image

iamlucky13 wrote: So you're responsible for bringing us this APOD? Right on. If you don't mind my asking, do you do this on your own, as part of the Hubble Heritage Project, or for work?

No, I don't do this for work, nor as part of a Hubble work.
Basically, I do this for my own pleasure, for curiosity, for interest in and love of astronomy. To admire the awesome beauty of the Universe and, of course, to allow other to see it. To inspire myself and, hopefully, other sensible minds.
Cheers,
Davide

Scientists say we're made up, at least in part, of second-hand star material. That's how we explain all the heavy elements.

Seeing the immense scale of Davide's image, it' s less difficult to imagine the filaments of a supernova remnant coalescing into new solar systems.

-Noel

Hello All

It is true that we go through phases in the evolution of star.

I would not think of it as second hand.

Within the star envelope, The elements from H to Fe and Ni are formed from mainly fusion and some fission reaction.

As for the heavier elements they do form but are unsatble until the star goes supernova. During the supernova stage the environment changes and the heavier elements are formed.

You can google for the info its general info.