Hubble Catches Some Cosmic Fireworks

Roland Piquepaille writes "On this Fourth of July, it's usual -- at least in the U.S. -- to watch fireworks. But I want to invite you to see very special ones, celestial fireworks discovered by the Hubble Space Telescope. Astronomy Magazine has the story. "In a newly released image, the Hubble Space Telescope peers into a neighboring galaxy to capture a gorgeous view of a supernova remnant called LMC N 49. Also known as DEM L 190, the nebula lies within the Large Magellanic Cloud approximately 160,000 light-years away." Read this summary for more details and a nice illustration from the Hubble Heritage Team. You can find additional tons of information at this Hubble Heritage Project page."

Comments

Re:here is another one

[shadowbearer]

Also photons and subatomic particles impacting on gas clouds around the star cause the glow (the impact transfers energy to the gas, heating it).

Sure makes for pretty pictures! :-) here's a page with some good animations on it.

SB

Astronomy Picture of the day

[Dixie_Flatline]

The APOD also has a good picture of this today.

7.2 Megapixel Fireworks

[Anonymous Coward]

If you visit APOD (Astronomy Picture Of the Day) they link to a huge 7.2 megapixel version of this picture. So, unless your desktop is bigger than 2700x2700 anyone can scale it down and make a cool desktop from this.

Sorry, but you're missing the point

[pq]

First of all, yes, I am an astronomer, and I have used the HST (only twice, but hey, I'm a radio astronomer...). A couple of misconceptions in your post:

• The colour portion of the pic is a composite from two or more pictures.
  True, but this is always true: in order not to saturate detectors, and to remove the inevitable cosmic rays, it is typical to take lots of dithered exposures. For an example of just how serious this cosmic ray problem is, take a look at this before and after image pair.
• The colours are so vibrant you have to assume they're retouched
  True, they are assigned, but it is very typical to get images in multiple filters, each of which has a well defined "color" - so it is easy to produce a final representative color image. Not even stretching the truth that much.
• the stars in the background were added
  Well, they retained the stars from one image (so they were not added), and rendered that in greyscale. Artistic license, definitely.
• many of the stars have lens flares ... Photoshopped in afterward
  Alas, flaring is typical: if you have bright stars in the field, the mirror obstructions (supports, secondary, etc) will produce flares. True at every optical telescope, from Palomar and Keck to the HST. Definitely not Photoshop!

The meat of your complaint seems to be this: Do we have to win tax-payer support by drawing Star Trek scenes and releasing them to news outlets as "science"? And that's a very valid question, even if, as I pointed out above, nothing really fishy is being done here.

My point of view, should that interest you, is this: except for a couple of very rare exceptions, every target the HST looks at is chosen after a brutal (trust me, brutal) review process. The HST costs an enormous of money to run, and they have lived up to that in terms of published peer-reviewed output per observation. So now if they kick in a few thousand extra bucks to take the science images, combine them with a little (not much, mind) artistic license, and release it to the public (who are, after all, paying for it) -- more power to them! Astronomy is one of those rare disciplines where the the excitement of cutting edge science can still be brought to the casual reader - if nothing else, as "Ooh, look, a pretty picture!" I think that is well worth it, as long as they aren't being scientifically dishonest.

(And that last point is a whole other story: do press releases over-hype the discovery? Does Nature twist a simple research result into "Unprecedented discovery revolutionizes our understanding of the Universe"? Maybe, but that's not a problem with the pretty pictures.)

Re:What's with all these doctored photos?!?

[mph]

While some of your criticisms have merit (such as superimposing the image on a separate starfield), some are off base.

The image is created through "observations" from Hubble, the important part being the fact that they use plural form. So the colour portion of the pic is a composite from two or more pictures. The colours are so vibrant you have to assume they're retouched,

No professional telescope uses color detectors. They use monochromatic CCDs behind various filters. These filters are chosen for scientific purposes and are not designed with human color response in mind. They may even be narrowband filters that only pass a single emission line, e.g. from hydrogen. Thus, any color image you see from a professional observatory will be combined from multiple exposures, and will be subject to artistic interpretation. Trying to mimic "what it would really look like" is, to a great extent, a lost cause; most things you look at through a telescope appear pretty washed out, but part of that is that the image is faint, and we're using our color-insensitive rods to see. And the filter set used may not be amenable to recreating human visual response. And the interesting detail may be in the infrared, or the near ultraviolet, which we cannot see. Or the detail may be in emission lines; where the emission from hydrogen is vs. the emission from oxygen.

People need to understand that HST isn't a big Canon digital camera. There is a lot of work involved in "reducing" astronomical data into a usable form, whether for science or PR. It makes no sense to use terms like "retouched." Raw data, as read out directly from the camera, is pretty much useless for any purpose. If I have an imaging run of a couple of nights at Palomar, for example, it generally takes at least two weeks (of long days) to get that data into a scientifically useful shape, at which point we use it to select objects for further spectroscopic study. After obtaining spectra, it takes more weeks to get the spectra into useful shape. Then we can start the long process of measuring scientifically useful things and learn something.

In addition many of the stars have lens flares which would destroy any scientific value they had which means the lens flares were Photoshopped in afterward!

I think you're referring to the cross-shaped diffraction spikes around stars, not lens flares. These are real. They are caused by the diffraction of light from the stars by the cross-shaped secondary mirror supports.

Don't worry about "destroying any scientific value." Telescope time is precious, whether on HST or any top observatory on the ground. You get diffraction spikes around bright objects (at least "bright" by the standards of the telescope). There's no way that the bright, spikey stars were the scientific target of that image. There's no way you would waste telescope time by exposing so long that your science object saturates or is surrounded by big diffraction spikes.

Re:this is too much...

[Walabio]

And the remnant of the supernova is outside of the galaxy in the Large Magellanic Cloud.