In the sail of Argo
Sunday, September 30. 2007
Spitzer Space Telescope (2007)
The constallation Vela takes its name from the “sail” of Argo, the mythical ship on which Jason and the Argonauts sailed to retrieve the Golden fleece. The constellation hosts a vast complex of clouds where new stars are being born. This is not the only place in our Galaxy where stars are currently formed (the Orion nebula being perhaps the most famous one), but it is special to us because it is at a larger distance from the center of the Galaxy, than the Sun is. As such, it allows us to study the processes of star formation in the periphery of our “island universe”.
The image shows some of the star forming clouds in Vela. This is just a detail of a much larger map I made using data I took this year with the Spitzer Space Telescope. The color in the image are not the same a human eye would see. Spitzer is an infrared telescope, and as such it records light which our eyes are not sensitive to. It is a bit like a digital infrared film, except that the radiation that Spitzer records is more extreme than the one of a regular infrared film. If I had to be faithful to the color scheme of the human vision, the picure would have appeared completely black. I chose instead to associate the red, green and blue components of the image to three different infrared colors: blue to the colors typical of the stars and shocked gas, green to the color of small dust grains, and red to the color of cold dust. In this way, the image helps to understand the different components of this cosmic vista. For example, the red dots in the image indicate the presence of very young stars still embedded in their dusty cocoon. The gree arabesques trace the distribution of hot dust where star formation is enhanced. The blue dots shows the distribution of older stars.
If you are so inclined you can read the paper I wrote with my italian collaborators, based on the analysis of just the “red” component of this image: astro-ph/07909.1060. We are now working in trying to understand the whole picture using all the components of these image.
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Looks like underwater photographs, deep deep below the surface where you (....or more presicely I) would never believe there could be anything colorfull...
You say the colors are not visible to the human eye, does that mean that there are no colors, or are the colors just not visible because of the great distance, or because our eyes are adjusted differently ?
Is there a simillarity between colors in deep sea fish and plants, and colors in outer space ? You know these see-through, blind ones.
(Excuse my bad English, Massimo. I cant find the right words again...)
BTW: FANTASTIC photograph! Perhaps you could mount a Holga to that lens
THAT would be different!
You say the colors are not visible to the human eye, does that mean that there are no colors, or are the colors just not visible because of the great distance, or because our eyes are adjusted differently ?
Is there a simillarity between colors in deep sea fish and plants, and colors in outer space ? You know these see-through, blind ones.
(Excuse my bad English, Massimo. I cant find the right words again...)
BTW: FANTASTIC photograph! Perhaps you could mount a Holga to that lens
THAT would be different!
Eh, lots of questions... Let’s see...
There are actually colors in space, even in the range that the human eye can see. Stars have different colors: the Sun for example has a yellowish color while Vega or Sirius are blue. Other stars like Belegeuse are instead red. Nebulae like the Orion Nebula for example have a green tint. All these colors you can see with the naked eye, even though (with the exception of the Sun) they appear washed out because the color receptors of the human retina (the cones) are not very sensitive to faint lights: the photoreceptors for dim lights (the rods) are not sensitive to colors. So when we look at the celestial objects with the naked eye we don’t see many colors, even though they are there, because our eyes are not much sensitive to them in faint light conditions.
If you look through a telescope, even without using a camera attached at the ocular, these colors become more apparent. So analogy with the deep sea doesn’t work because in the case of deep sea, unless you bring your own flashlight, the light you have is mostly blue to start with; in space the celestial objects glow of all colors, but they are too faint to generally appreciate it.
The case of the photograph above, however, is still different. I did the observations with an infrared telescope and camera, which is sensitive to light that the human retina cannot catch (neither the cones or the rods). The camera selects this infrared light by using filters that trow away all the other “colors” and keep only the infrared. The detector of the camera is sensitive to this infrared light, which allows it to form the image. This is the same technique used when doing infrared photography with a regular camera: one uses an infrared film as “detector”, and an infrared filter to reject the visible light that would otherwise contaminate the picture. If I were to look though these infrared filters I would not see anything, because the light that they let pass through cannot be seen by my eyes: hence the image would appear black to me (and this is what I meant above). But if I have the right detector I can still reconstruct an image, the same way the infrared film does it (but I need to use an artificial color map to render this image in a visible way).
One last comment: it is true that we cannot see the type of infrared light represented in the image above but we can feel it! Spitzer is built to record the so-called “thermal infrared” which is the part of the electromagnetic spectrum associated to the radiant heat: if your hands were sensitive enough you could feel the “heat” coming from these celestial sources and draw an image like the one I posted
There are actually colors in space, even in the range that the human eye can see. Stars have different colors: the Sun for example has a yellowish color while Vega or Sirius are blue. Other stars like Belegeuse are instead red. Nebulae like the Orion Nebula for example have a green tint. All these colors you can see with the naked eye, even though (with the exception of the Sun) they appear washed out because the color receptors of the human retina (the cones) are not very sensitive to faint lights: the photoreceptors for dim lights (the rods) are not sensitive to colors. So when we look at the celestial objects with the naked eye we don’t see many colors, even though they are there, because our eyes are not much sensitive to them in faint light conditions.
If you look through a telescope, even without using a camera attached at the ocular, these colors become more apparent. So analogy with the deep sea doesn’t work because in the case of deep sea, unless you bring your own flashlight, the light you have is mostly blue to start with; in space the celestial objects glow of all colors, but they are too faint to generally appreciate it.
The case of the photograph above, however, is still different. I did the observations with an infrared telescope and camera, which is sensitive to light that the human retina cannot catch (neither the cones or the rods). The camera selects this infrared light by using filters that trow away all the other “colors” and keep only the infrared. The detector of the camera is sensitive to this infrared light, which allows it to form the image. This is the same technique used when doing infrared photography with a regular camera: one uses an infrared film as “detector”, and an infrared filter to reject the visible light that would otherwise contaminate the picture. If I were to look though these infrared filters I would not see anything, because the light that they let pass through cannot be seen by my eyes: hence the image would appear black to me (and this is what I meant above). But if I have the right detector I can still reconstruct an image, the same way the infrared film does it (but I need to use an artificial color map to render this image in a visible way).
One last comment: it is true that we cannot see the type of infrared light represented in the image above but we can feel it! Spitzer is built to record the so-called “thermal infrared” which is the part of the electromagnetic spectrum associated to the radiant heat: if your hands were sensitive enough you could feel the “heat” coming from these celestial sources and draw an image like the one I posted
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