You may have noticed that I have ‘fallen off the internet’ this week, as a friend of mine recently said in a text message. Well the reason is that I have been attending a meeting about star formation and the Spitzer Space Telescope.

I am part of the Gould Belt Survey team working with Spitzer legacy data. Currently I am sat in a meeting but I thought I would post an entry explaining my absence from the web, which will actually continue for the next couple of weeks.

I may still posts the odd cool Digg story and the Abram’s Skynotes will continue. In the meantime, keep the emails coming in and watch out for the space station in the next few days. there are some more good sighting awaiting all of us.

I briefly blogged yesterday about the massive image of our own galaxy, the milky way, that has been released by the people using the infrared Spitzer Space Telescope.

I just wanted to reiterate that it is really worth taking a look, and there is a great site produced by the team that not only uses the Google Maps interface (.astronomy!) but also highlights some features like nebulae to help the uninitiated viewer.

Take a look!

I recently saw a Digg article which linked to a space.com page about the 10 Strangest Things in Space. All but 2 of the items were not pictures at all but computer simulations, or artists impressions. So here to correct this injustice to phenomena everywhere I present the REAL 10 Strangest Things in Space - or at least in my opinion. Feel free to suggest any others in the comments.

V838 Monoceroti Expansion (Hubble)

It wasn’t anything interesting until it happened but the star V838 Monoceroti, which had simply sat in obscurity, flared up in 2002 to become 600,000 more luminous than our own Sun. It didn’t take long for the star to fade back into the darkness but the Hubble Space Telescope managed to get quite a few pictures of it during its active phase. (Click for animated version)

In this series of images you can see how the star’s outer layers were first expelled and then cut away by the powerful radiation from the star. The event was made even more interesting by the fact that a ‘light echo‘ was seen. During the expansion the object appeared to expand faster than the speed of light - the effect was however merely an astronomical optical illusion.

The Egg Nebula (Hubble)

Also known as CRL2688, the Egg Nebula shows a pair of mysterious ’searchlights’ bursting out from a dense cocoon of dust surrounding a hidden, Sun-like star. We see the light escaping in the directions where the cocoon is thinner. Objects like CRL2688 are rare because they are in a phase of their evolution that is short-lived. Images like this one are very important to understanding how stars like our Sun will ultimately die.

The Sun in UV (SOHO)

The surface of the Sun is far more active than most people would think. This ultraviolet video taken by NASA’s SOHO spacecraft gives brilliant detail. It allows us to see one full revolution of the Sun on its axis, which normally takes about 25 days. In this video you can make out large flares erupting from the surface and the striking magnetic loops that seem to whirl about them as they go. (Full 512×512 MPEG Here)
Red Square Nebula Nebula (Hale/Keck)

Discovered in 2007, this ruby-like nebula may be the result of two interacting stars. If one star is dying then the material from it may be dragged into a disc around the orbits of both objects. Material can then only escape from the system along the poles of the disc, resulting in two cones leading out of the stars. When viewed from the edge these cones seem like two triangles. Here the system is seen in the infrared. Structures like this are rarely seen in nebula but there is in fact a Red Rectangle Nebula which is less symmetric but still quite interesting to look at.

Abell 39 (NOAO)

Here we see an almost perfect planetary nebula that sits about 7,000 light years away in the constellation Hercules. The dot at the centre is the original star, which - as it died - released the expanding gas shell also seen clearly here. The ghostly appearance of the shell is due to the blue-green filter used to take the image, which picks out the oxygen emitted light at 500.7nm.

Saturn’s Rings (Cassini)

This marvelous panoramic view was created by combining a total of 165 images taken by the Cassini wide-angle camera over nearly three hours on Sept. 15, 2006. Cassini was sheltered from the Sun’s glare by positioning itself behind Saturn. Ring structures are revealed here in detail as they brighten substantially at viewing angles where the Sun is almost directly behind the objects. These observations allowed Cassini to detected two new faint rings.

The Horsehead Nebula Swallowed Something (SCUBA)

Observers used the JCMT submillimetre telescope on Mauna Kea in Hawaii to take this image of the familiar Horsehead Nebula, who’s outline can be seen here. When observed at 850 microns, we are seeing the cold dust at temperatures close to absolute zero. This dust is deep inside the optical nebula normally seen, which is transparent at this wavelength. It seems from the image that the Horse has swallowed a ‘lozenge’ which is in fact a region of dense dust that may be collapsing under gravity. In fact this could be a star system in the making.

Gomez’s Hamburger (Hubble)

Arturo Gomez found this odd object in 1985 and it became known as Gomez’s Hamburger for obvious reasons. It is actually a proto-planetary nebula, an earlier version of Abell 39 perhaps. The curves of light (the bun) are reflecting light from the star which is being obscured by a thick band of dust (the burger). The whole thing is only only a fraction of a light year across and located 10,000 light years away in Sagittarius.

The Solar Spectrum (NOAO)

If you could catch a rainbow and put it under a microscope you would see that it was not a continuous blend of colours. Along the width of it would be seen, scattered irregularly, dark patches. Atoms and molecules in the Sun’s atmosphere pick out specific frequencies of light and absorb them, diminishing their intensity by comparison. This images shows the spectrum of light from the Sun stretched out to make these absorption lines visible. We use the reverse of the idea (emission lines) when we make coloured lights. For instance, we excite sodium atoms to emit a signature orange light in street lamps. In this image you can see two prominent dark bands in the yellow-orange section which are the absorption due to sodium.

Update to This Entry

The Sombrero Galaxy in Infrared (Spitzer)

By looking at things in different wavelengths we can see much more than meets the eye. This image is a perfect example. Just as with the Horsehead image above we are seeing cooler material. This time it is dust in the Sombrero galaxy. The red ring is a thick band of dust encircling the whole galaxy. In the optical, this dust ring is what gives the Sombrero its distinctive black, obscuring line.

Oddities in the Orion Nebula (Hubble)

Deep within high resolution images of the Orion Nebula taken by Hubble we can see dark blobs. When you take a closer look you can see that these are like little flattened blobs. Some show a dim, red glow at their centres, others are just dark. These are proto solar-systems.

The red glowing is a protostars attempting to burst through and the dark disks are thick dust regions where one day planets may form. 6 billion years ago, this is what our Solar System may have looked from very far away.

Wednesday’s seminar speaker was Robert Kennicutt, the principal investigator of the SINGS project (Spitzer Infrared Nearby Galaxies Survey). They have been using the Spitzer Space Telescope, launched 2003, to observe the dust content of the nearest galaxies.

Spitzer detects at a wide range of wavelengths in the infrared and submillimeter regimes. This is the part of the spectrum where a vast amount of the universe’s radiation is to be found. Dust absorbs starlight and remits it in this part of the spectrum. There is rather of a lot of dust around and so detecting at these wavelengths gives us valuable information about the structure of objects which may normally be either too bright or too dim to see clearly.

The telescope itself is an 85cm mirror which is cooled to 5.5K. The scope trails the Earth in its orbit around the Sun and is drifting away from the Earth at a rate of 0.1 AU per year. There are three instruments on board, which deliver a wide range of wavelength data. These are detailed as follows (info from Wikipedia).

• IRAC (Infrared Array Camera), an infrared camera which operates simultaneously on four wavelengths (3.6 µm, 4.5 µm, 5.8 µm and 8 µm). The resolution is 256 × 256 pixels.
• IRAS (Infrared Spectrograph), an infrared spectrometer with four sub-modules which operate at the wavelengths 5.3-14 µm (low resolution), 10-19.5 µm (high resolution), 14-40 µm (low resolution), and 19-37 µm (high resolution).
• MIPS (Multiband Imaging Photometer for Spitzer), three detector arrays in the far infrared (128 × 128 pixels at 24 µm, 32 × 32 pixels at 70 µm, 2 × 20 pixels at 160 µm)

The best thing about Spitzer (if you ask me) is the multiple frequencies at which it can image objects in the sky. Shown above is a NASA press release image from Spitzer of the galaxy M81. As you move through the spectrum you are able to see levels of structure inside of the galaxy, which tells us a great deal about what it is made of and how its various parts interact. There are many beautiful images like this one, of several galaxies including the familar Andromeda Galaxy, M31.

I also wanted to share a particularly impressive example of this multiple wavelength instrument with the following image of the Triffid Nebula, M20. This first NOAO, visible light image shows the blue haze of the Triffid with its four, leaf-like segments glowing pinkish. The dark filaments which appear to divide up the lower part of the Triffid are obscuring fingers of dust blocking out the pink light from behind.

Now we can switch to Spitzer’s IRAC and MIPS instrument to see the dust instead. What you see in the greenish image below is the dust which previously was black. I find it particularly gratifying to see that you could almost fit the first image inside the second one. The shape of the original pink and blue clouds appeared carved out of this new version of the object. It seems that M20, as we know it, is indeed cacooned inside a larger conglomoration of dusty material, revealed here by Spitzer.

There is a direct comparison version of this JPEG to found here.

Absolutely incredible and there are many more images like this available. Wonderful! Well done to all the guys and gals working on Spitzer to give the world these fascinating pictures. Gosh that was a vertically-long post.

Researchers using NASA’s Spitzer Space Telescope used the infrared telescope to map temperature variations over the surface of a giant gas planet, HD 189733b, revealing it likely is whipped by roaring winds. Using the data they have created what they call the first weather map of an exoplanet.

You can read more in their Letter to Nature.

“We have mapped the temperature variations across the entire surface of a planet that is so far away, its light takes 60 years to reach us,” said Heather Knutson of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.

The two planets are “hot Jupiters” gas giant planets that orbit around their stars at very short diatances. Roughly 50 of the more than 200 known planets outside our solar system are hot Jupiters. Since 2005, Spitzer has been revolutionizing the study of exoplanets’ atmospheres by examining their infrared light, or heat. HD 189733b is located 60 light-years away and is the closest known transiting planet. That means that it crosses in front and behind its star when viewed from Earth. It orbits its star every 2.2 days.

The observations reveal that temperatures on this balmy world are fairly even, ranging from 650 degrees Celsius (1,200 Fahrenheit) on the dark side to 930 degrees Celsius (1,700 Fahrenheit) on the sunlit side. Since the planet’s overall temperature variation is mild, scientists believe winds must be spreading the heat from its permanently sunlit side around to its dark side. Such winds might rage across the surface at up to 9600 kilometers per hour (6,000 miles per hour). The jet streams on Earth travel at 322 kilometers per hour (200 miles per hour).

You can find more detail at their press release, from which this blog entry was created.

You can also download a nice little movie explaining how the map was created (Quicktime or Windows Media).

NASA researchers using the Spitzer space telescope have laid out what they have called ‘planetary danger zones’ around stars. In these zones, extending from bright O-stars, protoplanetary disks will be swept away by the strong stellar winds given out by the star. Smaller,cooler stars will continue forming planets from accretion disks so long as they remain at least 1.6 light years (10 trillion miles) from any nearby O stars.

Planets form in dusty accretion disks around stars but the powerful O and B type stars bellow out ultra viloet radiation too powerful to allow these disks to remain in tact. They are swept up by the radiation and the protoplanets inside never form. So long as they remain outside any such danger zones, it seems these planets will survive.

The team at NASA surveryed the Rosette Nebula over 5,200 lights years away in the contellation Monoceros. This is a star forming region and a well studied object in the sky. They used Spitzer to observe over 1,000 stars in the vicinty of an O type star and found that only 27 percent of those sytems within 1.6 light years had any kind of disk compared to 45 percent outisde of this danger zone. The image at the top shows the nebula and five of the O stars with their danger zones highlighted.

Stars are not static and do move around, especially within the timescales of planet formation. This study helps scientists to start to pin down the possible speed of planet formation. It could be thet Jupiter-like planets form quickly and would be able to withstand the motion of its parents star toward one these danger zones. Earth-type planets are thought to take longer to form however and would not survive even a brief foray inside sich a barrier.

It is thought that our Sun, like most stars, formed in a group which would have included such powerful O stars. If so then this means the Sun must have migrated out of the group before the planets we are familar with formed. For more on this story check out NASA’s press release.