Saturday, September 24, 2011

Astrophysical Studies Assignment

So this post is a project for a masters degree course I'm taking. The assignment states:

"Photographs of stellar birthplaces (i.e. molecular clouds) and death places (e.g. planetary nebulae and supernova remnants) can be strikingly beautiful, but only a few such photographs are included in this chapter. Search the Web for additional images. Look not only for photos taken in visible light, but also for those taken in other wavelengths. Put the photographs you find into a personal online journal, along with a one-paragraph description of what each photograph shows. Include at least 20 images."

I'm pretty excited to not just show some pictures of nebulae but show some of MY pictures. Astrophotography is a hobby of mine and I've got a few pictures to post and discuss. I'll also include a couple pictures from friends and a few "professional" images from the web. Below is a picture of the telescopes and equipment I use:

1. The summer Milky Way

Kind of appropriate since much of our galaxy is made of the gases and dust that stars are made of. The dark lanes you can see through the Milky Way aren't voids of no stars but rather swaths of dust and gas that block the stars beyond. This shot was taken from a photo tripod with a regular DSLR camera on a 30 second timer.

2. A collage of Messier Objects in the Milky Way, including the Trifid Nebula and Ring Nebula.

This is a collection of objects I photographed through an 80mm refractor one summer. Most are open and globular star clusters, but I included the Trifid Nebula - a star forming region, and the Ring Nebula - the expanding shell of a dying star. These objects were cataloged in 1771 by Charles Messier as part of his effort to eliminate stationary deep sky objects (nebulae, galaxies, and star clusters) in his hunt for comets.

3. Ghost of Jupiter Nebula

Named because its faint disk shape resembles a planet through a telescope. It is a planetary nebula that is about 1400 light years away.

4. The Horsehead and Flame Nebulae

For being such a famous nebula, the Horsehead is notoriously difficult to see through amateur telescopes. It is actually a dark cloud of dust and gas superimposed over a dim glowing gaseous hydrogen nebula. Both the Flame and the Horsehead lie just to the bottom left of the left-most star in Orion's Belt.

5. M78

Also near the Constellation Orion, M78 is a reflection Nebula consisting of dark dust and gas which reflects light from nearby stars. Much more spectacular through larger telescopes and more sensitive cameras, I kind of like the challenge of picking out faint Nebulae like this. Like the Horsehead, M78 is part of the Orion Molecular Cloud Complex.

6. The Great Nebula in Orion with the Running Man Nebula.

A photographers' favorite and one you can easily see with the naked eye. Orion lies in the sword, below Orion's belt (seen below in the "map" image of the Orion region.) The super bright central region is home to some very young stars. It's actually not that bright through a telescope - it's just a limit to the camera recording both very bright and very dim areas of the nebula at the same time. The Running Man is the fainter nebula to the left in the wider-field photo (the dark lanes resemble legs and a body).

7. The Orion Constellation

For the next time you see the Orion Constellation. It rises after midnight right now - it will be visible in the evening sky during the winter. This was just taken with a regular camera and lens. Photos with specialized astronomy CCD cameras are impressive, showing bands of red hydrogen clouds stretching in and around the entire constellation.

8. The Lagoon Nebula

Found just above the "spout" of the Sagittarius Constellation "teapot", the Lagoon is discernible as a bright "knot" in the Milky Way and through binoculars looks like a gray cloud. It's 4100 light years away, which should give you a sense of how massive this star-forming region is.

9. M1 - The Crab Nebula

A stunning Supernova remnant high in the winter sky. It corresponds to the bright nebula seen by the Chinese in 1054. Being so recent, the expansion of the nebula has been measured in recent times. The strong pulsar left over in the middle acts as a convenient radiation source that lies along the ecliptic - lending itself as a laboratory tool to study objects that eclipse it (the Sun, Saturn).

10. The Dumbbell Nebula

A unique two-lobed planetary nebula of a dying star. It is relatively large and bright, making it easy to spot even in binoculars (albeit as a faint gray smudge, like many other deep sky objects viewed through amateur optics). It is 1.01 light years across it's semi-major axis.

11. The Seven Sisters

The very recognizable Pleiades is actually an open star cluster of very bright B-type stars. The reflection nebula is actually unrelated to the formation of the cluster and just reflects and diffuses the bright blue light from the stars. Even though it's called the "Seven" Sisters, only 6 stars can be resolved with the naked eye. Maybe the seventh-brightest star - a variable star - was brighter in antiquity, or maybe ancient people just liked seven as a nice round - er, prime, number.

12. The Owl Nebula

The name of course comes from the appearance of the planetary nebula as a face with two big eyes. The "eyes" are likely due to a hollow "donut" hole running through the spherical nebula. It's found just below the bowl of the Big Dipper and is next to the M108 galaxy, seen on the left.

13. The Ring Nebula

Perhaps the Ring is a lot like the Owl Nebula, just seen head on, or "hole-on". It's a planetary nebula found high in the Summer Milky Way. It's a popular target for amateur astronomers due to it's size and faint green color. With a big scope it's stunning. With binoculars, it's elusive - "blinking" in and out of view among a field of stars.

14. The Sombrero and Pinwheel Galaxies

OK, I know these are galaxies not Nebula, but I'm including them for the sake of seeing star-forming regions outside of our own galaxy. The edge-on Sombrero is surrounded by a unique ring of dust which scientists believe is the primary star-forming material in the galaxy. My top-down view of the Pinwheel shows faint knots of nebulosity similar to what you'd find in our own galaxy. Unfortunately I took this picture before the recent supernova in the Pinwheel, or else it would be visible as a bright region in the galaxy. I doubt we'll be seeing the supernova remnant at such a distance though. :)

15. The Cigar Galaxy - Me vs Hubble, Spitzer, and Chandra

The fist pic is one of mine of the Cigar Galaxy. It shows dark star-forming clouds obscuring the galaxy center. The other picture on the other hand is a composite image from Hubble, Spitzer and the Chandra X-ray Observatory of energetic dust and gas surrounding the galaxy. It is definitely one of my favorite pictures.

16. The Propeller Nebula

This is actually a picture my friend took. We started into astrophotography around the same time, but he's invested a lot more time and money into his hobby (if you couldn't tell by the quality). This large star-forming region lies along the Milky Way in Cygnus.

17. The Eagle Nebula with the Pillars of Creation by Hubble

This first one was take by another friend. You can make out the shape of an eagle in flight if you use your imagination. The lower photo is a zoomed in view of the central pillar of gas taken by Hubble. It has been dubbed the Pillars of Creation, as it is stars in the process of being born. Quite inspiring.

18. The North America Nebula

I have to include a few pictures taken by people and equipment much more capable than me and my hobby setup. The North American Nebula is an impressively large nebula in the Summer Milky Way. I like the different pics taken in infrared. The photographers employed a technique known as false color mapping, in which different wavelengths and spectral data is assigned different colors to enhance the details. Can you spot Florida, Mexico and the Gulf of Mexico in the visible light images?

19. The California Nebula

Another pro pic. And another geographical name for it's appearance. The image was taken with a Hydrogen Alpha filter, only showing the light emitted by the changing energy level of hydrogen gas. It's very abundant in the galaxy, but hard to see with the naked eye due to it's faint red color.

20. Hubble's Helix Nebula

Two pictures by Hubble of a planetary nebula. These pics really exhibit the advantage of having a space-based telescope above atmospheric disturbance - really high resolution. You can see the gas and dust being "blown" away from the central star. Interestingly, each of those little "knots" - excluding the tail - is about the size of our solar system.

21. The Tarantula Nebula

One more bonus picture. This nebula is only visible in the Southern Hemisphere and is huge, relatively speaking; 1000 light years across. This image was taken by the Spitzer Space Telescope in the infrared wavelength, demonstrating another advantage of space-based telescopes - getting above the IR-absorbing effects of the atmosphere.