It’s not always easy being an astronomer whose work is based on observations in the sub-mm, even though this part of the electromagnetic spectrum (think of it as very short wave radio) is perfect for spotting the signatures of the more than 100 molecules which have been detected in space. The problems start when we have to deal with molecules closer to home, however; microwave ovens operate at these frequencies because they can excite the water molecules in food and that also means that it’s especially important for sub-mm telescopes to be high above sea level, away from most of the atmosphere. In one of my early observing runs I managed to make a completely independent detection of ozone in the Earth’s atmosphere which, suffice it to say, was not what I was looking for!
Even after we’ve got over that problem, though, applied for and got our fabulous data of huge scientific importance, when it comes to presenting results it’s hard not to be jealous of everyone else. My office neighbours produce incredible images from optical, infrared, ultraviolet and X-ray telescopes, but the largest sub-mm camera in the world until recently, SCUBA has a few tens of pixels. Not megapixels, but pixels. So when it comes to giving research talks we’ve been rather left behind as far as flashy pictures go.
However, things are changing. When the Sky at Night was last in Hawaii, we featured the new instruments being prepared for the JCMT. SCUBA’s successor, SCUBA2, is moving slowly in the right direction, but the spectral line receiver, HARP, is up and running. Instead of taking a spectrum at each point in a field, HARP makes maps which can be quickly converted into visual representations. I’ve already got my first data, and the first press release came out last week.
This is the centre of the Orion nebula, as seen in emission from Carbon Monoxide (the most common molecule in the Universe behind molecular hydrogen). The real beauty of this data, though, is that we can tune to different frequencies as this schematic shows
When you do that, as in this movie, you get a sense of the motion of the gas. The movie starts with a frequency corresponding to material moving rapidly toward us, at about 200 km/s (half a million miles an hour), and tunes through the different frequencies to end up with material rapidly receeding from us. This is a beautiful illustration of a ‘champagne flow’, as gas is forced away from the central part of the nebula, where star formation is most vigorous.
There will be a lot more from HARP, and from the JCMT in the next few years, and the ability to actually see in the sub-mm will certainly help us get a grip on the surprisingly complicated story of star formation.