Posted by: mattburleigh | April 14, 2010

Observing at 14,000 feet

I’m on Hawaii, spending three nights observing with the NASA Infra-Red Telescope facility (IRTF). It’s a 3m infrared telescope built and funded by NASA to primarily support their robotic missions exploring the solar system with observations from the ground. (That’s an interesting concept – will the new Royal Space Force UK Space Agency be willing to help fund say, a new multi-object spectrograph at the William Herschel Telescope on la Palma to support the Gaia satellite mission? Don’t hold your breath). It also allows access to astronomers with projects to observe all sorts of non-solar system objects. As with all professional telescopes, you simply apply and a panel of experts allocates time to the proposals they rank the highest.

The telescope is on top of Mauna Kea , at almost 14,000 feet, alongside many of the world’s largest and most productive research telescopes (eg Keck, Gemini, Subaru and UKIRT, which we are sadly withdrawing from thanks to the financial crisis in UK astronomy funding).  It’s a wonderful  place, fantastic views (check out the webcams), if a little dangerous to some people’s health (altitude sickness). For that reason the astronomers stay about 5000 feet below the summit at a hostel called the Hale Puhako, and drive up each evening. And it’s OK here: the rooms are a in dire need of re-decorating, but there’s a team of chefs supplying good food round the clock, pool tables, darts, even a gym and launderette, and plenty of office space to work in peace.

I’m taking infra-red spectra of some white dwarf stars® we have discovered in the excellent UKIDSS infrared sky survey, that show unexpected excessive infra-red emission (UKIDSS is the sky survey being carried out by the afore-mentioned UKIRT telescope, which we are pulling the funding from). I want to know if the excess emission is real, and the likely cause: a low mass red dwarf companion, or more interestingly a very rare brown dwarf companion. In one or two cases the emission may even be from a warm dust disk surrounding the star, which may be the remains of an asteroid or small planet that strayed too close to the white dwarf and got shredded apart. The project has been carried out by my recently graduated PhD student Paul Steele, and formed the main thrust of his thesis. One of the aims is to place good statistics on the occurrence and therefore the formation rate of brown dwarfs‡ in binary systems with stars. Hence we need the spectra to confirm the UKIDSS detections and confirm the presence of these companions or dust disks.

So I’m very grateful to the NASA IRTF for giving us time. Unfortunately, Paul couldn’t make it to carry out the observations himself, and I made a last minute trip out here. I hate the travelling, but I’m glad I came. It’s been fun, and a little hard work, learning how to operate a new instrument. There’s two of us in the dome control room: the telescope itself is operated by an IRTF “TO”, Eric Volquardson, who has been very friendly, helpful and patient, and I’m in charge of running the spectrograph. I’m also assisted over conference phone by IRTF astronomer John Raynor, who’s working from his office at sea level. It’s an excellent and impressive set-up: all three of us can see the same instrument control screen, so John could teach me on the first night and then monitor so I don’t foul up too badly. Some astronomers even choose not to travel to Hawaii, and operate the instrument remotely from their own university offices somewhere in the world. But it’s good to have come out here and learnt how to operate another instrument. And importantly, despite a few technical problems in aquiring the targets, I have been able to get some good data. Given the UK’s† determination to run down our investment in astronomy and telescope facilities, I will certainly apply for time here again.

® White dwarf stars are what’s left behind when a star like our own Sun comes to the end of its life. They are basically the super-dense remains of the Sun-like star’s core. Physically they are about the size of the Earth, but packing up to a Sun’s worth of mass into that volume.

‡Objects that are half-way between planets like Jupiter and bona fide stars, although they are basically the same physical size as Jupiter. Sometimes referred to as “sub-stellar”, they have masses up to about 80 times Jupiter’s.

†The Labour Government, the research council (STFC), faceless civil servants, incompetent management, vested interests in the science community: take your pick, choose your conspiracy theory: I’ll be blogging on this topic many times in the future I’m sure.

Yours truly at my station in the NASA IRTF telescope control room

left to right: CFHT, Gemini, UoH 2.2m and UKIRT at sunset. The shadows are Keck and Subaru.

CFHT, Gemini and UoH 2.2m in morning twilight

Cinder cones at the top of Mauna Kea, way above the clouds. Like the surface of Mars?

Subaru, and twin Kecks (world's largest telescopes, 10m mirrors) at sunset


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