For immediate release
Issued by: Douglas Pierce-Price, Joint Astronomy Centre
Tel: +1 808 969 6524
Email: outreach@jach.hawaii.edu

(Images, notes, and contact details at bottom)

Elusive young stars can't hide from multi-talented Michelle

UK astronomers have pinpointed for the first time hundreds of newborn stars inside their dusty cocoons, with the help of "Michelle" - one of the most ambitious and technically complicated ground-based instruments ever built. Michelle is a youngster too: it has just celebrated its first birthday on the United Kingdom Infrared Telescope (UKIRT) in Hawaii.

Tamara King, a student from Leeds University, has been using Michelle to look for hundreds of stellar nurseries. Young stars are enshrouded in the dust and gas clouds out of which they formed. These clouds block their light, making it extremely hard to spot the stars.

King first looked at what she suspected was a Massive Young Stellar Object (MYSO) at near-infrared wavelengths with UFTI, the UKIRT Fast-Track Imager. The object is about 10000 years old - young in stellar terms. She saw what looked like an outflowing jet of material, a third of a light year long, and 3000 light years from Earth. She explains "This could be material coming from a young star, but until the star itself is seen we're in the dark."

Enter "Michelle" - short for "Mid-Infrared Echelle Spectrograph". Michelle gathers light with wavelengths in the mid-infrared range, between 8 and 25 microns. It can see through the dust to pinpoint the star. King says "The star shone clearly through the murk, lined up with the outflowing jet. This implies that it is indeed the source of the jet. Our project is looking at hundreds of candidate MYSOs. By unveiling these stellar birthplaces, we're getting one step closer to understanding the complexities of how stars are born and evolve."

Michelle has also been used to study the remnants of old stars known as planetary nebulae, as well as planets, asteroids and comets, the centre of our Galaxy, and other galaxies millions of light years away.

Unfortunately, these are not the only things that shine brightly in the mid-infrared. Every object at or around room temperature shines too, including the Earth's atmosphere, and the telescope itself. Mid-infrared astronomy has been compared to "observing in the daylight, with the telescope on fire"!

Michelle was designed to overcome this - its detector and optics are cooled by liquid helium to temperatures as low as -269 degrees C, just 4 degrees above absolute zero. It is also fitted to UKIRT, an infrared telescope with excellent image quality and thermal stability. Situated 4194 metres above sea level, atop Mauna Kea in Hawaii, UKIRT takes Michelle above much of the Earth's atmosphere.

Unlike most astronomical instruments, the multi-talented Michelle is so flexible that it can quickly switch between the three main types of astronomical observation: imaging, spectroscopy, and polarimetry. Dr Tom Kerr, the UKIRT Michelle Scientist, says "Michelle is a boon to infrared astronomers. Switching from one Michelle mode to another is simple and quick, allowing us to carry out different types of observations in one night. Previously we'd have to use three separate instruments to do this."

Dr Andy Adamson, the Director of UKIRT, adds "Michelle opens up mid-infrared astronomy for the UK astronomy research community. It's a perfect match both for UKIRT and for the excellent skies of Mauna Kea."

Michelle was designed and built at the UK Astronomy Technology Centre (ATC) in Edinburgh, Scotland. Having spent a year on UKIRT, it will be shared with the Gemini North telescope, also on Mauna Kea in Hawaii.

Images

UKIRT images of the Massive Young Stellar Object (MYSO) candidate. On the left is the near infrared image of the surrounding material, made with the UKIRT Fast-Track Imager (UFTI). On the right is the mid-infrared image made with Michelle, showing the deeply embedded star. Images courtesy of Tamara King, University of Leeds, and the Joint Astronomy Centre, Hawaii.

• http://outreach.jach.hawaii.edu/pressroom/2002_michellemyso/michellemyso.jpg [JPEG]
• http://outreach.jach.hawaii.edu/pressroom/2002_michellemyso/michellemyso_large.jpg [large JPEG]
• http://outreach.jach.hawaii.edu/pressroom/2002_michellemyso/michellemyso_large.tif [large TIFF]

Notes to Editors

Massive Young Stellar Objects:

A Massive Young Stellar Object (MYSO) is a star in the early stages of its life, still embedded in the material from which it has formed. The exact evolutionary stage of the young star is difficult to discern because of the extreme obscuration by the surrounding material. The MYSO is still gaining mass, as the surrounding gas spirals down onto it. At the same time, jets of gas are pushed outwards from its poles. Once the star reaches the 'main sequence' of its life, it will be more than ten times as massive as our own Sun.

Michelle:

The Mid-Infrared Echelle Spectrograph (Michelle) is designed to work between the wavelengths of 8 and 25 microns, and is one of the most versatile astronomical instruments ever built. It is the first common-user mid-infrared instrument to use a large 320x240-pixel SBRC Si:As detector array, and to have such a high spectral resolution. Michelle is capable of separating two wavelengths of mid-infrared light which differ by only one part in 30,000.

UKIRT:

The world's largest telescope dedicated solely to infrared astronomy, the 3.8-metre UK Infrared Telescope (UKIRT) is sited near the summit of Mauna Kea, Hawaii, at an altitude of 4194 meters above sea level. It is operated by the Joint Astronomy Centre in Hilo, Hawaii, on behalf of the UK Particle Physics and Astronomy Research Council.

The UK ATC:

The UK Astronomy Technology Centre is located at the Royal Observatory, Edinburgh (ROE). It is a scientific site belonging to the Particle Physics and Astronomy Research Council (PPARC). The mission of the UK ATC is to support the mission and strategic aims of PPARC and to help keep the UK at the forefront of world astronomy by providing a UK focus for the design, production and promotion of state of the art astronomical technology.

Contacts

• Dr. Douglas Pierce-Price, Science Outreach Specialist
  Joint Astronomy Centre, Hawaii
  +1 808 969 6524
  outreach@jach.hawaii.edu
  
• Tamara King
  Dept of Physics and Astronomy, University of Leeds, UK
  +44 113 343 3872
  tlk@ast.leeds.ac.uk
  
• Dr. Tom Kerr, UKIRT Michelle Scientist
  Joint Astronomy Centre, Hawaii
  +1 808 969 6570
  t.kerr@jach.hawaii.edu
  
• Dr. Andy Adamson, Director of UKIRT
  Joint Astronomy Centre, Hawaii
  +1 808 969 6511
  a.adamson@jach.hawaii.edu
  

Web links

JAC press release and information

http://outreach.jach.hawaii.edu/pressroom/2002_michellemyso/

JAC outreach home page

http://outreach.jach.hawaii.edu/