Submillimetre Eagle Eyes on Mauna Kea

Issued by: Inge Heyer, Science Outreach Specialist
Joint Astronomy Centre
Email: outreach@jach.hawaii.edu
Tel: +1 808 969 6524
Fax: +1 808 961 6516

Three observatories on Mauna Kea have come together to form the world's most powerful facility for detailed submillimetre imaging. An exploratory project, the Extended SubMillimeter Array (eSMA) connects the signals from the SubMillimeter Array (SMA), consisting of eight dishes with 6-metre diameter, with those from the 15-metre James Clerk Maxwell Telescope (JCMT) and the 10-metre Caltech Submillimeter Observatory (CSO) through fibre-optic cables. During observations the signals from all ten dishes are electronically combined in a large special-purpose computer to create a virtual telescope with a diameter of 782 metres, allowing for an exceptionally sharp view. The eSMA will explore the Universe using light that the human eye cannot see, at wavelengths around 0.8 millimetre. There are many objects in the sky that emit radiation in this submillimetre range, especially the dusty regions in which new stars, planets and even entire galaxies are being born. These clouds of gas and tiny dust particles are completely dark in visible light, but submillimetre waves can penetrate them.

At a dedication ceremony today, Dr Louis Vertegaal of the Netherlands Organisation for Scientific Research (NWO) cut a symbolic ribbon to mark the first scientific results obtained from this historic collaboration. In the presence of dignitaries from participating organizations and the media, all 10 dishes were linked and rotated in unison.

"The eSMA is an example of an international collaboration in astronomy where the result is more than the sum of its parts", says Vertegaal, Director of the Physical Sciences Department of NWO. "The partnership of three observatories on Mauna Kea has delivered a unique submillimetre facility. The first results presented here were obtained in the test phase. They show a glimpse of the discoveries we can expect with a fully commissioned eSMA on planet, star and galaxy formation."

A telescope's power to see faint objects and minute details depends on the size of the surface collecting the light, either a mirror (ultraviolet to infrared wavelengths) or a dish (submillimetre to radio wavelengths). Our ability to build large collecting surfaces is limited by gravity and cost. However, a technique called interferometry allows astronomers to combine the signals from two or more telescopes to obtain an effective collecting surface given by the distance between the telescopes. In this virtual manner the telescope's size can be greatly expanded without actually building a giant dish. While this technique has been used in radio astronomy for over 50 years, it is far more challenging at shorter submillimetre wavelengths. Furthermore, the water vapour in the Earth's atmosphere blocks submillimetre radiation at all but the driest sites and highest altitudes. This makes the three submillimetre observatories at 14,000 ft (4000 m) on Mauna Kea perfect for this undertaking.

Remo Tilanus, astronomer and Head of Operations of the JCMT, says: "It took a lot of hard work and dedication from the staff of the three observatories to install the special equipment and software needed to make the eSMA a reality. Seeing the first astronomical results is just fantastic."

One of the first observations of the eSMA, led by Sandrine Bottinelli from Leiden Observatory, targetted a bright radio source seen through the disk of a foreground spiral galaxy. The spiral galaxy acts as a lens and magnifies and splits the light from the background source in two close images. With its sharp view, the eSMA was able to separate these two images and detect the presence of atomic carbon in the disk of the foreground spiral galaxy where it absorbed the light at a very specific frequency towards the southern image. The background radio source is located so far away that the radiation we detect from it left when the universe was only 20% of its current age. Although seen in front of the background radio source, the spiral galaxy itself is also at a large distance and the observations of the carbon in its disc tell us about the physical conditions of interstellar gas at the time the universe was only 45% of its current age.

Together with complementary data on the carbon monoxide molecule, this is the first time that the ratio of carbon in atomic to molecular form can be determined accurately in such a distant galaxy. This ratio is important since it determines the ability of interstellar clouds to cool down and collapse to form new stars. Atomic carbon also plays an important role in making more complex organic molecules.

"The shape of the absorption profiles suggests that we are probing different evolutionary stages of star-forming clouds. This is exciting since it could indicate whether conditions favorable for the formation of pre-biotic molecules exist in the ~6.4 billion-year old universe, as they do in our present universe.", says Bottinelli.

In a second result obtained by Hiroko Shinnaga (CSO), the eSMA zoomed in on the envelope of a nearby star, called IRC+10216 or CW Leo. This star is in an evolved stage and is close to the end of its life. During this phase a star expels a lot of the gas in its outer layers to form an envelope and, by tracing the hydrogen cyanide molecule (HCN), the eSMA observed for the first time in detail the zone where molecules form from the gas and are being accelerated away.

Shinnaga says: "The mass of IRC+10216 is similar to our Sun, which is expected to end its life in a similar way five billion years from now. The eSMA caught this scene with very high angular and velocity resolution, allowing for a detailed study of formation processes of the molecules and acceleration process of the molecular gas in the envelope. This material will eventually become the building blocks of new stars and new solar systems."

"The eSMA will allow us to make measurements which were not previously possible", says Professor Gary Davis, Director of the JCMT. "The two scientific results obtained so far demonstrate this new capability superbly. The eSMA will enable astronomers to observe in great detail some of the sources which have been studied by the JCMT, acting alone, for the past two decades. As a consequence, we expect to enhance our understanding of the origins of planets, stars and galaxies".

Images

A satellite view of the eSMA, consisting of the SMA (8 small telescopes above the center), the JCMT (under the right tripod-leg), and the CSO (to the right). The grey overlay illustrates the size of the "virtual" telescope created by the eSMA through the combination of the three existing facilities. (Credits: satellite image: Google map; montage: R. Tilanus/JAC)

http://outreach.jach.hawaii.edu/pressroom/2008_eSMA/esma_virtualtel_dish.jpg (JPG image, 1.5 MB)

Illustration of gravitational lensing (not to scale). The light from the distant quasar is bent by the gravitational field of an intervening spiral galaxy placed fortuituously near the line of sight. The bending produces two artifact images of the quasar, which are observed by the eSMA. The spiral galaxy itself is located at large distances from the sun, corresponding to only 45% of the current age of the universe (Credits: spiral(M100): INT/Jacobus Kapteyn Telescope/Johan Knapen/Nik Szymanek; star field: INT/Jacobus Kapteyn Telescope/Cornwall Astronomy School Project; montage: S. Bottinelli)

http://outreach.jach.hawaii.edu/pressroom/2008_eSMA/esma_lensing_concept.jpg (JPG image, 1.4 MB)

Continuum images of the distant quasar and atomic carbon spectra of the intervening galaxy observed by the eSMA. The color scale shows the two artifact images of the distant quasar produced by the gravitational lensing. Absorption by atomic carbon is present in the spectrum observed towards the SW image, indicated that the deflected light actually goes through a molecular cloud located in an arm of the spiral. (Credits: S. Bottinelli, M. Hughes)

http://outreach.jach.hawaii.edu/pressroom/2008_eSMA/esma_cont_spec_press.jpg (JPG image, 1.0 MB)

The picture at the top left shows a deep optical image of the star, IRC+10216, taken with the Canada-France-Hawaii telescope. At the end of its life as a sun-like star, IRC+10216 is shedding its out layers, visible as shells in the picture which obscure the image of the central region in optical light. At millimetre and submillimetre wavelengths the eSMA can penetrate the shells and with its high resolution study the inner envelope of the star in detail, as shown in the artist rendering on the bottom-right. IRC+10216 itself is represented by the red circle at the center. Several hundred million miles above the star's surface, shown as the darker green region, the temperature of the expelled material becomes low enough for dust and molecules to form. Light from the star, which is thousands of times more luminous than our sun, accelerates the dust and gaseous molecular material (such as HCN, KCl, and SiS). Outside of this innermost portion of the dusty envelope, the material reaches a high velocity and is found to have a clumpy distribution, illustrated here as yellow blobs. These eSMA observations are the first time that this acceleration region was spatially resolved and the kinematics could be studied in detail. (Credits: H. Shinnaga)

http://outreach.jach.hawaii.edu/pressroom/2008_eSMA/esma_irc10216_concept.jpg (JPG image, 232 kB)

Dr Louis B.J. Vertegaal of the Netherlands Organisation for Scientific Research cuts a symbolic ribbon to mark the first scientific results obtained from this historic collaboration. From left to right: Stuart Putland (Head of Administration JAC), Dr Tom Phillips (Director CSO), Dr Louis B.J. Vertegaal (NWO), Prof. Gary Davis (Director JAC), Rob Christensen (Site Manager SMA), Dr Antonio Chrysostomou (Associate Director JCMT).

http://outreach.jach.hawaii.edu/pressroom/2008_eSMA/eSMA_ceremony.jpg (JPG image, 3.1 MB)

Notes for Editors

Light Year

One light year is about 10 million million kilometres or 6 million million miles.

Submillimetre Light

Submillimetre wavelengths are much smaller wavelengths than emitted by a typical radio station, but longer wavelengths than light waves or infrared wavelengths. They are typically measured in microns, also called micrometres. One micron is one millionth of a metre, one 10000th of a centimetre, or one 25000th of an inch.

SMA

The Submillimeter Array is a joint venture of the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics and is funded by the Smithsonian Institution and the Academia Sinica.

Harvard-Smithsonian Center for Astrophysics (SAO)

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

ASIAA

The Institute of Astronomy and Astrophysics (ASIAA) was re-established in 1993 after approval by the Academia Sinica Council upon the recommendation of Academician C.C. Lin. The Preparatory Office was inaugurated with Prof. Frank H. Shu chairing the Advisory Panel, and with Dr. Typhoon Lee as the first director. Succeeding directors are Prof. Chi Yuan (1994-1997), Prof. Fred K.Y. Lo (1997-2002), Prof. Sun Kwok (2003-2005), and Prof. Paul T.P. Ho (2002-2003, and Sept. 2005 - present).ASIAA currently has about 120 members, including research scientists, post-doctoral fellows, engineers, and technical and administrative staff. Although the majority of staff of ASIAA is Chinese, it has members from many foreign countries, including Australia, Canada, France, India, Japan, Korea, Switzerland, U.S.A., and Vietnam.

JCMT

The James Clerk Maxwell Telescope (JCMT) is the world's largest single-dish submillimetre-wave telescope. It collects faint submillimetre-wavelength signals with its 15 metre diameter dish. It is situated near the summit of Mauna Kea on the Big Island of Hawaii, at an altitude of approximately 4000 metres (14000 feet) above sea level. It is operated by the Joint Astronomy Centre, on behalf of the UK Science and Technology Facilities Council, the Canadian National Research Council, and the Netherlands Organisation for Scientific Research. More about the James Clerk Maxwell Telescope: http://outreach.jach.hawaii.edu/articles/aboutjcmt/

Science and Technology Facilities Council

The Science and Technology Facilities Council is an independent, non-departmental public body of the Office of Science and Innovation which itself is part of the Department of Innovation, Universities and Skills. It was formed as a new Research Council on 1 April 2007 through a merger of the Council for the Central Laboratory of the Research Councils (CCLRC) and the Particle Physics and Astronomy Research Council (PPARC) and the transfer of responsibility for nuclear physics from the Engineering and Physical Sciences Research Council (EPSRC). We are one of seven national research councils in the UK. The Science and Technology Facilities Council is government funded and provides research grants and studentships to scientists in British universities, gives researchers access to world-class facilities and funds the UK membership of international bodies such as the European Organisation for Nuclear Research, CERN, the European Space Agency and the European Southern Observatory. It also contributes money for the UK telescopes overseas on La Palma, Hawaii, Australia and in Chile, the UK Astronomy Technology Centre at the Royal Observatory, Edinburgh and the MERLIN/VLBI National Facility.

National Research Council Canada

The National Research Council (NRC) is the Government of Canada's premier organization for research and development. It reports to Parliament through the Minister of Industry. It is governed by a council of 22 appointees drawn from its client community. NRC is responsible for, among other things, undertaking, assisting or promoting scientific and industrial research in different fields of importance to Canada, operating and administering any astronomical observatories established or maintained by the Government of Canada, administering NRC's research and development activities, including grants and contributions used to support a number of international activities, and providing vital scientific and technological services to the research and industrial communities. This mandate is discharged to a great extent through the operation of the NRC Industrial Research Assistance Program, the NRC Canada Institute for Scientific and Technical Information and the Canadian Technology Network.

Netherlands Organisation for Scientific Research

The Netherlands Organisation for Scientific Research (NWO) funds thousands of top researchers at universities and institutes and steers the course of Dutch science by means of subsidies and research programmes. NWO is responsible for enhancing the quality and innovative nature of scientific research as equally initiating and stimulating new developments in scientific research, mainly fulfils its task by allocating resources, facilitates, for the benefit of society, the dissemination of knowledge from the results of research that it has initiated and stimulated, and mainly focuses on university research in performing its task. In fulfilling its responsibilities NWO pays due attention to the aspect of coordination and facilitates this where necessary. NWO wants to ensure that Dutch science continues to be amongst the best in the world and that the currently strong position is further strengthened.

CSO

The Caltech Submillimeter Observatory (CSO) owns the 10.4 metre diameter Leighton telescope near the summit of Mauna Kea, one of the world's best sites for submillimetre astronomy. Astronomers can observe the entire range of submillimetre waves (300 -- 1000 micron) at the CSO with high efficiency. The CSO is operated by the California Institute of Technology under a contract from the National Science Foundation.

California Institute of Technology

Caltech is recognized for its highly select student body of 900 undergraduates and 1,200 graduate students, and for its outstanding faculty. Since 1923, Caltech faculty and alumni have garnered 32 Nobel Prizes and five Crafoord Prizes. In addition to its prestigious on-campus research programs, Caltech operates the W. M. Keck Observatory in Mauna Kea, the Palomar Observatory, the Laser Interferometer Gravitational-wave Observatory (LIGO) and the Jet Propulsion Laboratory. Caltech is a private university in Pasadena, California. For more information, visit www.caltech.edu.

National Science Foundation

The National Science Foundation (NSF) is an independent federal agency created by Congress in 1950 "to promote the progress of science; to advance the national health, prosperity, and welfare; to secure the national defense" With an annual budget of about $6.06 billion, we are the funding source for approximately 20 percent of all federally supported basic research conducted by America's colleges and universities. In many fields such as mathematics, computer science and the social sciences, NSF is the major source of federal backing.

Submillimetre Eagle Eyes on Mauna Kea

Images

Notes for Editors

Light Year

Submillimetre Light

SMA

Harvard-Smithsonian Center for Astrophysics (SAO)

ASIAA

JCMT

Science and Technology Facilities Council

National Research Council Canada

Netherlands Organisation for Scientific Research

CSO

California Institute of Technology

National Science Foundation

Media Contacts

Science Contacts

Web links