Category: Observatories

Caltech has announced it will begin decommissioning the Caltech Submillimeter Observatory (CSO) in Hawaii starting in 2016.

Caltech says the 23-year-old telescope is being replaced by the next generation of radio telescope, the Cornell Caltech Atacama Telescope (CCAT), to be located in Chile.

“The timing of this works very nicely,” says Tom Phillips, director of the CSO and Altair Professor of Physics in Caltech’s Division of Physics, Mathematics and Astronomy. “The international community of astronomers that rely on CSO will have a seamless transition as CCAT comes online just as CSO is decommissioned.”

Located near the summit of Mauna Kea, the CSO began operation in 1986.

The CSO’s 10-meter radio telescope was designed and assembled by a team led by Caltech’s Robert Leighton and is considered one of the easiest telescopes to use for astronomical observations.

Work at the CSO has led to the detection of heavy water on comets, which has helped determine the composition of comets. It has also led to the observation of “dusty” planets–which optical telescopes are often unable to see–allowing astronomers a better picture of a planet’s composition.

“The CSO has a distinguished history of scientific achievement in Hawaii,” says Caltech president Jean-Lou Chameau. “The work done there has led to important advances in astrophysics and made future observatories, such as the CCAT, possible.”

Phillips said it costs about $3 million a year to operate the CSO — an amount that will be better spent on the new telescope. Besides, he said, “Caltech is a world leading research facility and it is not supportive of any activity not satisfying that criterion. The CSO does that today, but it won’t by 2016.”

Caltech operates the CSO under a contract from the National Science Foundation (NSF). Its partners include the University of Texas and University of Hawaii. The observatory has been a host for many scientists worldwide. As part of its mission, observatory time is shared among University of Hawaii researchers, Caltech, the University of Texas, and international partners.

Eleven staff members currently work at the Hilo, Hawaii offices of the observatory while about eight staff members work at Caltech’s Pasadena campus.

When CCAT comes online in the next decade, it will be used to address some of the fundamental questions regarding the cosmos, including the origin of galaxies and early evolution of the universe; the formation of stars; and the history of planetary systems.

CCAT is a joint project of Cornell University, Caltech and its Jet Propulsion Laboratory, the University of Colorado, a Canadian consortium including the University of British Columbia and Waterloo University, a German consortium including the University of Cologne and the University of Bonn, and the United Kingdom through its Astronomy Technology Centre at Edinburgh. More than twice the size of the CSO, the 25-meter CCAT telescope will be located in the high Andes region of northern Chile.

Source: Caltech. The observatory website is here.

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On November 11, 1572 Danish astronomer Tycho Brahe and other skywatchers observed what they thought was a new star. A bright object appeared in the constellation Cassiopeia, outshining even Venus, and it stayed there for several months until it faded from view. What Brahe actually saw was a supernova, a rare event where the violent death of a star sends out an extremely bright outburst of light and energy. The remains of this event can still be seen today as Tycho’s supernova remnant. Recently, a group of astronomers used the Subaru Telescope to attempt a type of time travel by observing the same light that Brahe saw back in the 16th century. They looked at ‘light echoes’ from the event in an effort to learn more about the ancient supernova.

A ‘light echo’ is light from the original supernova event that bounces off dust particles in surrounding interstellar clouds and reaches Earth many years after the direct light passes by; in this case, 436 years ago. This same team used similar methods to uncover the origin of supernova remnant Cassiopeia A in 2007. Lead project astronomer at Subaru, Dr. Tomonori Usuda, said “using light echoes in supernova remnants is time-traveling in a way, in that it allows us to go back hundreds of years to observe the first light from a supernova event. We got to relive a significant historical moment and see it as famed astronomer Tycho Brahe did hundreds of years ago. More importantly, we get to see how a supernova in our own galaxy behaves from its origin.”

On September 24, 2008, using the Faint Object Camera and Spectrograph (FOCAS) instrument at Subaru, astronomers looked at the signatures of the light echoes to see the spectra that were present when Supernova 1572 exploded. They were able to obtain information about the nature of the original blast, and determine its origin and exact type, and relate that information to what we see from its remnant today. They also studied the explosion mechanism.

What they discovered is that Supernova 1572 was very typical of a Type Ia supernova. In comparing this supernova with other Type Ia supernovae outside our galaxy, they were able to show that Tycho’s supernova belongs to the majority class of Normal Type Ia, and, therefore, is now the first confirmed and precisely classified supernova in our galaxy.

This finding is significant because Type Ia supernovae are the primary source of heavy elements in the Universe, and play an important role as cosmological distance indicators, serving as ‘standard candles’ because the level of the luminosity is always the same for this type of supernova.

For Type Ia supernovae, a white dwarf star in a close binary system is the typical source, and as the gas of the companion star accumulates onto the white dwarf, the white dwarf is progressively compressed, and eventually sets off a runaway nuclear reaction inside that eventually leads to a cataclysmic supernova outburst. However, as Type Ia supernovae with luminosity brighter/fainter than standard ones have been reported recently, the understanding of the supernova outburst mechanism has come under debate. In order to explain the diversity of the Type Ia supernovae, the Subaru team studied the outburst mechanisms in detail.

This observational study at Subaru established how light echoes can be used in a spectroscopic manner to study supernovae outburst that occurred hundreds of years ago. The light echoes, when observed at different position angles from the source, enabled the team to look at the supernova in a three dimensional view. This study indicated Tycho’s supernova was an aspherical/nonsymmetrical explostion. For the future, this 3D aspect will accelerate the study of the outburst mechanism of supernova based on their spatial structure, which, to date, has been impossible with distant supernovae in galaxies outside the Milky Way.

The results of this study appear in the 4 December 2008 issue of the science journal Nature.

Source: Subaru Telescope

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A new image of Omega Centauri shows the globular cluster glittering away as one of the finest jewels of the southern hemisphere night sky. It contains millions of stars and is located about 17,000 light-years from Earth in the constellation of Centaurus, and sparkles at magnitude 3.7, appearing nearly as large as the full moon on the southern night sky. Visible with the unaided eye from a clear, dark observing site, when seen through even a modest amateur telescope, the Omega Centauri can be seen as incredible, densely packed sphere of glittering stars. But when astronomers use a professional telescopes, they are able to uncover amazing secrets of this beautiful globular cluster.

This new image is based on data collected with the Wide Field Imager (WFI), mounted on the 2.2-metre diameter Max-Planck/ESO telescope, located at ESO’s La Silla observatory, high up in the arid mountains of the southern Atacama Desert in Chile. Omega Centauri is about 150 light-years across and is the most massive of all the Milky Way’s globular clusters. It is thought to contain some ten million stars!

Recent research into this intriguing celestial giant suggests that there is a medium sized black hole sitting at its center. Observations made with the Hubble Space Telescope and the Gemini Observatory showed that stars at the cluster’s center were moving around at an unusual rate — the cause, astronomers concluded, was the gravitational effect of a massive black hole with a mass of roughly 40,000 times that of the Sun.

The presence of this black hole is just one of the reasons why some astronomers suspect Omega Centauri to be an imposter. Some believe that it is in fact the heart of a dwarf galaxy that was largely destroyed in an encounter with the Milky Way. Other evidence (see here and here) points to the several generations of stars present in the cluster — something unexpected in a typical globular cluster, which is thought to contain only stars formed at one time. Whatever the truth, this dazzling celestial object provides professional and amateur astronomers alike with an incredible view on clear dark nights.

Source: ESO

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Last week’s announcement of a puzzling and unknown source of high energy cosmic rays bombarding the Earth is now joined by another discovery of two sources of unexpected cosmic rays from nearby regions of space. A Los Alamos National Laboratory cosmic-ray observatory has seen for the first time two distinct hot spots that appear to be bombarding Earth with an excess of cosmic rays. “These two results may be due to the same, or different, astrophysical phenomenon, said Jordan Goodman, principal investigator for the Milagro observatory, commenting on last week’s announcement by the ATIC experiment and the new discovery by his team. “However, they both suggest the presence of high-energy particle acceleration in the vicinity of the earth. Our new findings point to general locations for the localized excesses of cosmic-ray protons.” The cosmic rays appear to originate from an area in the sky near the constellation Orion.

Researchers used Los Alamos’ Milagro cosmic-ray observatory to peer into the sky above the northern hemisphere for nearly seven years starting in July 2000. The observatory is unique in that it monitors the entire sky above the northern hemisphere. Because of its design and field of view, Milagro was able to record over 200 billion cosmic-ray collisions with the Earth’s atmosphere.

Cosmic rays are high-energy particles that move through our Galaxy from sources far away. No one knows exactly where cosmic rays come from, but scientists theorize they might originate from supernovae—massive stars that explode— from quasars or perhaps from other exotic, less-understood or yet-to-be-discovered sources within the universe.

“Our observatory is unique in that we can detect events of low enough energies that we were able to record enough cosmic-ray encounters to see a statistically significant fractional excess coming from two distinct regions of the sky,” said collaborator Brenda Dingus.

Because Milagro was able to record so many cosmic-ray events, researchers for the first time were able to see statistical peaks in the number of cosmic-ray events originating from specific regions of the sky near the constellation Orion. The region with the highest hot spot of cosmic rays is a concentrated bulls eye above and to the right visually of Orion, near the constellation Taurus. The other hot spot is a comma-shaped region visually occurring near the constellation Gemini.

But the researchers cannot be sure they have precisely located the sources of the cosmic rays. “Whatever the source of the protons we observed with Milagro, their path to Earth is deflected by the magnetic field of the Milky Way so that we cannot directly tell exactly where they originate,” said Goodman. “And whether the regions of excess seen by Milagro actually point to a source of cosmic rays, or are the result of some other unknown nearby effect is an important question raised by our observations.”

A new, second-generation cosmic ray observatory has been proposed, which may be able to solve the mystery of the origin of cosmic rays. The experiment, named the High Altitude Water Cherenkov experiment (HAWC), would be built at a high-altitude site in Mexico.

Sources: UMD, Science Daily