Revolutionary new camera reveals the dark side of the Universe

A composite image of the Whirlpool Galaxy (also known as M51). The green image is from the Hubble Space Telescope and shows the optical wavelength. The submillimetre light detected by SCUBA-2 is shown in red (850 microns) and blue (450 microns). The Whirlpool Galaxy lies at an estimated distance of 31 million light years from Earth in the constellation Canes Venatici. Credit: JAC / UBC / Nasa

A new camera that will revolutionise the field of submillimetre astronomy has been unveiled on the James Clerk Maxwell Telescope (JCMT) (link opens in a new window) in Hawaii SCUBA-2 is far more sensitive and powerful than previous instruments
and can map areas of the sky hundreds of times faster.

SCUBA-2 will provide unprecedented information on the early life of stars - normally obscured by the remains of the very dust and gas cloud that collapsed under its own gravity to form the star.

"When you look up at the stars, you only see the light they are emitting in the visible part of the spectrum. Many galaxies, including our own Milky Way, contain huge amounts of cold dust that absorbs visible light and these dusty regions just look black when seen through an optical telescope. The absorbed energy is then re-radiated by the dust at longer, submillimetre, wavelengths", explains Professor Gary Davis, Director of the JCMT. "SCUBA-2 has been designed to detect extremely low energy radiation in the submillimetre region of the spectrum. To do this, the instrument itself needs to be even colder. The detectors inside SCUBA-2 have to be cooled to only 0.1 degree above absolute zero [–273.05°C], making the interior of SCUBA-2 colder than anything in the Universe that we know of!"

The project was led by STFC's UK Astronomy Technology Centre (UKATC) in Edinburgh in collaboration with a world-wide consortium of laboratories including four universities (British Columbia, Cardiff, Edinburgh and Waterloo), the US National Institute of Standards and Technology, and the Joint Astronomy Centre, which operates the James Clerk Maxwell Telescope.

Professor Ian Robson, Director of UKATC, said: "The heart of SCUBA-2, the detector arrays, are a huge achievement; a world-first and the technological challenges in making them have been absolutely immense. It is equivalent to going from a primitive wind-on film camera that people over 50 might remember using straight to a modern digital camera all in one step. It is thanks to the ingenuity and abilities of our scientists and engineers that this immense leap in progress has been achieved."

UK, Canadian and Dutch researchers have pioneered observations of the sky in the submillimetre wavelength range (0.4 to 1 millimetre) through their partnership on the James Clerk Maxwell Telescope. SCUBA-2's predecessor, SCUBA (Submillimetre Common User Bolometer Array) produced many new and unexpected discoveries, from a previously unknown population of distant, dusty galaxies (known ever since as 'SCUBA galaxies'), to the first images of cold debris discs around nearby stars, which may indicate the presence of planetary systems.

Commenting on the performance of the new instrument, Professor Wayne Holland of UKATC, and the SCUBA-2 Project Scientist, said: "With SCUBA, it typically took 20 nights to image an area about the size of the full Moon. SCUBA-2 will be able to cover the same area in a couple of hours and go much deeper, allowing us to detect faint objects that have never been seen before."

The increased mapping speed and sensitivity of SCUBA-2 make it ideal for large-scale surveys; no other instrument will be able to survey the submillimetre sky in such exquisite detail. Dr Antonio Chrysostomou, Associate Director of the JCMT said: "SCUBA-2's first task will be to carry out a series of surveys right across the heavens, mapping sites of star formation within our Galaxy, as well as planet formation around nearby stars. It will also survey our galactic neighbours and crucially, will look deep into space and sample the youngest galaxies in the Universe, which will be critical to understanding how galaxies have evolved since the Big Bang."

The data obtained by these surveys will allow a new and precise understanding of star formation throughout the history of the universe, and complements research being carried out on other telescopes such as the Atacama Large Millimetre Array (ALMA), currently undergoing commissioning in Chile.

Notes to editors

Media contacts

Stephanie Hills
STFC Media Manager
Tel: +44 (0)1235 445 398

Dr Holly Thomas
Joint Astronomy Centre
Tel: +1 808 969 6531
Fax: +1 808 961 6516

Dr John Davies
STFC UK Astronomy Technology Centre
Tel: +44 (0)131 668 8348

Science Contacts

Please note that it is best to contact these individuals by email.
Prof Wayne Holland
STFC UK Astronomy Technology Centre
Tel: +44 (0)131 668 8389

Prof Ian Robson
UK Astronomy Technology Centre
Tel: +44 (0)131 668 8438

Dr Antonio Chrysostomou
Joint Astronomy Centre
Tel: +1 808 969 6512

Prof Gary Davis
Joint Astronomy Centre
Tel: +1 808 969 6504

Further information

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 or one 10,000th of a centimetre.

Submillimetre astronomy is most sensitive to very cold gas and dust. For example, a source with a temperature of 10 K (–263°C) emits most of its energy in a broad spectral region centred around 300 microns. Such very cold material is associated with objects in formation, that is, the mysterious earliest evolutionary stages of galaxies, stars and planets. To understand the origins of these most fundamental of astronomical structures, the submillimetre is the waveband of choice.

SCUBA-2 key facts

Size: 3m (height), 2.4m (width), 2.6m (depth)
Weight: 4.5 tonnes (about three times the weight of a typical car)

Temperature of detectors: 0.1K = –272.9°C = –459.2°F

Submillimetre camera with 5120 pixels (4 sub arrays x 1280 pixels) at each wavelength band

Provides a unique wide-field submillimetre imaging capability at 450 and 850 microns
Hundreds of times faster at mapping large areas of sky than predecessor SCUBA to the same signal-to-noise
Uses superconducting transition edge sensors as the light-sensitive elements
Addresses a wide-range of scientific issues including how galaxies, stars and planets form
Acts as a wide-field "pathfinder" for the new generation of submillimetre interferometers (e.g. SMA and ALMA)

The SCUBA-2 project is a collaboration of several observatories or laboratories. The project was led by the UK Astronomy Technology Centre (UK ATC) with the partners:
University of Edinburgh (array structures)
Cardiff University (Focal Plane Units and 1K enclosure)
US National Institute of Standards and Technology (detector arrays and readout)
University of British Columbia, Canada (multi-channel electronics and data reduction software)
University of Waterloo, Canada (multiplexer screening)
Joint Astronomy Centre (infrastructure and software)

A 2001 survey by the US-based Space Telescope Science Institute revealed that scientific results from SCUBA-2's predecessor, SCUBA had been cited almost as often as those from the Hubble Space Telescope, and much more so than those from any other ground-based facility or satellite project.

The project was funded by the Science and Technology Facilities Council (STFC), the JAC, and the Canada Foundation for Innovation.
The UK ATC SCUBA-2 webpage (link opens in a new window)

James Clerk Maxwell Telescope

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
(link opens in a new window)

About National Research Council Canada

Recognized globally for research and innovation, Canada's NRC is a leader in the development of an innovative, knowledge-based economy for Canada through science and technology.
Netherlands Organisation for Scientific Research

The Netherlands Organisation for Scientific Research(NWO) is the principal Dutch science funding body and its mission is to facilitate excellent scientific research in the Netherlands by means of national competition. Each year NWO spends more than 700 million euros on grants for top research and top researchers, on innovative instruments and equipment, and on institutes where top research is performed. NWO funds the research of more than 5300 talented researchers at universities and institutes. Independent experts select proposals by means of a peer review system. NWO facilitates the transfer of knowledge to society.

About STFC

More about → Revolutionary new camera reveals the dark side of the Universe

IN A STAR’S FINAL DAYS, ASTRONOMERS HUNT “SIGNAL OF IMPENDING DOOM”

A Large Binocular Telescope image which shows the supernova in M51 is available here for the media.

COLUMBUS, Ohio – An otherwise nondescript binary star system in the Whirlpool Galaxy has brought astronomers tantalizingly close to their goal of observing a star just before it goes supernova.

The study, submitted in a paper to the Astrophysical Journal, provides the latest result from an Ohio State University galaxy survey underway with the Large Binocular Telescope, located in Arizona.

In the first survey of its kind, the researchers have been scanning 25 nearby galaxies for stars that brighten and dim in unusual ways, in order to catch a few that are about to meet their end. In the three years since the study began, this particular unnamed binary system in the Whirlpool Galaxy was the first among the stars they’ve cataloged to produce a supernova.

The astronomers were trying to find out if there are patterns of brightening or dimming that herald the end of a star’s life. Instead, they saw one star in this binary system dim noticeably before the other one exploded in a supernova during the summer of 2011.

Though they’re still sorting through the data, it’s likely that they didn’t get any direct observations of the star that exploded – only its much brighter partner.

Yet, principal investigator Christopher Kochanek, professor of astronomy at Ohio State and the Ohio Eminent Scholar in Observational Cosmology, does not regard this first result as a disappointment. Rather, it’s a proof of concept.

“Our underlying goal is to look for any kind of signature behavior that will enable us to identify stars before they explode,” he said. “It’s a speculative goal at this point, but at least now we know that it’s possible.”

“Maybe stars give off a clear signal of impending doom, maybe they don’t,” said study co-author Krzystof Stanek, professor of astronomy at Ohio State, “But we’ll learn something new about dying stars no matter the outcome.”

Postdoctoral researcher Dorota Szczygiel, who led the study of this supernova, explained why the galaxy survey is important.

“The odds are extremely low that we would just happen to be observing a star for several years before it went supernova. We would have to be extremely lucky,” she said.

“With this galaxy survey, we’re making our own luck. We’re studying all the variable stars in 25 galaxies, so that when one of them happens go supernova, we’ve already compiled data on it.”
The supernova, labeled 2011dh, was first detected on May 31 and is still visible in telescopes. It originated from a binary star system in the Whirlpool Galaxy – also known as M51, one of the galaxies that the Ohio State astronomers have been observing for three years.

The system is believed to have contained one very bright blue star and one even brighter red star. From what the astronomers can tell, it’s likely that the red star is the one that dimmed over the three years, before the blue star initiated the supernova.

When the Ohio State researchers reviewed the Large Binocular Telescope data as well as Hubble Space Telescope images of M51, they saw that the red star had dimmed by about 10 percent over three years, at a pace of three percent per year.

Szczygiel believes that the red star likely survived its partner’s supernova.

“After the light from the explosion fades away, we should be able to see the companion that did not explode,” she said.

As astronomers gather data from more supernovae – Kochanek speculates that as many as one per year could emerge from their data set – they could assemble a kind of litmus test to predict whether a particular star is near death. Whether it’s going to spawn a supernova or shrink into a black hole, there may be particular signals visible on the surface, and this study has shown that those signals are detectable.

The team won’t be watching our sun for any changes, however. At less than 10 percent of the mass of the star in supernova 2011dh, our star will most likely meet a very boring end.

“There’ll be no supernova for our sun – it’ll just fizzle out,” Kochanek said. “But that’s okay – you don’t want to live around an exciting star.”

This research was supported by the National Science Foundation.

The Large Binocular Telescope is an international collaboration among institutions in the United Sates, Italy, and Germany. The LBT Corporation partners are: the University of Arizona on behalf of the Arizona University System; the Instituto nazionale di Astrofisica, Italy; the LBT Beteiligungsesellschaft, Germany, representing the Max Planck Society, the Astrophysical Institute of Potsdam, and Heidelberg University; the Ohio State University; and the Research Corporation, on behalf of the University of Notre Dame, University of Minnesota, and University of Virginia.

***

Contact:

Christopher Kochanek, (614) 292-5954; Kochanek.1@osu.edu
Dorota Szczygiel, (614) 688-7426; Szczygiel.3@osu.edu

Written by Pam Frost Gorder, (614) 292-9475; Gorder.1@osu.edu

More about → IN A STAR’S FINAL DAYS, ASTRONOMERS HUNT “SIGNAL OF IMPENDING DOOM”

A Yellow Supergiant Progenitor of a Massive Star Supernova in M51

Figure 1: HST pre-supernova image (left)

and Gemini NIRI post-supernova image (right)

Another supernova has exploded in the Whirlpool Galaxy (M51), and now astronomers have identified its unusual progenitor using data from Gemini.



Several amateur astronomers independently discovered the bright supernova, designated SN 2011dh, early in June 2011. The object was quickly classified as a Type IIb supernova based on its spectrum; this class of supernovae likely arises from massive stars that have lost some, but not all, of their outermost layers of hydrogen.



Within hours of the discovery of SN 2011dh a multi-national science team, including Morgan Fraser (Queens University Belfast, UK) triggered their Gemini Target of Opportunity (ToO) program to obtain high-resolution images with the near-infrared camera NIRI at the Gemini North telescope in Hawai‘i. However, snow and poor weather on Mauna Kea (where Gemini North is located) kept the telescope closed for a few nights, delaying the observations.



When observations were again possible, NIRI was successfully used with the adaptive optics system Altair to correct for the blurring effect of the Earth's atmosphere (known as 'seeing'), allowing the team to obtain an image with a resolution matching that of the Hubble Space Telescope. This comparable high resolution was always an intentional part of the plan: the program was designed to target supernovae that happened to occur in galaxies that had already been observed with the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST).



As Fraser describes, “By carefully aligning the image of the supernova, to the pre-explosion HST images, we were able to identify a bright yellow supergiant as coincident with the supernova location in pre-explosion images.” The progenitor candidate has a temperature of about 6000K (which is comparable to that of the Sun), but was 13 times the mass of the Sun at the start of its life, and 100,000 times more luminous when it exploded.



The fact that the progenitor candidate identified is a yellow supergiant poses a challenge for current stellar evolutionary models. Over the last three years, there have been several claimed detections of yellow supergiant progenitors for other supernovae (for SN 2008cn and SN 2009kr). However, in both of these cases, the progenitors were considerably more distant and were detected at two wavelengths, so misidentification is possible. SN 2011dh is considerably closer than either of these supernovae, and the progenitor was detected at multiple wavelengths from the ultra-violet to the near-infrared, so the identification is more secure.



Several theories have been proposed to explain the yellow color of these progenitors, including dust, blended stars due to the poor resolution of some images, or the presence of a binary companion. The team is continuing to observe SN 2011dh, and this ongoing work will shed further light on the properties of the supernova and the variety of ways in which a massive star can end its life.



Prof. Stephen Smartt of Queens University Belfast and a collaborator adds, "This supernova has stimulated great interest and many observers are monitoring it in detail before it disappears behind the Sun in a few weeks time. Already there is debate about whether or not the yellow-supergiant could actually be a companion to the supernova progenitor. That's plausible, but the resolution of the debate will need much more data analysis and perhaps waiting to see if the star has disappeared."



The current work will appear in The Astrophysical Journal Letters, in a paper led by Justyn Maund (Dark Cosmology Centre of the Niels Bohr Institute, University of Copenhagen, Denmark). A preprint is now available.

Source: Gemini Observatory

More about → A Yellow Supergiant Progenitor of a Massive Star Supernova in M51

Supernova Discovered in M51 The Whirlpool Galaxy

M51
Credit: Hubble

A new supernova (exploding star) has been discovered in the famous Whirlpool Galaxy, M51.

M51, The Whirlpool galaxy is a galaxy found in the constellation of Canes Venatici, very near the star Alkaid in the handle of the saucepan asterism of the big dipper. Easily found with binoculars or a small telescope.

The discovery was made on June 2nd by French astronomers and the supernova is reported to be around magnitude 14. More information (In French) can be found here or translated version here.

Supernova in M51
Image by BBC Sky at Night Presenter Pete Lawrence

The supernova will be quite tricky to spot visually and you may need a good sized dobsonian or similar telescope to spot it, but it will be a easy target for those interested in astro imaging.

The whirlpool galaxy was the first galaxy discovered with a spiral structure and is one of the most recognisable and famous objects in the sky.

by Adrian West
Source: Universe Today

Another Nearby Supernova in the Whirlpool Galaxy

Credit & Copyright: Stephane Lamotte Bailey, Marc Deldem,
& Jean-Luc Dauvergne
Source: APOD

More about → Supernova Discovered in M51 The Whirlpool Galaxy