New Images from Planck Reveal Star Formation Processes

An active star-formation region in the Orion Nebula, as seen By Planck. Credits: ESA/LFI & HFI Consortia

While most newborn stars are hidden beneath a blanket of gas and dust, the Planck space observatory – with its microwave eyes – can peer beneath that shroud to provide new insights into star formation. The latest images released by the Planck team bring to light two different star forming regions in the Milky Way, and in stunning detail, reveal the different physical processes at work.

“Seeing” across nine different wavelengths, Planck took at look at star forming regions in the constellations of Orion and Perseus. The top image shows the interstellar medium in a region of the Orion Nebula where stars are actively forming in large numbers. “The power of Planck’s very wide wavelength coverage is immediately apparent in these images,” said Peter Ade of Cardiff University, co-Investigator on Planck. “The red loop seen here is Barnard’s Loop, and the fact that it is visible at longer wavelengths tells us that it is emitted by hot electrons, and not by interstellar dust. The ability to separate the different emission mechanisms is key for Planck’s primary mission.”

A comparable sequence of images, below, showing a region where fewer stars are forming near the constellation of Perseus, illustrates how the structure and distribution of the interstellar medium can be distilled from the images obtained with Planck.

This sequence of images, showing a region where fewer stars are forming near the constellation of Perseus, illustrates how the structure and distribution of the interstellar medium can be distilled from the images obtained with Planck. Credit: ESA / HFI and LFI Consortia

At wavelengths where Planck’s sensitive instruments observe, the Milky Way emits strongly over large areas of the sky. This emission arises primarily from four processes, each of which can be isolated using Planck. At the longest wavelengths, of about a centimeter, Planck maps the distribution of synchrotron emission due to high-speed electrons interacting with the magnetic fields of our Galaxy. At intermediate wavelengths of a few millimeters the emission is dominated by ionized gas being heated by newly formed stars. At the shortest wavelengths, of around a millimeter and below, Planck maps the distribution of interstellar dust, including the coldest compact regions in the final stages of collapse towards the formation of new stars.

“The real power of Planck is the combination of the High and Low Frequency Instruments which allow us, for the first time, to disentangle the three foregrounds,” said Professor Richard Davis of the University of Manchester’s Jodrell Bank Centre for Astrophysics. “This is of interest in its own right but also enables us to see the Cosmic Microwave Background far more clearly.”

Once formed, the new stars disperse the surrounding gas and dust, changing their own environment. A delicate balance between star formation and the dispersion of gas and dust regulates the number of stars that any given galaxy makes. Many physical processes influence this balance, including gravity, the heating and cooling of gas and dust, magnetic fields and more. As a result of this interplay, the material rearranges itself into ‘phases’ which coexist side-by-side. Some regions, known as ‘molecular clouds,’ contain dense gas and dust, while others, referred to as ‘cirrus’ (which look like the wispy clouds we have here on Earth), contain more diffuse material.

Location of the Planck images in Orion and Perseus. ESA / HFI and LFI Consortia, STSci/DSS/IRAS (background image)

Since Planck can look across such a wide range of frequencies, it can, for the first time, provide data simultaneously on all the main emission mechanisms. Planck’s wide wavelength coverage, which is required to study the Cosmic Microwave Background, proves also to be crucial for the study of the interstellar medium.

“The Planck maps are really fantastic to look at,” said Dr. Clive Dickinson, also of the University of Manchester. “These are exciting times.”

Planck maps the sky with its High Frequency Instrument (HFI), which includes the frequency bands 100-857 GHz (wavelengths of 3mm to 0.35mm), and the Low Frequency Instrument (LFI) which includes the frequency bands 30-70 GHz (wavelengths of 10mm to 4mm).

The Planck team will complete its first all-sky survey in mid-2010), and the spacecraft will continue to gather data until the end of 2012, during which time it will complete four sky scans. To arrive at the main cosmology results will require about two years of data processing and analysis. The first set of processed data will be made available to the worldwide scientific community towards the end of 2012.

Source: ESA and Cardiff University

Planck First Light

Strips of the sky measured by Planck. Credit: ESA

One of the newest telescopes in space, the Planck spacecraft, recently completed its “first light” survey which began on August 13. Astronomers say the initial data, gathered from Planck’s vantage point at the L2 point in space, is excellent. Planck is studying the Cosmic Microwave Background, looking for variations in temperature that are about a million times smaller than one degree. This is comparable to measuring from Earth the body heat of a rabbit sitting on the Moon.

The initial survey yielded maps of a strip of the sky, one for each of Planck’s nine frequencies. Each map is a ring, about 15° wide, stretching across the full sky.

The the differences in color in the strips indicate the magnitude of the deviations of the temperature of the Cosmic Microwave Background from its average value, as measured by Planck at a frequency close to the peak of the CMB spectrum (red is hotter and blue is colder).

The large red strips trace radio emission from the Milky Way, whereas the small bright spots high above the galactic plane correspond to emission from the Cosmic Microwave Background itself.

In order to do its work, Planck’s detectors must be cooled to extremely low temperatures, some of them being very close to absolute zero (–273.15°C, or zero Kelvin, 0K).

Routine operations are now underway, and surveying will continue for at least 15 months without a break. In approximately 6 months, the first all-sky map will be assembled.

Within its projected operational life of 15 months, Planck will gather data for two complete sky maps. To fully exploit the high sensitivity of Planck, the data will require delicate adjustments and careful analysis. It promises to return a treasure trove that will keep both cosmologists and astrophysicists busy for decades to come.

Source: ESA

Planck Starts Collecting Light Left Over From Big Bang

Artists concept of the Planck spacecraft. Credit: JPL

As of August 13, 2009, the Planck mission is officially in business. It is now seeing light billions of years old, left over from the Big Bang. From its location in the L2 point, the spacecraft started collecting science data as part of the “First Light Survey” which is intended to check out all the systems. If all goes as planned, these observations will be the first of 15 or more months of data gathered from two full-sky scans.

Researcher Chris North wrote on the Planck website that “the major science results will take quite a while to come out due to the immense amount of computation needed to analyse them, and are expected in around 3 years’ time. These results will be a full-sky map of the Cosmic Microwave Background, and more accurate measurements of the parameters which have governed how our Universe has evolved.”

The mission, which is led by the European Space Agency with important participation from NASA, will help answer the most fundamental of questions: How did space itself pop into existence and expand to become the universe we live in today? The answer is hidden in ancient light, called the cosmic microwave background, which has traveled more than 13 billion years to reach us. Planck will measure tiny variations in this light with the best precision to date.

After the 15 month prime mission, Planck will continue to scan the sky until its coolant runs out.

For more on Planck, check out these websites:

Cardiff University’s Planck website
ESA’s Planck Website
NASA’s Planck website
Planck Blog