Herschel Captures Spectrograph Data on VY Canis Major

It's one of the largest stars ever discovered

By on 28 Nov 2009, 08:35 GMT
Scientists handling the European Space Agency's (ESA) Herschel Space Observatory announce the release of observations performed on one of the largest stars ever known to science, VY Canis Major. The advanced instrument, which was launched in May aboard a modified Ariane 5 delivery system, alongside the Planck Observatory, was able to make out the star using two of its scientific payloads, the Photodetecting Array Camera and Spectrometer (PACS) and Spectral and Photometric Imaging Receiver (SPIRE).

ESA and the respective instrument teams say that the new data were obtained by the advanced space observatory earlier this year, as part of its performance verification phase. The main reason why they were carried out was to show that the instruments aboard the telescope were indeed as advanced as they were advertised be back on Earth. Herschel currently orbit Earth from the L2 Lagrangian point, more than 1.5 million kilometers away from the planet. From its position, it always blocks incoming sunlight or Earth and Moon reflections, which allow it to conduct amazing observations in the Universe.

The Heterodyne Instrument for the Far Infrared (HIFI) was also assessed in the new trials, which come on the heels of previous tests. The latter offered mission controllers a measure of the advanced capabilities that the telescope's video cameras have. Now, the three spectrometers are in the spotlight, having completed a map that shows the distribution of light in the observatory's field of view. “Detailed analyses of these spectra provide insight into the physical and chemical composition of the objects,” ESA experts write on the agency official website.

The new observations also caught the massive star VY Canis Majoris, which is one of the largest ever discovered. Herschel's spectrograph analysis of the object revealed massive amounts of carbon dioxide around the monster star. “That's because carbon and oxygen are two of the most common materials produced in stars and they like to get together, so interstellar space is full of carbon monoxide. From our CO lines we can measure the temperature of the gas and by comparing them with other lines we can also measure density and optical depth and all kinds of other parameters,” explains Cardiff University professor Matt Griffin, the principal investigator of SPIRE, quoted by the BBC News.

“The other lines we're seeing in abundance in both PACS and SPIRE spectra are water. Water is very important astrophysically because it is a diagnostic - it tells us a lot about the physical and chemical processes going on in a gas. And of course water cannot be seen from the Earth because there is so much of it in the atmosphere, its signal gets swamped; and that's why we have to go into space to do these kinds of observations,” he concludes.

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PACS spectra of VY Canis Major
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   PACS spectra of VY Canis Major