Tempel 1 is weak X-ray source, XMM-Newton confirms

July 5, 2005
Tempel 1 is weak X-ray source, XMM-Newton confirms

ESA's XMM-Newton observations of Comet 9P/Tempel 1 revealed that the object is a weak X-ray source. These data were acquired on 4 July 2005 by one of the EPIC X-ray cameras on board the spacecraft during the post-impact observation phase.

Image: This image of Comet 9P/Tempel 1 was obtained on 4 July 2005 by one of the European Photon Imaging Cameras (EPIC) on board XMM-Newton. With silicon chips that can register extremely weak X-ray radiation, these advanced Charge-Coupled Device cameras (CCD) are capable of detecting rapid variations in intensity, down to a thousandth of a second and less! Credits: ESA. Image by Pedro Rodriguez, ESAC (Spain)

XMM-Newton observed that Tempel 1 emits X-rays, as suspected from previous observations of comets, but this emission is very weak. It is not certain whether it is possible to obtain spectral data which indicate the mechanisms by which the comet's X-rays are produced. Further analysis of the XMM-Newton data is needed to confirm this.

There are two theories to explain why comets emit X-rays. In the first theory, X-rays are produced by a charged exchange between neutral particles present in the comet's coma and ionised particles carried by the solar wind. This has been demonstrated already for several comets in the past.
The second explanation is that the X-rays are just solar X-rays scattered by the dust present in the coma. This could happen during comet outbursts, as observations of Comet Hale-Bopp indicated in 1996. A combination of both mechanisms is also possible.

Even without the task of analysing these weak X-rays, observing the X-ray emission from moving objects like Tempel 1 is already a complex enough task for an X-ray telescope. In fact, XMM-Newton is best suited to studying 'fixed' X-ray sources in the sky. Special planning and processing techniques were required to overcome this observational challenge.

During the observations, XMM-Newton was pointed in the direction of the comet as if it was fixed in the sky, and its instruments were exposed to the radiation (photons) coming from it.

The photons coming from the moving comet were received by the relatively stationary XMM-Newton instruments. Scientists used the arrival time and direction associated with each detected photon to deduce its distance from the comet's nucleus.

Every photon was then 'transformed' mathematically, as if it came from a 'virtual' comet fixed in the sky like the more distant stars. In this way, scientists could treat the comet as a non-moving object.

Scientists then 'cleaned' the data files, by removing those times where the cosmic background radiation was disturbing the observations.

Source: ESA

Explore further: Fresh theories about dark matter

Related Stories

Fresh theories about dark matter

May 15, 2015

Tom Broadhurst, the Ikerbasque researcher in the Department of Theoretical Physics of the UPV/EHU, together with Sandor Molnar of the National Taiwan University and visiting Ikerbasque researcher at the UPV/EHU in 2013, have ...

Recommended for you

'Material universe' yields surprising new particle

November 25, 2015

An international team of researchers has predicted the existence of a new type of particle called the type-II Weyl fermion in metallic materials. When subjected to a magnetic field, the materials containing the particle act ...

CERN collides heavy nuclei at new record high energy

November 25, 2015

The world's most powerful accelerator, the 27 km long Large Hadron Collider (LHC) operating at CERN in Geneva established collisions between lead nuclei, this morning, at the highest energies ever. The LHC has been colliding ...

New gene map reveals cancer's Achilles heel

November 25, 2015

Scientists have mapped out the genes that keep our cells alive, creating a long-awaited foothold for understanding how our genome works and which genes are crucial in disease like cancer.

A blue, neptune-size exoplanet around a red dwarf star

November 25, 2015

A team of astronomers have used the LCOGT network to detect light scattered by tiny particles (called Rayleigh scattering), through the atmosphere of a Neptune-size transiting exoplanet. This suggests a blue sky on this world ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.