Andrew Yee[_1_]
May 22nd 08, 06:05 PM
SRON Netherlands Institute for Space Research
Utrecht, The Netherlands
20 May 2008
Cosmic supermagnet spreads mysterious Morse code
Astronomers from SRON have discovered mysterious pulses that are being
emitted by an extremely magnetic star. The magnetic star, a magnetar, emits
the pulses as very high energy X-rays. The astronomers made their
observations using the ESA space telescopes INTEGRAL and XMM-Newton and the
NASA satellite RXTE.
Sometimes observations confirm a scientific theory perfectly, yet at other
times telescopes bring completely new phenomena to light. That is what
happened in the case of SRON astronomer Peter den Hartog. "I was looking for
new sources of high energy X-rays on a celestial chart, made using the space
telescope INTEGRAL. To our surprise, at the edge of this chart a star was
visible that we knew was a magnetar. However, we never expected that it
would emit this type of radiation," says the researcher, who upon making
this discovery immediately requested additional observation time with
INTEGRAL for follow-up research.
Lighthouse
Magnetars are small compact neutron stars with a magnetic field that is one
billion times stronger than what can be artificially made on Earth. They are
the strongest magnets in the universe. They have a mass one-and-a-half times
that of the Sun but this is squeezed into a sphere with a radius of 10
kilometres. How they form exactly is a mystery. As they emit enormous
quantities of energy in the form of X-rays, they have a lifespan of only
10,000 years. The magnetars rotate like mad around their axes, as a result
of which they regularly sling a bundle of radiation into space like a
lighthouse emitting a beacon of light. Although these X-rays to not reach
the Earth's surface, they are nevertheless visible in space with the aid of
an X-ray telescope.
For a long time astronomers thought that they had understood the nature of
magnetars. The internal energy of a magnetar, stored in the extreme internal
magnetic field that spirals through the star, was emitted as relatively low
energy X-rays. However, that image was overturned several years ago by SRON
astronomer Lucien Kuiper, when he used observations from INTEGRAL to
demonstrate that the magnetars emit far more radiation of a far higher
energy level. The phenomenon of the magnetars was once again shrouded in
mystery. And Peter den Hartog's research has only added to this by revealing
even more striking properties.
Film
"By converting the observations from INTEGRAL, XMM-Newton and RXTE into a
type of short film, we could see how the characteristics of the X-rays
changed over the course of time," explains Den Hartog. The characteristics
of the radiation were found to drastically change during the rotation of the
magnetar. Den Hartog: "Three different processes were found to be taking
place in the magnetar that gave rise to three different pulses." For the
time being, the meaning of this Morse code remains a mystery. This is why
astronomers look with high expectations forward to the first data of space
observatory GLAST due for launch by NASA on the 2nd of June. GLAST will
study the high energy radiation from the universe in detail.
SRON is strongly involved in both INTEGRAL and XMM-Newton. SRON astronomer
Wim Hermsen is a mission scientist in the INTEGRAL team and as such is
closely involved in the satellite's scientific programme. SRON has also
built an instrument for XMM-Newton that unravels the X-rays picked up by the
telescope and then analyses these in detail.
Peter den Hartog defended his PhD thesis entitled 'Non-thermal X-ray
emission from Anomalous X-ray Pulsars' on Wednesday 21 May 2008 at the
Universiteit van Amsterdam.
Utrecht, The Netherlands
20 May 2008
Cosmic supermagnet spreads mysterious Morse code
Astronomers from SRON have discovered mysterious pulses that are being
emitted by an extremely magnetic star. The magnetic star, a magnetar, emits
the pulses as very high energy X-rays. The astronomers made their
observations using the ESA space telescopes INTEGRAL and XMM-Newton and the
NASA satellite RXTE.
Sometimes observations confirm a scientific theory perfectly, yet at other
times telescopes bring completely new phenomena to light. That is what
happened in the case of SRON astronomer Peter den Hartog. "I was looking for
new sources of high energy X-rays on a celestial chart, made using the space
telescope INTEGRAL. To our surprise, at the edge of this chart a star was
visible that we knew was a magnetar. However, we never expected that it
would emit this type of radiation," says the researcher, who upon making
this discovery immediately requested additional observation time with
INTEGRAL for follow-up research.
Lighthouse
Magnetars are small compact neutron stars with a magnetic field that is one
billion times stronger than what can be artificially made on Earth. They are
the strongest magnets in the universe. They have a mass one-and-a-half times
that of the Sun but this is squeezed into a sphere with a radius of 10
kilometres. How they form exactly is a mystery. As they emit enormous
quantities of energy in the form of X-rays, they have a lifespan of only
10,000 years. The magnetars rotate like mad around their axes, as a result
of which they regularly sling a bundle of radiation into space like a
lighthouse emitting a beacon of light. Although these X-rays to not reach
the Earth's surface, they are nevertheless visible in space with the aid of
an X-ray telescope.
For a long time astronomers thought that they had understood the nature of
magnetars. The internal energy of a magnetar, stored in the extreme internal
magnetic field that spirals through the star, was emitted as relatively low
energy X-rays. However, that image was overturned several years ago by SRON
astronomer Lucien Kuiper, when he used observations from INTEGRAL to
demonstrate that the magnetars emit far more radiation of a far higher
energy level. The phenomenon of the magnetars was once again shrouded in
mystery. And Peter den Hartog's research has only added to this by revealing
even more striking properties.
Film
"By converting the observations from INTEGRAL, XMM-Newton and RXTE into a
type of short film, we could see how the characteristics of the X-rays
changed over the course of time," explains Den Hartog. The characteristics
of the radiation were found to drastically change during the rotation of the
magnetar. Den Hartog: "Three different processes were found to be taking
place in the magnetar that gave rise to three different pulses." For the
time being, the meaning of this Morse code remains a mystery. This is why
astronomers look with high expectations forward to the first data of space
observatory GLAST due for launch by NASA on the 2nd of June. GLAST will
study the high energy radiation from the universe in detail.
SRON is strongly involved in both INTEGRAL and XMM-Newton. SRON astronomer
Wim Hermsen is a mission scientist in the INTEGRAL team and as such is
closely involved in the satellite's scientific programme. SRON has also
built an instrument for XMM-Newton that unravels the X-rays picked up by the
telescope and then analyses these in detail.
Peter den Hartog defended his PhD thesis entitled 'Non-thermal X-ray
emission from Anomalous X-ray Pulsars' on Wednesday 21 May 2008 at the
Universiteit van Amsterdam.