Tag: pulsar

News from Space: Mysterious Radio Waves Detected…

auriga_nebulaAccording to a story published on July 10 in The Astrophysical Journal, a radio burst was detected that may have originated outside of our galaxy. Apparently, these split-second radio bursts have heard before, but always with the same telescope – Parkes Observatory in Australia. Given that only this observatory was detecting these signals, there was debate about whether they were coming from inside our galaxy, or even from Earth itself.

However, this time the radio signals were detected by a different telescope – the Arecibo Observatory in Puerto Rico – which concluded that the bursts are coming from outside the galaxy. This is also the first time one of these bursts have been found in the northern hemisphere of the sky. Exactly what may be causing such radio bursts represents a major new enigma for astrophysicists.

Victoria Kaspi, an astrophysics researcher at McGill University who participated in the research, explained:

Our result is important because it eliminates any doubt that these radio bursts are truly of cosmic origin. The radio waves show every sign of having come from far outside our galaxy – a really exciting prospect.

arecibo_arrayFast radio bursts are a flurry of radio waves that last a few thousandths of a second, and at any given minute there are only seven of these in the sky on average, according to the Max Planck Institute for Radio Astronomy. Their cause is unknown, and the possibilities range from black holes, to neutron stars coming together, to the magnetic field of pulsars (a type of neutron star) flaring up.

The pulse was detected on Nov. 2, 2012, at the Arecibo Observatory – a National Science Foundation-sponsored facility that has the world’s largest and most sensitive radio telescope. While fast radio bursts last just a few thousandths of a second and have rarely been detected, the international team of scientists reporting the Arecibo finding estimate that these bursts occur roughly 10,000 times a day over the whole sky.

MaxPlanckIns_radiowavepulseThis astonishingly large number is inferred by calculating how much sky was observed, and for how long, in order to make the few detections that have so far been reported. Laura Spitler, a postdoctoral researcher at the Max Planck Institute for Radio Astronomy in Bonn, Germany and the lead author of the new paper, was also the first person to note the event. As she explained:

The brightness and duration of this event, and the inferred rate at which these bursts occur, are all consistent with the properties of the bursts previously detected by the Parkes telescope in Australia.

The bursts appear to be coming from beyond the Milky Way, based on measurement of an effect known as plasma dispersion. Pulses that travel through the cosmos are distinguished from man-made ones by the effect of interstellar electrons, which cause radio waves to travel more slowly at lower radio frequencies. The burst detected by the Arecibo telescope has three times the maximum dispersion measure that would be expected from a local source.

Four_antennas_ALMAEfforts are now under way to detect radio bursts using radio telescopes that can observe broad swaths of the sky to help identify them. Telescopes under construction in Australia and South Africa as well as the CHIME telescope in Canada have the potential to detect fast radio bursts. Astronomers say these and other new facilities could pave the way for many more discoveries and a better understanding of this mysterious cosmic phenomenon.

For those hoping this was a possible resolution to the Fermi Paradox – i.e. that the radio bursts might have been extra-terrestrial in origin – this news is a little disappointing. But in truth, its yet another example of the deeper mysteries of the universe at work. Much like our ongoing research into the world of elementary particles, every answer gives rise to new questions.

Sources: universetoday.com, kurzweilai.net

News from Space: “Earth-Sized Diamond” In Space

White-Dwarf-640x353As our knowledge of the universe beyond our Solar System expands, the true wonder and complexity of it is slowly revealed. At one time, scientists believed that other systems would be very much like our own, with planets taking on either a rocky or gaseous form, and stars conforming to basic classifications that determined their size, mass, and radiation output. However, several discoveries of late have confounded these assumptions, and led us to believe that just about anything could exist out there.

For example, a team of astronomers at the University of Wisconsin-Milwaukee recently identified the coldest, faintest white dwarf star ever detected, some 900 light years from Earth. Hovering near a much larger pulsar, this ancient stellar remnant has a temperature of less than 3,000 K, or about 2,700 degrees Celsius, which made it extremely difficult to detect. But what is especially impressive about this ancient stellar remnant is the fact that it is so cool that its carbon has crystallized.

radio-wave-dishesThis means, in effect, that this star has formed itself into an Earth-size diamond in space. The discovery was made by Prof. David Kaplan and his team from the UofW-M using the National Radio Astronomy Observatory’s (NRAO) Green Bank Telescope (GBT) and Very Long Baseline Array (VLBA), as well as other observatories. All of these instruments were needed to spot this star because its low energy output means that it is essentially “a diamond in the rough”, the rough being the endless vacuum of space, that is.

White dwarves like this one are what happens after a star about the size of our Sun spends all of its nuclear fuel and throws its outer layers off, leaving behind a tiny, super-dense core of elements (like carbon and oxygen). They burn at an excruciatingly slow pace, taking billions and billions of years to finally go out. Even newly transformed white dwarfs are incredibly hard to spot compared to active stars, and this one was only discovered because it happens to be nestled right up next to a pulsar.

White-Dwarf-diamondBy definition, a pulsar is what is left over when a neutron star when a slightly larger sun also runs its course. Those that spin are given the name of “pulsar” because their magnetic fields force radio waves out in tight beams that give the illusion of pulsations as they whir around, effectively strobing the universe like lighthouse. The pulsar that sits next to the diamond-encrusted white dwarf is known as PSR J2222-0137, and is 1.2 times the mass of our sun, but even smaller than the white dwarf.

Astronomers were tipped off to the presence of something near the pulsar by distortions in its radio waves, and an old-fashioned space hunt was then mounted for the culprit. The low mass made a white dwarf the most likely cause, but astronomers couldn’t see it because of its incredibly low luminosity. Because of this, the UofW-M team estimated the age of this object had to be upward of 11 billion years, the same age as the Milky Way Galaxy.

earth-size-diamond-in-space-detected-byastronomersThis meant that the object was already old when our galaxy was just beginning to coalesce. After all those eons to cool off, the star has likely collapsed into a crystallized chunk of carbon mixed with oxygen and some other elements. It could actually be possible, though extremely difficult, to land a spacecraft on an object like this. There may be many more stars in the sky with diamonds, perhaps some even older than this one.

Spotting this white dwarf was a bit of a fluke, though. Until more powerful instruments are devised that can see an incredibly dim, burnt out star, they’ll remain shrouded in the vast darkness of space. However, this is not the first time that an object composed of diamond was found in space by sheer stroke of luck. Remember the diamond planet, a body located some 40 light years from Earth that orbits the binary star 55 Cancri?

diamond_planetYep that one! Like I said, such discoveries are demonstrating that the universe is a much more interesting, awesome, and complex place than previously thought. Between diamond worlds, diamond planets, lakes of methane and atmospheres of plastic, it seems that just about anything is possible. Good to know, seeing as how so much of our plans for the future depend upon on getting out there!

Sources: cnet.com, extremetech.com