Posted on 04/10/2002 5:40:58 PM PDT by PatrickHenry
WASHINGTON (Reuters) - Two weird stars -- one too cold, the other too small to fit known astronomical models -- show evidence for a completely new form of matter, astronomers said on Wednesday.
Scientists believe these stars could be made not of atoms, or even of the sub-atomic particles called neutrons, but of free-floating sub-sub-atomic particles called quarks, and strange quarks at that.
NASA (news - web sites)'s Chandra X-ray Observatory considered the oddball objects by looking at the high level of X-rays they emit. At first, astronomers thought these might be neutron stars, which before this discovery (news - web sites) were the most extreme form of matter known.
Neutron stars are left after big stars explode in blasts called supernovae, and their cores collapse in on themselves. Neutron stars are almost unimaginably dense: a teaspoon of neutron star material weighs a billion tons (1.016 billion tonnes), or as much as all cars, trucks and buses on Earth.
That is because they are composed only of neutrons crammed together, unlike every bit of earthly matter, which is made up of atoms containing neutrons, protons and electrons with lots of space in between.
Astronomers believe the two stars they studied could be even denser that that. Instead of being made of neutrons, they could be made of quarks. Neutrons in a neutron star are made of quarks, but bundled together in relatively roomy groups of so-called confined quarks.
The two stars under observation could be made up of free quarks huddled together, which take up even less space than confined quarks. If that proves true, they would be what astronomers call strange quark stars, objects which have existed so far only in theory.
SMALL, COLD AND EXOTIC
One piece of evidence for this is one of the stars' extremely small size, Jeremy Drake said at a National Aeronautics and Space Administration briefing.
"Until now we've sought to understand nature on the tiniest of scales, involving experiments to look at matter in finer and finer detail," said Drake, of the Harvard-Smithsonian Center for Astrophysics. He said these current observations "might provide a new window on the nature of matter on the tiniest of scales."
His team studied an object known as RXJ 1856, in the constellation Corona Australis, about 400 light-years from Earth. A light-year is the distance light travels in a year, about 6 trillion miles.
Astronomers figured this was a neutron star, but then used the Chandra observatory and the Hubble Space Telescope (news - web sites) to determine its size, which was 10 miles or less in diameter -- below the lower size limit for neutron stars, which range from 12 miles to 20 miles across.
One way to produce such a tiny star, Drake said, would be to squeeze a neutron star down to its constituent quarks, creating a strange quark star.
In the case of the second odd star, astronomer David Helfand of Columbia University studied an object known as 3C58, which is located in the constellation Cassiopeia and is about 10,000 light-years from Earth.
Astronomers in Asia became aware of this object in 1181 when it flamed out as a supernova, Helfand said. Going on this historical record, present-day astronomers calculated that the remnant star should have cooled down to about 35.6 million degrees Fahrenheit by now. In fact, Helfand said, it is only about 1 million degrees C., making it too cool for a neutron star.
Even a neutron star's density would not be enough to squeeze particles out of this object fast enough to cool it down to this temperature, Helfand said. 3C58 would have to be as much as five times as dense for this to happen.
"Our observation suggests that the core of this object is made of a new kind of exotic material," Helfand said.
Interesting. Gravity is too strong to have a neutron star, but not quite strong enough to produce a black hole...
Perhaps one day, people will learn to live like quarks.
Jeez, is it too much to ask the reporter to use the same units in the same paragraph???
The Washington Post Article on this subject is even worse. No indication of the units!
Neutron stars cool off by radiating tiny particles called neutrinos. After 10 years, such a star's temperature should be about five million degrees. After that, it cools more slowly.Given its age, Helfand expected the temperature of 3C58 to be a bit less than two million degrees.
"Our observations show in the case of this remnant that the temperature is far lower than that and the energy being radiated is down by at least a factor of 10 from (what was expected)," he said.
up, down,strange, charmed,bottom and top
All are names for types of Quarks.
Each name also can be come as a red, green or blue.
See page 65 in Stephen Hawking's book A Brief History Of Time
Or just could be calling the star strange.
I was aware of strange quarks, but unaware of whether any kind of ordinary matter collapse can actually leave you with only strange quarks. I forget what a neutron is made of, but I believe all the particles made of quarks require some mix of different ones.
Looking for help with same, I found This Rather Prescient Slide-Show Display.
Neutrons are made up of three quarks, two so-called "down" quarks and one "up" quark. On Earth, free quarks do not exist and while their existence can be inferred from atom smasher data, none has ever been directly observed.For some reason, the normal neutron quarks change flavor and are all strange quarks in the Strange Quark Star. You got it. I suspected but was very unsure.RXJ 1856, however, implies the existence of an entire star made up of free quarks, a so-called "strange quark star." In that case, some of the original up and down quarks would have been transformed into "strange" quarks (hence the name). Quark stars also could exist with an outer shell of neutrons and a core of free quarks.
BTW, that "atom smasher" takes me back to the 50s. How old was the guy who wrote that article?
Hadrons (particles made up of quarks and gluons) are of two types: mesons and baryons. Mesons (such as pions) are made up of a quark and an antiquark; the color charge of the quark cancels the anticolor of the antiquark. Baryons (such as protons and neutrons) are made up of three quarks, and the three color charges (red, green, blue) add up to a colorless particle.
(Geek alert: these quarks are merely the "valence quarks" of the particle; a real hadron is filled with a "sea" of virtual quark-antiquark pairs of all quark flavors.)
Neutrons are made up of two down quarks and an up quark. Protons are made up of two up quarks and a down quark. Other types of baryons also include one or more of the heavier quarks (strange, charm, bottom, top).
There are other states of matter that are permitted by quantum chromodynamics. The most famous is the quark-gluon plasma. In this state, the hadrons lose all integrity, and the quarks and gluons are free to travel throughout the medium, rather than being confined. This requires a fantastic amount of energy, however, and once it cools enough the plasma crystalizes into hadrons.
However.
Most calculations of quark-gluon plasmas include only up and down quarks. This is sensible, because we try to create such plasmas using heavy ions, which are made up of protons and neutrons. But this may not be a good approximation in all cases. Some calculations indicate that if there are enough strange quarks in the plasma, the plasma may be stable. That is, it may represent a lower energy state than the equivalent baryon-number worth of neutrons. If this is the case, then it is possible that a neutron star might spontaneously transition into this state of matter, becoming one giant subatomic particle (and releasing energy in the process). The properties of such a "strange star" would be very different from a standard neutron star.
Kind of makes one wonder why the super conducting super collider project was scrapped. Would have come in handy for researhing these particles.
This strange quark star is not being called a black hole.That makes one wonder what a black hole would be composed of.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.