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Quark StarsQuark Stars
Kyle DolanKyle DolanAstronomy 4001Astronomy 4001
10 December 200710 December 2007
NASA/Dane Berry
OutlineOutline
• Introduction to Quark Stars (QS)
• Significance of QS
• Characteristics of QS
• Possible examples of QS
• Controversy over the existence of QS
• Possible future observations
Overview of Neutron StarsOverview of Neutron Stars
• Core of a massive star that remains after a supernova explosion
• Average Density: ~1014
g/cm3
• Rotational frequency may range up to 1122 Hz (XTE J1739-285)
• Magnetic field strength can be ~108-1014 times that of Earth
• Exotic Physics!
http://science.nasa.gov/
Quark Stars (QS)Quark Stars (QS)• Stellar core composed of
free quarks (strange matter)
• Would form through neutron deconfinement
• Neutron Star (NS) collapses inward after spinning down, losing centrifugal force
• Strange matter would be “softer”, more compressible than neutrons
• Smaller, denser than a NS• NS massing from 1.5-
1.8MSun are likely candidates http://chandra.harvard.edu
Significance of Quark StarsSignificance of Quark Stars
• Opportunity to study strange matter in nature, and its unique behavior
• Quark novae may explain gamma ray bursts.
NASA/CXC/M Weiss
Quark Star CharacteristicsQuark Star Characteristics
• Smaller Size, indicating densities significantly greater than an atomic nucleus
• High Rotational Frequency– Conservation of angular momentum allows more
compact star to spin faster
• Faster Cooling– Higher-density matter allows production of more
cooling particles (neutrinos) to carry energy away
RXJ1856.5-3754: Possible QS• Discovered in 1996
• Diameter of ≤10km.
• Data suggests that the star is too small to be made of normal neutrons, and could be made of strange matter.
ESO/VLT
XTE J1739-285: XTE J1739-285: Record-Setting PulsarRecord-Setting Pulsar
• Previously known as a normal neutron star, accreting matter from a companion star
• Brightness variations of frequency 1122 Hz observed
• Previous record for rotational frequency was ~700Hz
• High frequency indicates a more compact star, possibly made of strange matter
• May contradict theories of gravitational waves braking rotational speeds
NASA/Dana Berry
3C58 – Possible Quark Nova 3C58 – Possible Quark Nova RemnantRemnant
• Pulsar, possibly the remnant core of SN 1181
• First observed by Chinese and Japanese Astronomers
• Remnant cools by internal collisions that release neutrinos to carry away thermal energy
• Cooling rate is too fast for matter made only of neutrons
• 3C58 would have to be ~5 times as dense as a normal neutron star for this cooling rate to make sense
Chandra X-Ray Observatory
SN 2006gy: Possible Quark NovaSN 2006gy: Possible Quark Nova
• First Observed: 18 September 2006
• 100 times brighter than typical Type II novae
• Neutron deconfinement would blow the outer layers of the NS away at near light speed, to collide with the original supernova debris.
• Observation of elements with A>130 in the debris could confirm 2006gy as a quark nova
NASA/CXC/M Weiss
ControversyControversy
• Possible contradiction of the QS theory:– EXO 0748-676, neutron star with possible mass ~2.1MSun,
indicates too much rigidity for strange matter– Strange matter is too compressible not to collapse in a mass this
large– Mass could be as low as 1.8 MSun, however, which would still fit
QS models
• More observations of XTE are needed to confirm its frequency
• 3C58 may be older than the SN 1181 remnant, due to the lack of variation in its radio emissions
ConclusionsConclusions
• Quark Stars still theoretical, but evidence continues to accumulate to support them
• Quark Stars would offer unique opportunities to study exotic matter
• Helpful Observations for the Future:– Search for exotic elements in nova remnants– Precise determinations of NS radii and rotational
frequency– Close observations of new Supernovae/Quark Novae
SourcesSources“3C58: Pulsar Gives Insight on Ultra Dense Matter and Magnetic Fields.” chandra.harvard.edu. 30 August 2006.
http://chandra.harvard.edu/photo/2004/3c58/
Blaschke, D.B. et al. “Color superconducting quark matter in compact stars.”. arXiv:0712.0117v1. 2 December 2007
Drake, J. J. et al. “Is RX J185635-375 a Quark Star?” arXiv:astro-ph/0204159v1 9 Apr 2002.
“Quark Stars Could Produce Biggest Bang .” spacedaily.com. 7 June, 2006. http://www.spacedaily.com/reports/Quark_Stars_Could_Produce_Biggest_Bang.html
Shiga, David. “Fastest spinning star may have exotic heart.” newscientist.com. 20 February 2007. http://space.newscientist.com/article/dn11221?DCMP=NLC-nletter&nsref=dn11221
Shiga, David. “Massive neutron star rules out exotic matter.” newscientist.com. 28 June 2006. http://space.newscientist.com/article/dn9428-massive-neutron-star-rules-out-exotic-matter.html
Shiga, David. “Was the brightest supernova the birth of a quark star?” newscientist.com. August 2007.http://space.newscientist.com/article/dn12514-was-the-brightest-supernova-the-birth-of-a-quark-star.html
“The leader of the celestial ‘Magnificent Seven.’” scientificblogging.com. 9 March 2007. http://www.scientificblogging.com/news/the_leader_of_the_celestial_magnificent_seven
Xia et al. “Thermal Evolution of Strange Stars.” arXiv:0709.0214v1. 3 September 2007.
Zhang, C.M. et al. “Does Sub-millisecond Pulsar XTE J1739-285 Contain a Low Magnetic Neutron Star or Quark Star?” arXiv:0708.3566v2. 11 September 2007.
Wilford, John Noble. “Stars Suggest a Quark Twist And a New Kind of Matter.” nytimes.com. 11 April, 2002.http://query.nytimes.com/gst/fullpage.html?res=9D04E7DB1F3DF932A25757C0A9649C8B63&sec=&spon=&pagewanted=print