Page 2

§ Contents

  1.   You Should Know — Neutron Star Terminology & Information
            In This Section You Should Know — Definitions from the Astronomical Science of Neutron Stars
  2.   Neutron Stars — Formation
            Imploding Star & Exploding Supernova — The Stellar Object, Pre and Post-Formation
  3.   Supernova, Nebula, Pulsar & Neutron Star
            The Crab Nebula & Supernova — The Crab Pulsar & Neutron Star
  4.   Strange & Exotic Neutron Stars
            Centaurus X-3 & XTE J1739-285 — Photon Bubbles & Fastest Neutron
  5.   The Planet, White Dwarf and Neutron Star - The Three Amigos
            Oldest Known Planet Identified in M4 — Resident of an Unlikely, Rough Neighborhood
  6.    Isolated Neutron Star
            A Speeding Loner on the Stellar Highway — Catching RX J185635-3754
  7.    In The End
            The Extreme Neutron Star — Necessary Fundamental Building Blocks
  8.    Bibliography
            Additional Resources
  9.   Subsequent chapters for neutron Stars under construction
            Gravitational Waves, Neutron in EXO 0748-676, Tumbling Neutrons and Quark Stars

4. Strange & Exotic Neutron Stars

Centaurus X-3Krzeminski's Star & Centaurus X-3 — A Binary Pulsar with photon Bubbles
"Discovery of Kilohertz Fluctuations in Centaurus X-3: Evidence for Photon Bubble Oscillations (PBO) and Turbulence in a High-Mass X-Ray Binary Pulsar" The Astrophysical Journal, Volume 530, Issue 2, pp. 875-889

Centaurus X-3 art"[A]strophysicists today described their discovery of the fastest known X-ray emissions of any collapsed star in the universe." Discovery of kHz QPO from Cen X-3 Krzeminski's Star is a slightly evolved blue supergiant with a mass of 20.5 X sol mass, a radius of 11.8 solar radii and a listed spectral type of O6.5II. It is estimate to be at a distance of 26,000-30,000 light years and have a visual mgnitude of 14.4 with an orbital period for Krzeminski's Star and J112115.2-603724 of 2.09 days, it being the visible component of the occulting spectroscopic binary system that forms the X-ray pulsar called Cen X-3. See: Krzeminski's Star Image credits: Top left Aladin desktop applet v5.018 and left by Fahad Sulehria, Nova Celestia Cick here for a list of pulsars in binary systems compiled by Wm. Robert Johnston.   [13]

accreting binary neutronXTE J1739-285 — Fastest Spinner
"Astronomers using ESA's gamma-ray observatory, Integral, have detected what appears to be the fastest spinning neutron star yet." Integral points to the fastest spinning neutron star PRESS RELEASE, Date Released: Friday, February 16, 2007. Source and Image Credits: European Space Agency & NASA/Dana Berry

"This neutron star shows X-ray bursts and rotates with 1122 revolutions per second. This is the speed record for rotation. It is accelerated by gas falling in from a near partner star. Possibly it isn't even made of neutrons, but of free, extremely dense quarks." XTE J1739-285 from the German website Astronomie: Die Sterne

Green Bank TelescopePointing coordinatesPulsar J0205+6449 — Youngest
Take a set of pointing coordinates, feed them into a radio telescope and resolve the resulting image into the one at right and voila! Pulsar J020+6449 in the Supernovva Remnant 3C58. "Astronomers using the National Science Foundation's (NSF) newly commissioned Robert C. Byrd Green Bank Telescope (GBT) have detected remarkably faint radio signals from an 820 year-old pulsar, making it the youngest radio-emitting pulsar known." Source & image credits: From the German website of H. Heintzmann, Home Page. Image of the GBT from National Radio Astronomy Observatory, Green Bank Telescope

Photon Bubble Oscillations
Photon what? A more recent theoretical developement of binary neutron / pulsar research has to do with what is going on at the poles of the star as it accretes matter from it's companion star. Specifically "...researchers proposed some 10 years ago that when the neutron star is part of a binary system, the matter sucked onto the neutron star from the companion creates an unusual field of radiation bubbles that dance around the polar regions. When these bubbles burst, they produce a shower of X-rays that should be detectable by an X-ray telescope above the Earth's surface."   [14]   The team — in a rare example where both the seminal observations and new supporting theory have been carried out by the same people — conducting research into these "bubbles" decided that the 30,000 light years distance, 4.8 second spinning X-ray pulsar Centaurus X-3 would be the best canidate for their discovery and they were right:

Photon Bubbles"This search resulted in discovery of two distinct quasi-periodic oscillation frequencies at about three thousandths and onethousandth of a second in the emergent radiation from Centaurus X-3, as well as the presence of a broad spectrum that extends to yet higher frequencies than have been found in any known collapsed object."

"The quasi-periodic oscillation frequencies and the properties of the broad spectrum they discovered matched predictions of their theory for photon bubbles in Centaurus X-3, providing the strongest support yet for the existence of photon bubbles in X-ray pulsars." [15]   The image at left illustrates the theory of "Photon Bubble" formation at the magnetic poles of a neutron star. For a complete review see Discovery of kHz QPO from Cen X-3 from Sonoma State University website.

INTEGRAL Finds a 1122 revolutions per second Neutron Dynamo
INTEGRAL satelliteOn October 17 of 2002 the INTEGRAL satellite ( INTErnational Gamma-Ray Astrophysics Laboratory ) was launched into high orbit from Baikonour in Kazakhstan, Russia. Its elliptical orbit is between 10,000 to 153,000 kilometers, half of the distance to the Moon, in order to keep it above Earth's radiation belts. The satellite was developed by the Italian Space Agency ( Italy's Alenia Spazio ) and constructed by the European Space Agency ( ESA ) with support from nearly 30 European companies and scientists from Poland, the Czech Republic, Russia and the USA. [16]   INTEGRAL's continuing missions ( currently in extended operation till December 2012 ) are the detailed study of the many mysterious high energy objects called Gamma Rays and in this capacity it is the most sensitive gamma-ray observatory ever launched. Image: An artist's impression of ESA's orbiting gamma-ray observatory Integral from the ESA website   [17]

"Integral, in collaboration with NASA's Rossi X-ray Timing Explorer (RXTE), has detected what appears to be the fastest spinning neutron star yet. The neutron star XTE J1739-285 was discovered during one of its active phases on 19 October 1999 by RXTE. While Integral was routinely monitoring the bulge of the Galaxy, XTE J1739-285 recently started to come back to life and Integral discovered the first short bursts of X-rays from the object. During the brightest burst, oscillations were taking place at a frequency of 1122 Hz, the highest spin frequency ever recorded. The exact breakup speed depends on the internal conditions of a neutron star, which are not precisely known. The 1122 Hz detection places a serious constraint on neutron star models."   [18]

XTE J1739-285 from AladinAn Object query on star XTE J1739-285 at the Simbad website returned the following basic information: [KRL2007b] 258 Low Mass X-ray Binary. The [KRL2007b] 258 is the INTEGRAL/IBIS All-Sky Survey in Hard X-rays nomenclature or other designator for XTE J1739-285. The catalog's information is presented based on the standard description for astronomical catalogues which in this case, is for the survey information pre and post, conducted with the INTEGRAL satellite. "We present results of an all-sky hard X-ray survey based on almost four years of observations with the IBIS telescope onboard the INTEGRAL observatory." Which is the Abstract description given by the authors for their catalog.

The image at left shows ( circle & arrow ) where XTE J1739-285 is located ( not visible in this image ) in reference to it's stellar surroundings, RA 17 39 53.95 Dec -28 29 46.8. The image is from the Aladin previewer and is in RGB composition format — Red: SERC/SR/MAMA, Green:(average), Blue: SERC/J/MAMA meaning that this image was created with photographic plates obtained at the ESO/SERC for the southern region and digitized at the MAMA facility at the Centre d'Analyse des Images (CAI), Observatoire de Paris.   [19]

5. The Planet, White Dwarf and Neutron Star - The Three Amigos

artist's renderingThe Planet, White Dwarf and Neutron Star
As a result of the explosive formation of neutron stars you might think of them as loners, perhaps the proverbial "odd-man out" — not so. While neutron stars are found in isolatated stellar regions ( the exception rather than the rule ), most are discovered with a companion star from which they are accreting material, as seen above with regard to Centaurus X-3 or XTE J1739-285. In one particular case, the pulsar B1620-26 ( discovered by radio astronomers in 1988 ) and it's white dwarf companion were known to have a third stellar object associated with the pair. But it wasn't until 2003 that Hubble Space Telescope observations of the white dwarf resolved the question as to just what it could be — a stellar object with a mass 2.5 times larger than Jupiter and hence, placing it into the category of planet. But that wasn't the end nor the real surprise that awaited astronomers as they discovered that the planet was approximately 13 billion years old! At left is an artist's rendering of the planet that is orbiting a helium white-dwarf star and the millisecond pulsar B1620-26. Credit: NASA and G. Bacon (STScI).   [20]

Globular cluster M4Position of the M4 pulsarAT LEFT: "Hubble Space Telescope image of stars in globular cluster M4. Marked is a white-dwarf star, which is orbited by the pulsar called PSR B1620-26; this system had been discovered by radio astronomers in 1988. Only the white dwarf is visible in this image. The system has a third companion, the nature of which was subject to a decade-long discussion and research. Now, careful Hubble Space Telescope observations of the white dwarf have helped to reveal the nature of this third companion: It has a mass 2.5 times larger than planet Jupiter, and is thus recognized as a planet." [21]   AT RIGHT: The green circle marks the position of the pulsar orbited by the oldest known planet, a closeup of the image at left. Here's the story of these three amigos, true residents of an unlikely, rough and crowded neighborhood:

"The planet has had a rough road over the last 13 billion years. When it was born, it probably orbited its youthful yellow sun at approximately the same distance Jupiter is from our Sun. The planet survived blistering ultraviolet radiation, supernova radiation, and shockwaves, which must have ravaged the young globular cluster in a furious firestorm of star birth in its early days. Around the time multi-celled life appeared on Earth, the planet and star were plunging into the core of M4. In this densely crowded region, the planet and its sun passed close to an ancient pulsar, formed in a supernova when the cluster was young, that had its own stellar companion. In a slow-motion gravitational dance, the sun and planet were captured by the pulsar, whose original companion was ejected into space and lost. The pulsar, sun, and planet were themselves flung by gravitational recoil into the less-dense outer regions of the cluster. Eventually, as the star aged it ballooned to a red giant and spilled matter onto the pulsar. The momentum carried with this matter caused the neutron star to "spin-up" and re-awaken as a millisecond pulsar. Meanwhile, the planet continued on its leisurely orbit at a distance of about 2 billion miles from the pair (approximately the same distance Uranus is from our Sun)." That neutron star by the way, is spinning just under 100 times per second.   [22]

Another notable aspect about the pulsar's companion planet PSR B1620-26 b — it has been added to one of astronomy's most provocative and potentially impactful catalogs that currently exists: The Extrasolar Planets Encyclopaedia. The catalog was established in February of 1995 and "maintains a database of all the currently known and candidate extrasolar planets, with individual "note" pages for each planet and a full list interactive catalog spreadsheet." see Wikipedia. What are Extrasolar planets?

"It refers to a planet that resides outside our solar system. Now, this might seem pretty obvious, but some of the extra-solar planets that have been detected have been extremely large; planets that have been many times the mass of Jupiter have been detected. When you get that large, they really cease to be planets and are rather low-mass brown dwarfs, or 'failed stars' that are too small to undergo hydrogen fusion and emit their own light. Generally speaking, planets cannot be more than ten times the size of Jupiter or else they are too large. As always though, the debate does not end there since we aren't really sure how brown dwarfs are even formed. The main problem posed with detecting extra-solar planets is that compared to the brightness of the stars they are orbiting, they are extremely dim; planets cannot give off their own light, and so we can only 'see' planets by light that is reflected off them from their stars. With traditional astronomy, it is at the moment impossible to detect these planets since their light is far outshone by the stars they orbit around. Therefore, it has been necessary to use other techniques."   [23]

The reality is that extrsolar planets are hard to detect and even harder to defintively catalog; just the implications of their name however, speaks oceans-full as to where science may be headed regarding these stallar objects.

As for our planet PSR B1620-26 b, an article from the UCLA newsroom noted:

"The giant planet lies in the core of the ancient globular star cluster M4, located 7,200 light-years away in the summer constellation Scorpius. Globular clusters are deficient in heavier elements because they formed so early in the universe that heavier elements had not been cooked-up in abundance in the nuclear furnaces of stars. Some astronomers had argued that globular clusters cannot contain planets — a conclusion supported in 1999 when Hubble failed to find close-orbiting "hot Jupiter"-type planets around the stars of the globular cluster 47 Tucanae. Now, it seems that astronomers were just looking in the wrong place, and that gas-giant worlds orbiting at greater distances from their stars could be common in globular clusters."   [24]

6. Isolated Neutron Star

lone neutron star 1st ROSAT imagelone neutron star HRIRX J185635-3754 — A Speeder Caught on Camera
In 1992 astronomers using the Roentgen Satellite or ROSAT, discovered a bright X-ray source that could not be resolved optically, that is, a verifiably present stellar object at the location they were looking yet, images in visible light revealed zero objects. When word of the discovery was released, it casued astronomers to prick up their ears as a stellar object with that amount of heat and measured luminosity, without counterparts at other wavelengths, are extremely rare. This was the first discovery of object RX J185635-3754, a neutron star that is speeding through the stellar neighborhood. Image at left: "We discovered the X-ray source RX J185635-3754 serendipidously in a ROSAT PSPC image of the Corona Australis dark cloud taken in 1992. The source is bright, at 3.6 counts per second, and has the spectrum of a 57 eV (660,000K) black body. The neutron star is the bright source to the lower right." ( red arrow ). At right, "The ROSAT HRI image yielded an improved position. The neutron star is the bright object in the center. The image is approximately 50 arcmin across." So, it's location was recorded and slated for further survey studies.   [25]

RX J185635-3754 seen in visible lightThen, on September 24, 1997, the HubbleSite NewsCenter released a new image and description of RX J185635-3754, this time in visible light, using the Hubble's Wide Field Planetary Camera 2. "Astronomers using NASA's Hubble Space Telescope have taken their first direct look, in visible light, at a lone neutron star. This offers a unique opportunity to pinpoint its size and to narrow theories about the composition and structure of this bizarre class of gravitationally collapsed, burned out stars." With a neutron star this close ( and getting closer ) astronomers have begun closing in on the theoretical and physical science of these object. Of the next round of surveys, astronomers were able to use the Hubble telescope "in an attempt to determine exactly how far away and how large the star is." The last of these, the size of neutron stars, is important to those theories that set the limits of how small a neutron star should be and why. In addition, it will also give astrophysicists " opportunity to better understand the transition matter undergoes when subjected to the extraordinary pressures and temperatures found in the intense gravitational field of a neutron star." [26]   Image at right: Isolated Neutron Star RX J185635-3754. Credit: Fred Walter (State University of New York at Stony Brook) and NASA

lone neutron star"Astronomers have identified a runaway neutron star that is hurtling in our direction at more than 100 times the speed of a supersonic jet...Astronomers will now study the object's physical properties, such as size, brightness and age, and use it to test their theories about neutron stars...The scientific importance of this object lies in the fact that the neutron star is isolated," said Frederick Walter of the State University of New York...It appears to be hot, not because it is accreting hydrogen gas as it moves through space but because it is still young and cooling off. Since we know its approximate age, we can test how fast neutron stars cool off...Because this is the closest and brightest of the few known isolated neutron stars, it is the easiest to study and is an excellent test-bed for nuclear astrophysical theories." [27]   Image: Hubble Sees Bare Neutron Star Streaking Across Space

RX J185635-3754 seen in X-ray"RX J1856.5-3754 (also called RX J185635-3754, RX J185635-375, and various other designations) is a nearby neutron star in Corona Australis. It is believed to have been created by a supernova explosion of its companion star about one million years ago and is moving 108 km/s across the sky...It was originally thought to be about 150—200 light-years away, but further observations using the Chandra X-ray Observatory in 2002 appear to show that its distance is greater—about 450 light-years." From Wikipedia. Image: X-ray image of RX J1856.5-3754 created by NASA

RX J185635-3754 bowshock nebulaRX J185635-3754 Bowshock & Recent News from the ESA's XMM-Newton Observatory
"To the astronomers' delight and surprise, images and spectra obtained with the ESO Very Large Telescope (VLT) now show a small nearby cone-shaped ("bowshock") nebula. It shines in the light from hydrogen atoms and is obviously a product of some kind of interaction with this strange star. The shape of the cone is like that of a "bowshock" from a ship, plowing through water. Similarly shaped cones have been found around fast-moving radio pulsars and massive stars, cf. e.g., ESO PR 01/97. However, for those objects, the bowshock forms because of a strong outflow of particles from the star or the pulsar (a "stellar wind"), that collides with the interstellar matter." Image: "For clarity, a smaller area around the neutron star and the cone ("bowshock") nebula has been enlarged in PR Photo 23b/00 . The object is at the centre of the circle and the neutron star is indicated with an arrow; the field measures 80 x 80 arcsec 2. XMM-Newton spacecraftNorth is to the lower right and East is upper right. The motion of the neutron star as seen on the sky (see the text) is towards East, exactly in the direction indicated by the nebula." From the ESO website. [28]   While other surveys have been conducted in the intervening period ( e.g. K. Beuermann, F. M. Walter ) RX J185635-3754 remained pretty much on the "theoretical minds" of astronomers in that it seemed to be the best canidate for another type of neutron star — a Quark ( Jeremy J. Drakea and Herman L. Marshall ). A quark star or strange star is a hypothetical type of exotic star composed of quark matter, or strange matter — for a brief overview of Quarks, see Wikipedia. But that thought was recently tested when the neutron speeder was surveyed using the ESA's X-ray space observatory XMM-Newton. This orbiting observatory is the biggest scientific satellite ever built in Europe, its telescope mirrors amongst the most powerful ever developed in the world.

RX J185635-3754 graph of pulaseXMM-Newton finds the leader of the Magnificent Seven in a spin
The X-ray image at left, obtained by the EPIC instrument on-board the ESA XMM-Newton observatory in October 2006 over a 19-hour observation session, shows the neutron star RXJ1856. What the image shows is that neutron star RX J185635-3754 pulsates with a period of seven seconds. "The discovery casts some doubt on the recent interpretation that this object is a highly exotic celestial object known as a quark star...The brightest member of the magnificent seven, RXJ1856 had been a mystery to astronomers since its discovery a decade ago because, despite the fact that it is so bright, no one had been able to find any pulsations and thus determine its rotation rate. That has all changed thanks to the work of Andrea Tiengo and Sandro Mereghetti, Istituto Nazionale di Astrofisica, Milan, Italy." The term "Magnificent Seven" is in reference to a collection of seven young neutron stars. "What sets the magnificent seven apart from the 1700 other neutron stars seen as radio pulsars is that they are not detected at radio frequencies but their surfaces are hot enough to emit X-rays." RX J185635-3754 is the brightest of these.   [29 & 30]

RX J185635-3754 graph of pulaseThere are many good reasons behind the efforts astronomers put into the detailed surveys of stellar objects such as neutron star RX J185635-3754. For starters, this star "is a key object in the study of its stellar category: it provides the second most perfect blackbody spectrum in the Universe, its distance and proper motion are measured, and the pulsations have the smallest pulsed fraction ever seen in an isolated neutron star. Until XMM-Newton's measurements, the knowledge of the rotation period was a missing key ingredient for the understanding of how these objects behave." Secondly, "[n]eutron stars slow down because their strong magnetic fields (one million, million times larger than the Earth's field) and fast rotation, produce electromagnetic radiation that drains their rotational energy. Measuring the deceleration of the object would give astronomers a clue about its magnetic field, which is responsible for creating the hot spot that produces the pulsation." Credit: Image & text from the ESA.

A 2007 article from the Earth Times website on the linking of two satellite observatories ( Japan's Suzaku and Europe's Newton X-ray ) as a new means of studying Neutron stars, pointed out that astronomers at the ESA have seen Einstein's predicted distortion of space-time around three neutron stars. "This is fundamental physics," said Sudip Bhattacharyya at NASA's Goddard Space Flight Center. "There could be exotic kinds of particles or states of matter, such as quark matter, in the centers of neutron stars, but it's impossible to create them in the lab. The only way to find out is to understand neutron stars."   [31]

7. In The End

Artist rendering of Neutron's Magnetic FieldNeutron StarNeutron StarIllustration of B1957+20In the end, it can be said that Neutron stars are objects with very extreme physical properties, existing at the end of a very long stellar evolutionary line. As such, they afford both the astronomer and scientist the opportunity to delve into and study those areas of physics that otherwise wouldn't be possible.   [32]

Final image credits (L to R ):

NASA Neutron Star, Turning Into Rare Ultra-Magnetic Object, Reveals Family Tree Credit: Dr. R. Mallozzi, University of Alabama, Huntsville & NASA.
Neutron Star Image from Stellar Evolution: The Life and Death of Our Luminous Neighbors, by Arthur Holland and Mark Williams
Chandra X-Ray Observatory Illustration of B1957+20, the Black Widow Pulsar
NASA/Honeywell Max Q Digital Group, Dana Berry from computer animation illustrating how neutron stars in our galaxy could be a source of mysterious gamma-ray glows near the galactic plane.   [33]

Stellar evolution is the necessary fundamental building block and distributive method of most common elements in the universe. Within the interior of stars, fusion creates new elements from the basic elements (H, He). While this process takes billions of years as measured by human standards, the life of a star is minor in comparison to the age of the universe.Arthur Holland and Mark Williams

§ Bibliography

  1. Pulsars - Imagine the Universe! at the NASA's Goddard Space Flight Center website, a service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA's Goddard Space Flight Center.
  2. Miller, M. Coleman - Introduction to neutron stars, Mr. Miller is an Associate Professor of Astronomy, University of Maryland
  3. Calculating a Neutron Star's Density - from the RXTE Learning Center, a service of the Astrophysics Science Division at NASA/GSFC.
  4. Miller, Chris - How Black Holes and Neutron Stars Form website Copyright © 1998-2003 by Christopher Miller
  5. Neutron Stars/X-ray Binaries - from the Chandra X-Ray Observatory website's Field Guide
  6. Supernovas - from the Chandra X-Ray Observatory website's Field Guide
  7. Berger, Daniel J. Stars Copyright © 2001 by Daniel J. Berger. The above reprinting of Mr. Berger's work is under the following conditions: "This work may be copied without limit if its use is to be for non-profit educational purposes. Such copies may be by any method, present or future. The author requests only that this statement accompany all such copies. All rights to publication for profit are retained by the author."
  8. Chandra X-Ray Observatory above text quoted from the article Westerlund 1: Neutron Star Discovered Where a Black Hole Was Expected. Release Date: November 02, 2005
  9. 3-D Fly-Through of Cassiopeia A text and video from the Chandra X-Ray Observatory website's Animations & Video: Supernovas & Supernova Remnants page.
  10. Crab Nebula & Pulsar quoted text from the website. © 1998-2008 Sol Company. All Rights Reserved.
  11. Messier 1 quoted text from The Munich Astro Archive © 1995-2005 C. Kronberg. Mr. Kronberg's page is supported by the Universitäts-Sternwarte München and Leibniz-Rechenzentrum München
  12. New Star Appears in Taurus by Von Del Chamberlain, from Project ASTRO UTAH. Determination of the Distance to the Crab Nebula by MATTHEW J. BESTER & MATTEO J. PARIS J. Undergrad. Sci. 3: 57-62 (Summer 1996) Astronomy. "In 2008, the general consensus is that its distance from Earth is 2.0 ± 0.5 kpc (6.5 ± 1.6 kly)." from Wikipedia. Messier 1, Supernova Remnant M1, (NGC 1952) in Taurus Crab Nebula from the SEDS website, Hartmut Frommert & Christine Kronberg, Last Modification: August 22, 2007. M1: Filaments of the Crab Nebula (Info) this is an excellent page of information on the Crab Nebula and it's Pulsar/Neutron Star. These were the primary sources for the quoted distance given to the Crab Nebula.
  13. Krzeminski's Star information retrieved from the Simbad data query site, C.D.S. - SIMBAD4 rel 1.121a - 2009.05.15CEST02:28:22
  14. Fastest known X-ray emissions from a collapsed star support existence of exotic photon bubbles in an X-ray pulsar Created by Tim Graves, 4/7/99, HEAD press release of April 14, 1999
  15. [Ibid], Fastest known X-ray emissions from a collapsed star support existence of exotic photon bubbles in an X-ray pulsar
  16. Integral mission, a closer look at the Gamma Ray Universe from the Astronomy Today website, Author: Paul J. Henney. Copyright © 2000-2009, Astronomy Today.
  17. INTEGRAL mission report from 37th COSPAR meeting, Montreal, Canada 2008, European Space agency. File is in .pdf format.
  18. [Ibid], INTEGRAL mission report from 37th COSPAR meeting
  19. The ALADIN interactive sky atlas. A reference tool for identification of astronomical sources by F. Bonnarel, P. Fernique, O. Bienaymé, D. Egret, F. Genova, M. Louys, F. Ochsenbein, M. Wenger, and J.G. Bartlett, ASTRONOMY & ASTROPHYSICS APRIL I 2000, PAGE 33 SUPPLEMENT SERIES. This file is in .pdf format.
  20. Oldest Known Planet Identified HubbleSite News Release Number: STScI-2003-19 July 10, 2003, Credit: NASA, Brad Hansen (UCLA), Harvey Richer (UBC), Steinn Sigurdsson (Penn State), Ingrid Stairs (UBC), and Stephen Thorsett (UCSC).
  21. SEDS: Oldest Known Planet Identified in M4 from the Students for the Exploration and Development of Space website by Hartmut Frommert and Christine Kronberg.
  22. [Ibid], Oldest Known Planet Identified, HubbleSite News Release Number: STScI-2003-19
  23. A&B's Astronomy Lab, Fall 2001, No. 9 Extrasolar Systems, Aeree Chung & Ben Johnson's Astronomy Lab, Fall 2001
  24. Findings on Farthest and Oldest Known Planet and Companion White Dwarf Reported by UCLA Astronomer, Colleagues Using Hubble Space Telescope Data / UCLA Newsroom By Stuart Wolpert | 7/10/2003, © 2009 UC Regents
  25. RX J185635-3754 - an Isolated Neutron Star from a page written and maintained by F.M. Walter Professor of Astronomy, Department of Physics and Astronomy Stony Brook University, Stony Brook NY 11794-3800 (Last recorded update: 18 March 2003.). Also see Press Release
  26. Hubble Sees a Neutron Star Alone in Space from the HubbleSite News Release Number: STScI-1997-32, September 24, 1997
  27. Lone neutron star speeds through space from the website of the BBC NEWS division of Science/Nature for Friday, 10 November, 2000
  28. The Mystery of the Lonely Neutron Star, VLT images of the RX J1856.5-3754 region ESO Press Release 19/00 11 September 2000
  29. XMM-Newton finds the leader of the Magnificent Seven in a spin article from the ESA website Portal, 9 March 2007. For permission and terms of use see Copuyright page. The findings appear in the 10 March 2007 issue of The Astrophysical Journal, (657: L101—L104, 10 March 2007), in the article by Andrea Tiengo and Sandro Mereghetti (INAF—Istituto di Astrofisica Spaziale e Fisica Cosmica, Milan, Italy) titled: "XMM-NEWTON discovery of 7s pulsations in the isolated neutron star RX J1856.5-3754."
  30. The Magnificent Seven in the dusty prairie The role of interstellar absorption on the observed neutron star population by B. Posselt - S. B. Popov - F. Haberl - J. Trümper - R. Turolla - R. Neuhäuser arXiv:astro-ph/0609275v1 11 Sep 2006. This file in in .pdf format.
  31. Astronomers Pioneer New Method For Probing Exotic Matter article from the NASA/Goddard Space Flight Center Newsletter of August 27, 2007. The XMM-Newton paper appeared in the August 1 Astrophysical Journal Letters. The Suzaku paper has been submitted for publication in the same journal.
  32. [Ibid] M. Coleman Miller, Introduction to neutron stars

Additional Resources

  1. Centaurus X-3 page from Sci-Tech Dictionary. McGraw-Hill Dictionary of Scientific and Technical Terms. Copyright © 2003, 1994, 1989, 1984, 1978, 1976, 1974 by McGraw-Hill Companies, Inc. All rights reserved.
  2. Pulsating Radio Sources near the Crab Nebula Article, David H. Staelin and Edward C. Reifenstein III National Radio Astronomy Observatory, Edgemont Road, Charlottesville, Virginia. Science 27 December 1968: Vol. 162. no. 3861, pp. 1481 - 1483 DOI: 10.1126/science.162.3861.1481 © 2009 American Association for the Advancement of Science. All Rights Reserved.
  3. Integral points to the fastest spinning neutron star "Evidence for 1122Hz X-Ray burst Oscillations from the Neutron-Star X-Ray Transient XTE J1739-285", by P. Kaaret et al., will be published in The Astrophysical Journal on 10 March 2007 (
  4. Researchers Found Crusts of Neutron Stars are 10 Billion Times Stronger than Steel, from the Nanotechnology News Archive, Posted May 6th, 2009, Version 2.0 AZoNano - The A to Z of Nanotechnology...Copyright © 2009 by Pty.Ltd
  5. Discovery of Radio Pulsations from the X-ray Pulsar J0205+6449 in Supernova Remnant 3C 58 With the Green Bank Telescope by F. Camilo, I. H. Stairs, D. R. Lorimer, D. C. Backer, S. M. Ransom, B. Klein, R. Wielebinski, M. Kramer, M. A. McLaughlin, Z. Arzoumanian, and P. Müller Received 2002 March 8; accepted 2002 April 12; published 2002 April 24 The Astrophysical Journal, 571:L41—L44, 2002 May 20 © 2002. The American Astronomical Society. All rights reserved. Printed in U.S.A.
  6. Toward a mass and radius determination of the nearby isolated neutron star RX J185635-3754 from the The Astrophysical Journal 564 (2), 981-1006 (2002), authors: Pons, J. A.; Walter, F. M.; Lattimer, J. M.; Prakash, M.; Neuhäuser, R.; An, P. H.Max-Planck-Institute
  7. Stellar Evolution: The Life and Death of Our Luminous Neighbors by Arthur Holland and Mark Williams, University of Michigan