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V1647 Ori |
In July 2004 an international team of astronomers reported on observations of an X-ray outburst from the rapidly accreting young star that illuminates McNeil's nebula. Astronomers detected a factor 50 increase in the X-ray flux from the star now named V1647 Ori. Astronomers believe that observations of this kind provide important new information about the early evolution of stars like the Sun and the process of planet formation. McNeil's nebula was discovered by Kentucky amateur astronomer Jay McNeil in January 2004 (ref: Nature, July 2004).
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 25:08:2004 |
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H1504 65 |
In June 2004 an international team of astronomers reported the discovery of a remarkable object where the nuclear reactor that once powered it has only just shut down. The surface of the hottest known white dwarf, H1504 65 is virtually free of hydrogen and helium, something never before observed in any star. Astronomers believe that the star shut down nuclear fusion about a hundred years ago. They consider the discovery as a wonderful opportunity to improve their understanding of the life-cycle of stars (ref: Astronomy & Astrophysics, July 2004).
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28:07:2004 |
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Brown dwarf binary system 2MASS J11011926-7732383AB |
In July 2004 astronomers with the Harvard Smithsonian Center for Astrophysics announced the discovery of a unique pair of newborn brown dwarfs in orbit around each other. All previously known pairs of brown dwarfs are relatively close to each other, less than half the distance of Pluto from the Sun. The separation of a new system, 2MASS J11011926-7732383AB, is about six times the distance of Pluto from the Sun. Astronomers believe that this discovery will tell them more about the origin and nature of brown dwarfs. Astronomers used one of the two 6.5-meter-diameter Magellan telescopes at Las Campanas Observatory in Chile (ref: Harvard-Smithsonian Center for Astrophysics press release, July 2004, submitted to ApJ).
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21:07:2004 |
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2MASSW J0746425 2000321 |
In June 2004 an international team of astronomers reported for the first time the measurement of the mass of an ultra-cool star and its companion brown dwarf. The system, 2MASSW J0746425 2000321, is located 40 light-years away. The heavier of the two stars has a mass around 8.5% of the mass of the Sun and its brown dwarf companion is only 6% of the solar mass. Astronomers used ESO's Very Large Telescope at Paranal and a suite of ground- and space-based telescopes in a four-year long study (ref: ESO Press Release 16/04, to be published in Astronomy & Astrophysics).
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07:07:2004 |
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WR 20a |
In May, 2004 astronomers with the Harvard-Smithsonian Center for Astrophysics have presented their work on accurate determination of parameters for WR 20a, which is an eclipsing binary system. Astronomers have found that the mass of each of the two components of WR 20a is about 80M, which makes this system the most massive binary known with an accurate mass determination. The system is located 20,000 light-years from Earth. Two stars orbit each other every 3.7 days. The discovery was made using 1.3-meter-diameter telescope at the Las Campanas Observatory in Chile. (ref: astro-ph/0405338, accepted for publication in ApJL).
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15:06:2004 |
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2MASS J04151954-0935066 |
In January 2003 astronomers from the U.S. Naval Observatory (USNO) and UCLA reported the discovery of the coldest and faintest known star, a brown dwarf located 19 light-years from the Sun in the constellation Eridanus. The Naval Observatory astronomers were able to deduce the cold temperature of this star, known as 2MASS J04151954-0935066, by determining its distance from the Sun. Brown dwarfs such as 2MASS J04151954-0935066 are so cold that they emit almost no visible light. Astronomers used a technique called parallax measurement based on a new generation of infrared array detectors to determine the distance to the star. Its size was roughly estimated as the same as that of Jupiter (ref: U.S. Naval Observatory Press Release, January 2003).
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31:05:2004 |
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WR 93b |
In March 2004 an international team of astronomers reported the discovery of a particularly rare type of emission line star. The star WR 93b has been revealed as only the fourth massive WO star to be found in the Milky Way, and only the seventh identified within the Local Group. The star is most likely located in the Scutum-Crux Arm of the inner Milky Way (ref: astro-ph/0403482, accepted for publication in MNRAS main journal).
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24:05:2004 |
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2MASS J05325346 8246465 |
In August 2003 a team of American astronomers reported the discovery of a new cool subdwarf, identified in the 2MASS database. Astronomers classify the object as a metal-deficient, late-type L dwarf. It's the first L-type subdwarf discovered (ref: ApJ, August 2003).
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17:05:2004 |
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HE0107-5240 |
In October 2002 an international team of astronomers reported the discovery of a star in our galaxy which consists virtually only of hydrogen and helium. The star, designated HE 0107-5240, has the lowest abundance of heavier elements ever observed, only 1/200,000 of that of the Sun - 20 times less than the previous record-holding star. This is the oldest star in our Milky Way yet observed by astronomers. Astronomers believe that this is the closest they have ever come to the conditions directly after the Big Bang by studying stars. The newly discovered star, which lies 36,000 light-years from Earth, is about four-fifths the mass of the Sun (ref: Nature, October 2002)
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11:05:2004 |
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Brown dwarf HR 7672B |
In May 2002 astronomers reported the discovery of a companion to a star much like our Sun. Using adaptive optics on the Gemini North and Keck telescopes, astronomers found the brown dwarf orbiting about 1.3 billion miles from the star known as HR 7672 in the constellation Sagitta, located about 58 light years from Earth. The research team estimates the mass of the brown dwarf at 55 to 78 times the mass of planet Jupiter. The faint companion HR 7672B is separated from its parent star by less than the distance between the Sun and the planet Uranus and is the smallest separation brown dwarf companion seen with direct imaging (ref: ApJ, May 2002).
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11:05:2004 |
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Brown dwarf 2MASSI J0104075-005328 |
Scientists have discovered a new brown dwarf - one of the hardest types of stellar objects to find - using a new approach to finding undiscovered objects buried in immense astronomical databases. An early demonstration of the National Virtual Observatory (NVO) yielded the surprising result. The star was found during a computerized search of information on millions of astronomical objects in two separate astronomical databases. Thanks to an NVO prototype, that search, formerly an endeavor requiring weeks or months of human attention, took approximately two minutes (ref: National Virtual Observatory news release, March 2003).
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26:04:2004 |
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White dwarf binary system RX J0806.3 1527 |
In March 2002 an international team of astronomers reported the discovery of an exceptional binary star system. The system, designated RX J0806.3 1527, was first discovered as an X-ray variable source. The new observations have shown that it’s actually a pair of white dwarf stars that revolve around each other at a distance of only 80,000km. Each of the stars is about as large as the Earth and their period of 321 seconds is the shortest orbital period known for any binary stellar system. Astronomers used European Southern Observatory's Very Large Telescope (ref: Astronomy & Astrophysics Letters, April 2002).
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19:04:2004 |
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JO25300.5 165258 |
In May 2003 a team of American astronomers reported the discovery of a star that may be the third closest to the Sun. The star, JO25300.5 165258 is a faint red dwarf estimated to be about 7.8 light-years from Earth in the direction of the constellation Aries. It was first found in NEAT program images and then observed using 3.5-meter Astrophysical Research Consortium telescope at the Apache Point observatory (ref: ApJ Letters, May 2003).
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12:04:2004 |
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LHS 2397a binary system |
On May 2002 astronomers from the University of Arizona reported a discovery of a companion to the star, known as LHS 2397a, which is about 46 light-years from Earth. The companion, a brown dwarf, orbits a star at a distance of about just three times the distance between the Earth and Sun. This is the closest distance between a star and its companion ever found for this type of binary system using direct imaging. The newly identified brown dwarf is estimated to be between 38 and 69 times more massive than Jupiter. Astronomers used adaptive optics technology on the Gemini North Telescope (ref: Gemini Observatory press release, May 2002).
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05:04:2004 |
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GRS1915 105 X-ray binary system |
In November 2001 German and Chilean astronomers reported a direct measurement of orbital parameters and mass function of GRS1915 105 X-ray binary system in the Milky Way Galaxy, which consists of a low-mass star and a black hole. Using the VLT 8.2-m ANTU telescope at the ESO Paranal Observatory astronomers found that the black hole has 14 times more mass than the Sun, making it the heaviest known stellar black hole in the Galaxy. Such black holes with masses > 5–7 M challenge the conventional picture of black-hole formation in binary systems. RS1915 105 also belongs to a group dubbed 'microquasars' (ref: Nature, November 2001).
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29:03:2004 |
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Brown dwarf binary system Epsilon Indi B |
An international team of astronomers using the Gemini South telescope in Chile announced in August 2003 that recently discovered closest known brown dwarf Epsilon Indi B has a companion Epsilon Indi Bb that appears to be another, cooler brown dwarf. A nearby brown dwarf companion to Epsilon Indi, the fifth brightest star of the southern hemisphere constellation Indus, Epsilon Indi B has been discovered by a team of European astronomers in January 2003 (ref: IAUC 8188).
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22:03:2004 |
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Binary star system KH 15D |
Using archival sky photographs from Harvard College Observatory, in Massachusetts, and Asiago Observatory, in Italy, astronomers were able to explain a strange star called KH 15D, which winks on an off, sometimes with eclipses that last 24 hours. The system is unusual in that there is something blocking the light from the stars, which is supposed to be a disk of dust that surrounds both of the stars.
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15:03:2004 |
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Rosette HH1 |
Using the Wisconsin-Indiana-Yale-NOAO (WIYN) 3.5-meter telescope at the Kitt Peak National Observatory in Tucson, Arizona, in combination with the 2.16-meter telescope of the National Astronomical Observatories of China, a pair of astronomers captured new optical images of the recently discovered young star at the heart of the Rosette Nebula that is ejecting a complex jet of material with knots and bow shocks. This is a rare example when early stages of star formation can be studied in detail using optical telescopes, because most young stars are embedded in very dense molecular clouds (ref: ApJL December 2003).
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15:03:2004 |
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4U 1820-30 |
Scientists at the Canadian Institute for Theoretical Astrophysics (CITA) and NASA made what may be the first observation of a carbon-fueled thermonuclear explosion on a neutron star. The three-hour event was far larger than most neutron-star flares, which last about 10 seconds. The explosion was observed with the Rossi X-ray Timing Explorer. Astronomers believe that such a long burst will provide new insights into the physics of neutron stars and thermonuclear explosions. The neutron star is part of a binary system called 4U 1820-30 (ref: NASA GSFC press release of February 23, 2004).
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08:03:2004 |
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SN 1993J |
A joint European/University of Hawaii team of astronomers has for the first time observed a stellar survivor’ to emerge from a double star system involving an exploded supernova. Using the Hubble Space Telescope and several ground-based observatories, astronomers discovered a massive companion star that must have been orbiting the second brightest known supernova SN 1993J at the time it exploded. The discovery is very important because it will allow astronomers watch what the remnant of a supernova does to its companion star (ref: ESA press release of January 8, 2004).
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08:03:2004 |
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