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Дата: 13 апреля 1998 (1998-04-13) От: Alexander Bondugin Тема: Hubble Finds That Even Massive Stars Just Fade Away Привет всем! Вот, свалилось из Internet... FOR RELEASE: 9:00 a.m. (EDT) April 9, 1998 CONTACT: Ray Villard Space Telescope Science Institute, Baltimore, MD (Phone: 410-338-4514) PRESS RELEASE NO.: STScI-PR98-16 HUBBLE FINDS THAT EVEN MASSIVE STARS JUST FADE AWAY Pinpointing the rapidly fading ember of a recently burned out star, NASA's Hubble Space Telescope is giving astronomers a better estimate on just how big a star can be before it ultimately explodes as a supernova. Based on Hubble's detection of a rare, young white dwarf star, astronomers conclude that its progenitor was a whopping 7.6 times the mass of our Sun. Previously, astronomers had estimated that stars anywhere from 6 to 10 solar masses would not just quietly fade away as white dwarfs, but abruptly self-destruct in torrential explosions. This new lower limit will help astronomers refine theories of how galaxies developed in the early universe, determine the rate at which supernovae enrich interstellar space with heavy elements for building new generations of stars and planets, and estimate the number of neutron stars in space (neutron stars are the crushed stellar cores resulting from supernovae). Rebecca Elson and Steinn Sigurdsson of Cambridge University, and co-investigators, discovered the ultra-hot white dwarf during a search in archival Hubble Wide Field Planetary Camera 2 pictures of the young star cluster NGC 1818, located 164,000 light-years away in the Large Magellanic Cloud -- a satellite galaxy of our Milky Way. The trick was to identify a newly formed white dwarf that was still exceptionally hot and bright immediately after the burnout and collapse of its progenitor star. Such a dwarf would be so "young" - relative to older fainter dwarfs in the cluster -- it would allow a direct link back to the most massive stars now present in the cluster. That's because the most massive stars are the shortest lived, and so are first to burnout as white dwarfs. Because the star cluster NGC 1818 is ten times larger than those found closer to us within our own galaxy, chances were far better for catching the young dwarf before it swiftly dimmed on its way to the "graveyard" of faint dwarfs. Also, the cluster is only about 40 million years old, and so still contains massive stars. Hubble is ideally suited for hunting for white dwarfs so far away because its exquisite resolution can pinpoint them among the cluster's crowded stellar population, and can easily detect the blue light from the sizzling 50,000 degree Fahrenheit surface temperature of the young dwarf. Once the candidate star was identified, a spectrum of the star obtained at the Anglo-Australian Observatory. "Our spectrum indicates that it is neither a foreground nor background object, and detailed modeling is underway to understand its exact evolutionary state," says Elson. The results will be reported in the Astrophysical Journal Letters. -- end -- The Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract with the Goddard Space Flight Center, Greenbelt, MD. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. EDITOR'S NOTE: Images to accompany this release are available electronically via the World Wide Web at: http://oposite.stsci.edu/pubinfo/1998/16 and via links in http://oposite.stsci.edu/pubinfo/latest.html or http://oposite.stsci.edu/pubinfo/pictures.html. GIF and JPEG images are available via anonymous ftp to oposite.stsci.edu in /pubinfo/gif/9816.gif and /pubinfo/jpeg/9816.jpg. ****************************** FOR RELEASE: 9:00 a.m. (EDT) April 9, 1998 PHOTO NO.: STScI-PRC98-16 HOT WHITE DWARF SHINES IN YOUNG STAR CLUSTER A dazzling "jewel-box" collection of over 20,000 stars can be seen in crystal clarity in this NASA Hubble Space Telescope image, taken with the Wide Field and Planetary Camera 2. The young (40 million year old) cluster, called NGC 1818, is 164,000 light-years away in the Large Magellanic Cloud (LMC), a satellite galaxy of our Milky Way. The LMC, a site of vigorous current star formation, is an ideal nearby laboratory for studying stellar evolution. The circled star is a young white dwarf star, which has only very recently formed following the burnout of a red giant. Based on this observation astronomers conclude that the red giant progenitor star was 7.6 times the mass of our Sun. Previously, astronomers have estimated that stars anywhere from 6 to 10 solar masses would not just quietly fade away as white dwarfs but abruptly self-destruct in torrential explosions. Hubble can easily resolve the star in the crowded cluster, and detect its intense blue-white glow from a sizzling surface temperature of 50,000 degrees Fahrenheit. IMAGE DATA Date taken: December 1995 Wavelength: natural color reconstruction from three filters (I,B,U) Field of view: 100 light-years, 2.2 arc minutes TARGET DATA Name: NGC 1818 Distance: 164,000 light-years Constellation: Dorado Age: 40 million years Class: Rich star cluster Apparent magnitude: 9.7 Apparent diameter: 7 arc minutes Credit: Rebecca Elson and Richard Sword, Cambridge UK, and NASA (Original WFPC2 image courtesy J. Westphal, Caltech) Image files are available electronically via the World Wide Web at: http://oposite.stsci.edu/pubinfo/1998/16 and via links in http://oposite.stsci.edu/pubinfo/latest.html or http://oposite.stsci.edu/pubinfo/pictures.html. GIF and JPEG images are available via anonymous ftp to oposite.stsci.edu in /pubinfo/gif/9816.gif and /pubinfo/jpeg/9816.jpg. Hа сегодня все, пока! =SANA=

Дата: 13 апреля 1998 (1998-04-13) От: Alexander Bondugin Тема: Full Data Sets From Galileo's First Six Orbits Now Available Привет всем! Вот, свалилось из Internet... Galileo Solid State Imaging Full Data Releases ALL IMAGES obtained by the Galileo Solid State Imaging (SSI) system during the spacecraft's first six orbits (G1, G2, C3, E4, E6) of Jupiter are now validated and available. Images and data obtained by NASA/JPL's Galileo mission have been available on an ongoing basis during the spacecraft's journey through the Jovian system in order to share with the public the excitement of exploration and new discoveries being made via the NASA/JPL Galileo spacecraft. Galileo scientists have a one year period set aside for the process of calibrating and validating the data. The full digital images necessary for scientific analysis are released within one year of receipt of an orbit's last data. * IMAGE PRODUCTS from the ongoing public releases are available now in multiple formats (including tiff, gif, pict, jpeg). * ALL IMAGES from the first six orbits (G1, G2, C3, E4, and E6) are merged and validated and available via the Planetary Data System. * Nominal Mission (6/96 - 12/97) Release Schedule for validated data sets * ALL Galileo Cruise Phase (10/89 - 12/95) Data ALL IMAGING DATA from Orbits 1 through 6 is available via the Planetary Data System (PDS) Imaging Node For Galileo SSI data, go to URL: http://www-pdsimage.jpl.nasa.gov/PDS/public/Atlas/Atlas.html and select the option: "Galileo SSI REDRs of Earth and the Moon, Venus, Gaspra, Ida, and Jupiter and its satellites " The PDS homepage is: http://www-pdsimage.jpl.nasa.gov/PDS/ The PDS offers a simple query interface to access all fully released SSI data. It allows the user to search by various parameters such as target name, spacecraft clock, latitude/longitude, filter, phase angle, exposure, gain, and compression ratio. PDS will continue to expand and improve this interface which will eventually include a format to select data via a map interface. To accomodate the various needs of the scientific community, the archived files are raw data files which merge the multiple downlinks of data to provide the best final version of an image. Supporting data such as calibration files are also available. Such files include dark currents, radiometric calibrations, blemishes, hot pixels, etc.. Galileo Primary Mission (6/96-12/97) Solid State Imaging Orbital Data Sets Public Release Schedule Orbit 1 (G1) September 06, 1997 Orbit 2 (G2) November 04, 1997 Orbit 3 (C3) December 19, 1997 Orbit 4 (E4) February 20, 1998 Orbit 6 (E6) April 05, 1998 Orbit 7 (G7) May 07, 1998 Orbit 8 (G8) June 25, 1998 Orbit 9 (C9) September 17, 1998 Orbit 10 (C10) November 06, 1998 Orbit 11 (E11) & GEMSchedules will be posted when available. NASA/JPL's Galileo Project gratefully acknowledges the collaborative efforts of NASA's Planetary PhotoJournal and the Planetary Data System in making Galileo mission images and data available to the public and scientific communities. Hа сегодня все, пока! =SANA=

Дата: 13 апреля 1998 (1998-04-13) От: Alexander Bondugin Тема: Sky & Telescope News Bulletin - April 10, 1998 Привет всем! Вот, свалилось из Internet... SKY & TELESCOPE'S WEEKLY NEWS BULLETIN APRIL 10, 1998 FACE OFF ON MARS Scientists with NASA's Mars Global Surveyor program have finally settled a longstanding question about the nature of unusual topographic features in the red planet's Cydonia region. Noisy, low-resolution Viking images from 1976 showed what looked like a giant mound carved into the shape of a human face. But new, razor-sharp views from Surveyor, released on April 6th, show a complex, hilly formation that has been eroded by Martian winds, frost, and perhaps surface water. The "Face on Mars" was illusory, though news reports from earlier this week suggest that some fanatics refuse to give up on the idea that the alleged face is manmade -- made by little green men, that is. SIZZLIN' SUNSPOTS There may be no face on Mars, but there sure are a lot of spots on the Sun's face. At least four major sunspot groups appeared this week alone. Patrick McIntosh of Heliosynoptics in Boulder, Colorado, says that if you look at the Sun's southern hemisphere, you'll think it's solar maximum. The northern hemisphere looks more typical of solar minimum, though there are a couple of small spot groups there. In reality, our daytime star has passed the overall minimum of magnetic activity and is now climbing steeply toward the maximum of its 11-year cycle, anticipated to occur around the year 2001. HELLO, TRACE As the Sun's activity increases, it will come under the scrutiny of a new NASA satellite. The Transition Region and Coronal Explorer (TRACE) was lofted into orbit on April 1st by a winged Pegasus rocket dropped from a Lockheed L-1011 aircraft. It will explore the magnetic structures responsible for carrying energy from the Sun's photosphere, or visible surface, through the thin chromosphere and out into the wispy corona. GOOD-BYE, ISO While the TRACE mission has just begun, that of another astronomy satellite has come to an end. Europe's Infrared Space Observatory (ISO) ran out of liquid-helium coolant for its heat-sensitive detectors on April 7th. Originally expected to last only 18 months, ISO has been in orbit for more than two years. Highlights of its 26,000 observations include images and spectra of the star-forming regions in Orion, a survey of interstellar dust clouds, and studies of the Small Magellanic Cloud and M33, the large spiral galaxy in Triangulum. SURF'S UP IN ORION! Although ISO has ceased taking data, astronomers are still poring over results gathered earlier. In Astrophysical Journal Letters this month, a team led by Martin Harwit of Cornell University announces their discovery of a massive concentration of water vapor in M42, the Orion Nebula. Strong emissions from steam observed with ISO's long-wavelength spectrometer imply that there's enough water in M42 to fill Earth's oceans 60 times over every day! The steam forms in chemical reactions among the nebula's abundant hydrogen and oxygen molecules, energized by the ultraviolet light of hot, young stars. GALILEO'S GYRATIONS There's yet another spacecraft in the news this week. The Galileo Jupiter orbiter continues its extended mission, the focus of which is the enigmatic ice moon Europa. The last Europa flyby was on March 29th, and the next comes on May 31st. Flight controllers are practicing using stellar navigation to orient the spacecraft properly, because one of its stabilizing gyros is showing signs of radiation damage from the harsh Jovian environment. URANUS' NEW MOONS RECOVERED Now that the distant planet Uranus has emerged from the solar glare, astronomers have recovered the two tiny moons discovered last September. Curiously, one was a half arcminute off its predicted position, while the other was fully 3 arcminutes off. As reported in IAU Circulars 6869 and 6870, the new observations indicate that the moon known as S/1997 U1 orbits Uranus in a more circular path than originally thought, while its counterpart, S/1997 U2 moves in a much more elongated orbit. With the orbits now well defined, it has been possible to confirm that a tentative report of a possible Uranian satellite in 1984 was, in fact, a prediscovery observation of S/1997 U1. THIS WEEK'S "SKY AT A GLANCE" Some daily events in the changing sky, from the editors of SKY & TELESCOPE. APRIL 12 -- SUNDAY * Well to the upper right of the Moon tonight is the blue-white star Spica. About twice as far to the Moon's upper left is brighter Arcturus, pale yellow-orange. APRIL 13 -- MONDAY * Saturn is in conjunction with the Sun. APRIL 14 -- TUESDAY * Some doorstep astronomy: Face southwest right after dark; the brilliant star rather low is Sirius. To its right, by about two fist-widths at arm's length, is the horizontal row of three fainter stars forming Orion's Belt. * The red variable star T Camelopardalis should be near maximum light (8th magnitude) around this date. APRIL 15 -- WEDNESDAY * The orange star Antares rises to the lower right of the waning gibbous Moon around 11 tonight. APRIL 16 -- THURSDAY * As dawn begins to break on Friday morning, Venus appears only 1/3 degree from the 4th-magnitude orange star Lambda Aquarii. Have a look with binoculars. APRIL 17 -- FRIDAY * Some doorstep astronomy: Face due south soon after dark and look high up. The brightest star there is Regulus in the constellation Leo. APRIL 18 -- SATURDAY * This morning and tomorrow morning, Jupiter is only 0.1 degree from the 4.4-magnitude orange star Phi Aquarii. ============================ THIS WEEK'S PLANET ROUNDUP ============================ MERCURY, MARS, and SATURN are hidden in the glare of the Sun. VENUS shines low in the east-southeast during dawn. JUPITER is to the lower left of Venus, closing in on it daily. They're 9 degrees apart on the morning of April 12th, and 4 degrees apart on the 18th. (By comparison, your fist held at arm's length appears about 10 degrees wide.) URANUS and NEPTUNE, magnitudes 6 and 8, respectively, are in Capricornus low in the southeast just before dawn. PLUTO, magnitude 13.8, is near the Ophiuchus-Scorpius border. It's well up in the southeast by about 1 a.m. (All descriptions that relate to the horizon or zenith are written for the world's midnorthern latitudes. Descriptions that also depend on longitude are for North America. Eastern Daylight Time, EDT, equals Universal Time minus 4 hours.) Copyright 1998 Sky Publishing Corporation. S&T's Weekly News Bulletin and Sky at a Glance stargazing calendar are provided as a service to the astronomical community by the editors of SKY & TELESCOPE magazine. Widespread electronic distribution is encouraged as long as these paragraphs are included. But the text of the bulletin and calendar may not be published in any other form without permission from Sky Publishing (contact permissions@skypub.com or phone 617-864-7360). Illustrated versions, including active links to related Internet resources, are available via SKY Online on the World Wide Web at http://www.skypub.com/. In response to numerous requests, and in cooperation with the Astronomical League and the American Association of Amateur Astronomers, S&T's Weekly New Bulletin and Sky at a Glance are available via electronic mailing list too. For a free subscription, send e-mail to skyline@gs1.revnet.com and put the word "join" on the first line of the body of the message. To unsubscribe, send e-mail to skyline@gs1.revnet.com and put the word "unjoin" on the first line of the body of the message. SKY & TELESCOPE, the Essential Magazine of Astronomy, is read by more than 200,000 enthusiasts each month. It is available on newsstands worldwide. For subscription information, or for a free copy of our catalog of fine astronomy books and products, please contact Sky Publishing Corp., P.O. Box 9111, Belmont, MA 02178-9111, U.S.A. Phone: 800-253-0245 (U.S. and Canada); 617-864-7360 (International). Fax: 617-864-6117. E-mail: custserv@skypub.com. SKY Online: http://www.skypub.com/. Clear skies! Hа сегодня все, пока! =SANA=

Дата: 13 апреля 1998 (1998-04-13) От: Alexander Bondugin Тема: NASA Finds Problems In EOSDIS Flight Operations Software Development Привет всем! Вот, свалилось из Internet... David E. Steitz Headquarters, Washington, DC April 10, 1998 (Phone: 202/358-1730) Allen Kenitzer Goddard Space Flight Center, Greenbelt, MD (Phone: 301/286-2806) RELEASE: 98-60 NASA FINDS PROBLEMS IN EOSDIS FLIGHT OPERATIONS SOFTWARE DEVELOPMENT NASA has found software performance problems with ground system software required to control, monitor and schedule science activities on the Earth Observing System (EOS) series of spacecraft. Officials believe these problems will delay the software which will impact the launch date for the Earth Observing Spacecraft AM-1. The launch, originally planned for late June 1998, from Vandenberg Air Force Base, CA, will be delayed at least until the end of the year. The Ground Control Software, called the "Flight Operations Segment" (FOS) software, is part of the Earth Observing System Data and Information System (EOSDIS), the ground system responsible for spacecraft control, data acquisition, and science information processing and distribution for NASA's Earth Science enterprise, including the EOS flight missions. The problem is with the EOSDIS control center system FOS software that supports the command and control of spacecraft and instruments, the monitoring of spacecraft and instrument health and safety, the planning and scheduling of instrument operations, and the analysis of spacecraft trends and anomalies. What was supposed to have been the final version of the software was delivered to NASA by Lockheed Martin on March 31, to support integrated simulations with the EOS AM-1 spacecraft. Testing of this software delivery revealed significant performance problems. Program managers expect it to take several weeks to clearly understand whether correcting the current software or taking other measures is the best approach. "We're concurrently looking at commercial off-the-shelf technology that was not available when this software system initially was designed," said Arthur "Rick" Obenschain, project manager for EOSDIS at NASA's Goddard Space Flight Center, Greenbelt, MD. "If for some reason the current software problems cannot be fixed, we have a backup plan." Prior to the March 31 delivery, there were three previous incremental deliveries of the software in August 1997, December 1997 and February 1998. Previous versions of the software successfully demonstrated real-time commanding functions with the AM-1 spacecraft. In the new version, however, a number of problems identified in the previous software deliveries were not corrected as expected, and significant problems were found in the new capabilities. Problems include unacceptable response time in developing spacecraft schedules, poor performance in analyzing spacecraft status and trends from telemetry data, and improper implementation of decision rules in the control language used by the flight team to automate operations. Government/contractor teams have been formed to evaluate options for correcting these problems to minimize impact on the AM-1 launch. A recovery plan is being developed and will be reviewed during the last week of April. The FOS is being developed by Lockheed Martin under subcontract to Raytheon Information Systems Company under the EOSDIS Core System contract. The Flight Operations Segment of the EOSDIS software has cost $27.5 million as of February 1998. THE EOSDIS and EOS AM-1 are part of NASA's Earth Science enterprise, a long-term research program designed to study Earth's land, oceans, atmosphere, ice and life as a total integrated system. Goddard manages the development of EOSDIS and EOS AM-1 for NASA's Office of Earth Science, Washington, DC. -end- Hа сегодня все, пока! =SANA=

Дата: 13 апреля 1998 (1998-04-13) От: Alexander Bondugin Тема: Mars Global Surveyor Update - April 10, 1998 Привет всем! Вот, свалилось из Internet... MEDIA RELATIONS OFFICE JET PROPULSION LABORATORY CALIFORNIA INSTITUTE OF TECHNOLOGY NATIONAL AERONAUTICS AND SPACE ADMINISTRATION PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011 http://www.jpl.nasa.gov Mars Global Surveyor Mission Status April 10, 1998 The Mars Global Surveyor operations team is gearing up to begin imaging a second set of specifically targeted geologic features on Mars, after completing the first set of images last week and successfully capturing the so-called "Face on Mars." At the direction of NASA Administrator Daniel Goldin, the flight team has developed a schedule of new targets. On Tuesday, April 14, Global Surveyor will image a second portion of the Cydonia region known as "The City." This area of Cydonia contains geological features that have been referred to as "mounds," a "city square," "pyramids" and "the fortress." The spacecraft's high-resolution camera will use the "city square" portion of this geologic formation as the target point. The image will be posted on JPL's Mars news site at http://www.jpl.nasa.gov/marsnews, on the Mars Global Surveyor project home page at http://mars.jpl.nasa.gov, and on NASA's Planetary Photojournal site at http://photojournal.jpl.nasa.gov as soon as it is available. This is expected to be by about mid- evening Pacific time on Tuesday, April 14. Last week's attempts to image the landing sites of the Viking 1, Viking 2 and Mars Pathfinder landers were unsuccessful. Global Surveyor will make new attempts to image the Viking sites on two consecutive orbits on Sunday, April 12. On Monday, April 13, the spacecraft will image the Mars Pathfinder landing site, using refined coordinates obtained during the first attempt. Winter weather in the northern hemisphere of Mars was a significant factor in preventing a view of the landing sites during the first series of attempts. The site of the Viking Lander 1 in Chryse Planitia, for instance, was covered with a thick cloud layer, which reduced but did not eliminate surface visibility. However, data showed that the spacecraft's pointing was off just enough to miss that target. The spacecraft was able to target the Viking 2 lander site in Utopia Planitia, which is farther north and on the other side of Mars from Viking 1. However, this area was heavily overcast with clouds and haze which reduced surface visibility by 70 to 80 percent and rendered the image unusable. The spacecraft missed the Mars Pathfinder site due to the inaccuracy of landing site coordinates. The project team estimates that Global Surveyor has about a 30 to 50 percent of imaging each target on a given attempt, due to navigation uncertainties and spacecraft performance. A third and final set of high-resolution imaging of the Viking, Pathfinder and Cydonia regions will be attempted on April 21-23. ##### Hа сегодня все, пока! =SANA=

Дата: 13 апреля 1998 (1998-04-13) От: Alexander Bondugin Тема: Mars Global Surveyor Update #2 - April 10, 1998 Привет всем! Вот, свалилось из Internet...