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By Daniel Fischer Every page present in Europe & the U.S.!
| Ahead | Awards 
The latest issue!
| A German companion - only available here! Current mission news: MGS (latest pictures!) + Cassini + Stardust |
It could be observed in the Marianas and Western Mexico, plus as a partial eclipse on several continents: a growing collection of reports, individual pictures and stories from the Philippines, from Tinian and from Mexico by Marlot, Schneider, Moskowitz, Arpin, Schmahl, Poitevin, Bruenjes, Ascencio and Fischer, another (undocumented) Mexican picture, a worldwide gallery (mostly partial phases but also two from Mexico on page 3), the view from San Francisco and coverage by the Saipan Tribune, The News (Mexico City), CNN, SkyNews, MSNBC, BBC, AP and SPIEGEL. Also the 'official' Homepage and advance coverage by CfA, ASP, S&T (other story), Science@NASA, CNN and SC ( earlier). Aussies expect chaos for December eclipse that hits a particularly remote part of the outback: ABC.
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Hot spots around SN 1987A: The birth of a Supernova Remnant as it happensIt's now 15 years since a massive star exploded in the Large Magellanic Cloud as Supernova 1987A - and since that day in February 1987 something new has happened virtually every year in its violent ruins. The current attraction: increasing interaction between the ejecta from the explosion and a pre-existing ring of matter around the dying star. Since 1995 and especially 1997 more and more luminous spots have appeared on that ring, in locations where matter has made contact with the old torus.The first spot was actually discovered in 1997, and for the next two years nothing much changed. But beginning in early 1999, new hot spots began appearing at various sites around the ring with every new HST observation: six in 1999, six more in 2000, and four more as of late 2001. The continuing trend of individual spots (rather than extended arcs) suggests that the hot spots mark the impact of ejecta with narrow, inward-pointing protrusions distributed around the visibly clumpy ring. Today there are hotspots scattered around almost the full circumference of the ring - and the bulk of the ejecta should be close now to colliding with the ring itself: Then »the real fireworks will begin,« says S. Lawrence of Hofstra University, »as the total amount of shocked, superheated gas suddenly skyrockets.« Roughly twice as many spots have appeared on the eastern side of the ring as compared to the west, and the eastern spots have tended to appear earlier: Apparently the ring is not centered exactly on the former star. |
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Aging star spews water molecules like a jerking garden hoseObservations of water masers around the old star W43A with the Very Long Baseline Array have resolved a remarkable pattern: These masers, emitting at 22 GHz, are strung out in two curved lines, moving in opposite directions from the star at about 150 km/s. The path of the jets is curved like a corkscrew, as whatever is squirting them out is slowly rotating or precessing. The water jets of W43A are probably just a few decades old and represent a very fleeting transitional stage in the development of this old star - an accretion disk seems to be involved, but it is unclear why this kind of star should still have one. The jet phenomenon, though, is the best explanation yet for the abundance of symmetrical planetary nebulae. (Imai & al., Nature of June 20, p. 829-31) |
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Betelgeuse resolved in the Far UV: a messy atmosphereThe first resolved far-ultraviolet image of the giant star Betelgeuse - or rather of its extended atmosphere - has been made with the STIS instrument on the Hubble Space Telescope: an asymmetric clumping of several hotspots, forming a »disk« three times are large as Betelgeuse's stellar diameter in visible light. The atmosphere is much larger and also more structured than previously thought - we still have a lot to learn about the atmospheres of giant stars. Previously the HST had observed Alpha Ori's atmosphere in the Near UV and already spotted time- variable hot spots, but the new pictures are much weirder still. |
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Filaments of glowing gas pervade the Milky WayIt's called WHAM, for Wisconsin H-Alpha Mapper, and this specialized spectrometer operating on Kitt Peak has indeed made a whanging discovery: The diffuse Warm Ionized Medium (WIM) which at about 10,000 Kelvins had already been known to be a significant component of the interstellar medium has a surprisingly rich spatial structure, full of filaments and knots. About 90 percent of the ionized hydrogen gas is found throughout the galaxy and not just in the vicinity of hot stars: some is in diffuse form, but some also forms distinct strands stretching up to 3000 light years above the Milky Way's disk. Somehow the O stars in the mid-plane of the galaxy are able to ionize gas over almost the entire Milky Way. |
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Lots of neutron stars, black hole candidates found in three elliptical galaxies: traces of a »wild youth«Thanks to the high angular resolution of the Chandra X-ray satellite hundreds of star-like sources have been identified in three elliptical galaxies: They are binary systems containing neutron stars and perhaps also stellar black holes. For these systems to form, the elliptical galaxies - nowadays pretty aged systems with faint, low-mass stars - must once have contained numerous massive stars: a clear indication that these galaxies did not always look like they do today.Interestingly the Chandra observations show that most of the X-ray-bright binary star systems are not scattered randomly among the stars in the elliptical galaxies: Most sit in globular star clusters. Their high abundance in dense tight systems of millions of stars suggests that the binary systems formed by the neutron stars or black holes capturing their companions, either by stealing a companion from another star or incorporating a lonely star - globular clusters may thus be termed the »single bars of the stellar world ...« |
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Quasars prefer the peripheries of galaxy clustersor the junction of two clusters that are just colliding: These surprising preferences of the quasar phenomenon for very specific interstellar environments have been derived from 60 »local« quasars with redshifts less than 0.3 at which the surrounding galaxy field can still be studied in some detail. A special mathematical technique called Voronoi tessellation was used to determine the boundaries of the galaxy clusters.A surprising picture emerged in which about two-thirds of the quasars were undoubtedly associated with galaxy clusters but unexpectedly with the peripheries of those: These galaxies with their extremely bright active nuclei prefer to form at the outskirts of clusters. A substantial minority lives within clusters, but these tend to have a second associated cluster - that is presumably colliding with the first. All this is pretty confusing at the moment but may mean that there is more than one mechanism to switch on a quasar. |
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The first detailled maps of the gas temperature in a small group of galaxieshave been obtained with the XMM-Newton X-ray satellite for the group around the galaxy NGC 4325 - and (again) tons of Dark Matter have been detected. Indirectly, that is: Simple physics say that one needs 10 times more than the visible mass (in all stars and gas detected at all wavelenghts combined) to hold the big cloud of hot gas together. The cloud - which has a diameter of 1.9 million light years and a temperature of 10 million Kelvins - is maintained by a balance between gravity and the pressure of the hot gas: Without enough mass, it would have dispersed long ago.What the Dark Matter - that makes up 90% of the group's total mass - actually consists of, the X-ray observations cannot say; it's probably some kind of undiscovered elementary particle, theorists presume. But the precise detection of so much Dark Matter in a small group of galaxies is important for our understanding of the Universe as a whole: galaxy groups are more representative of a »typical« galactic environment than the big galaxy clusters on which most studies of this kind had concentrated so far (see e.g. Update # 228 story 5 item 2). |
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100 meter asteroid missed Earth by 120,000 kmIt wouldn't have brought down mankind if it had hit, but an impact in a populated area or in an ocean would have caused a major disaster: On June 14 asteroid 2002 MN rushed past Earth at a distance of 120,000 km. Only tiny 1994 XM1 had come even closer (that is: as far as we know), but it was also much smaller (only a few meters) and would have burned up in the atmosphere. The same is true for several other close approachers that were recently added to the list. 2002 MN was thus "the largest object known to have come this close within decades," says Brian Marsden of the Minor Planet Center.A major issue of concern is that 2002 MN object was picked up only 3 days after the close approach, when it was detected by LINEAR. John Davies who calculated the orbit of the asteroid from the LINEAR data concludes that the asteroid came out of the Sun and was impossible for this automated system to see until one hour after its flyby of the Earth on the 14th. "If an asteroid were to approach close to an imaginary line joining the Earth and the Sun," he says, "it would never be visible in a night-time sky and would be quite impossible to discover with normal telescopes. Its arrival would come, literally, as a bolt from the blue." |
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First RHESSI results deepen solar flare mysteriesSince launched in February (see Update # 234 story 5) the Ramaty High Energy Solar Spectroscopic Imager has detected more than 100 larger flares on the Sun, plus countless microflares - and there is already one important result: a typical flare seems to begin with particles being accelerated in the Sun's magnetic field, and only some time later the solar atmosphere heats up. The observations show that just before a flaring region fills with hot gas, it emits hard X-rays associated with fast-moving electrons. The initial bursts are of ~20-keV photons, and even higher energy ~100-keV bursts reveal where energy is deposited by the electrons before spreading throughout the flare region.The X-rays from the base of the active region are "bremsstrahlung", caused by electrons slamming into the dense gases at the bottom of the corona. These electrons are thought to be accelerated by the collapse of stretched magnetic field lines high above the solar surface ("magnetic reconnection"). The impacts also heat the gas, which fills structures in the changing local magnetic field to yield the spectacular patterns seen with TRACE, and emits its own thermal X-rays as well. "We were surprised to see the X-rays coming from the base of the flaring region well before the initial brightening in the EUV," says Brian Dennis, RHESSI mission scientist: "We expected to see X-rays coming nearly simultaneously with the EUV brightening." |
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"New" NICMOS on Hubble better than everDuring a packed news conference in Albuquerque, NM, the first images taken with Hubble's NICMOS infrared instrument and its new cryogenic cooler have been released on June 5: After minor glitches in the weeks after the Servicing Mission (see Update # 235 story 2) the mechanical cooler is now operating perfectly and is keeping NICMOS at a steady 77 Kelvins - a much better operating temperature than the 61-63 K in the original configuration (with frozen nitrogen als the coolant). The tradeoff between dark current and quantum efficiency is now about perfect, making NICMOS 30 to 40 % more sensitive than before.But why did NASA put so much effort into building, testing and installing the cooler when groundbased large telescopes with adaptive optics (AO) can both reach fainter and see sharper than NICMOS? The answer is: it's the stability of the point spread function! With even the best AO currently available, about half of the starlight does not end up where one wants it but forms a fuzzy and fluctuating halo around every point source. Whenever one needs to do photometry in crowded fields (where those halos would overlap), e.g. in star forming regions or on the "surfaces" of galaxies, NICMOS will remain the better choice. The instrument will operate at least until the next servicing mission, currently planned for March 2004, and after that it might still be used intermittently in a so-called campaign mode (the cooler uses a lot of power). The fate of the HST beyond 2004 is still not decided, by the way, as the Cosmic Mirror has learned from a high-ranking NASA manager. The official policy remains to keep it operating until 2010 and then bring it back on a shuttle and put it into a museum. But intense discussions continue in the community whether one shouldn't field a final Servicing Mission around 2007, install a rocket stage for an eventual controlled reentry - and keep the famous and much improved telescope operating well beyond 2010. |
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Globular cluster torn apart by galactic gravityIt was already discovered in 2000, but now the picture has become even clearer: two well-defined tidal tails emerge from the sparse remote globular cluster Palomar 5. These tails stretch out symmetrically to both sides of the cluster in the direction of constant Galactic latitude and subtend an angle of 10 degrees on the sky. While typical globular clusters are massive, luminous concentrations of some hundred thousand stars, Palomar 5 by comparison looks faint and diffuse and contains only about ten thousand stars. This led astronomers to suspect that Palomar 5 might be a likely victim of the disruptive tides of the Milky Way.These "tides" arise because the Milky Way's gravitational pull is stronger on the cluster's near side than on the far side, thus tearing the cluster apart. However, the telltale debris from the disruption was difficult to find since it is hidden in a sea of foreground and background objects. Using data from the SDSS and a special filtering technique that picked out stars belonging to the cluster by their telltale colors, it was finaly possible to display the long and narrow tails in a convincing manner. From their shape the precise orbit of the cluster could be determined - and while it is still the only known case, there should be many more such clusters in the state of destruction out there while others are long gone. |
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ISS UpdateExpedition 5 is now on the ISS, while #4 made it back to Earth 2 days late - meanwhile NASA & ESA still can't agree on how to proceed with the project and the scientists working on the first real science plan for the ISS need more time as well: a joint NASA/ESA Statement, a NASA Press Release, Science@NASA of June 12 and 11, the Status and coverage of June 29: ST (other story). June 28: BBC. June 26: FT, ST. June 21: HC. June 20: NZ, Sp. June 19: SN, BBC, AFP, SC, ST. June 18: BBC, ST, Sp. June 17: ST. June 15: SN, ST (earlier), Sp. June 14: BBC, ST, Sp., NZ. |
June 13:
NYT.
June 12:
BBC,
ST,
Sp.,
Welt,
NZ.
June 11:
ST,
Sp.
June 10:
ST,
AFP,
Welt,
Sp.
June 9:
HC,
ST,
June 8:
SN,
SC,
Sp.
June 7:
ST.
June 6:
Sp.
June 5:
SN,
HC,
OS,
BBC,
ST,
June 4:
ST,
SN.
June 3:
NZ,
RP.
June 2:
SN,
SC,
ST.
The next STS mission will be delayed by several weeks because of of cracks in the fuel lines of one shuttle orbiter: FT, New Sci., SC, NYT, BBC, HC, SN, ST (earlier), NZ. The shuttle is a terrorist target: AW&ST. Mir, ISS visitor turns French minister - Claudie Haigner� has been appointed as deputy research minister in the new French Government: ESA News, BBC. |
15 new exoplanets include "Jupiter analog"15 new extrasolar planets have been announced, including one of the closests analogues to Jupiter yet found - 55 Cancri d has at least four times the mass of Jupiter but an orbit very similar to Jupiter: NASA Press Release, Science@NASA, NSU, SN, ScienceNews, NYT, WP, S&T, Ast., New Sci., BBC, AD, Wired, FT, CNN, Guard., SC, ST, Rtr. [Dsc.], AFP, Welt, RP, NZ.Another Jupiter-like exoplanet among many more discovered in Europe has a shorter orbit than the other one but a minimal mass of only 1.1 Jupiters: ESA Science News, SN, Ast., NYT, ST, CNN, SC, NZ. The tally now is 96 confirmed exoplanets from the radial velocity technique: SC. Still more candidates stem from transit observations: IAUC, SC. A star eclipsed by asteroids in a disk? KH 15D is being eclipsed in a way never seen before - not by another star or planet, but by dust grains, rocks and maybe even asteroids orbiting in a clumpy circumstellar disc: Wesleyan press kit, SN, S&T, Ast., New Sci., BBC, NYT, SC, ST, AP, NZ, Sp. Coolest Brown Dwarfs sometimes come in close pairsOf ten T dwarfs imaged by the HST, two were resolved into closely-separated binary brown dwarfs, with separations of 2 and 5 AU, and a third such system found with Keck I has a separation of 5 AU as well: Press Release.Three faint companions of bright stars discovered with new IR camera using AO on the old 100-inch telescope at the Mount Wilson Observatory: PSU Press Release, SC. Mars Odyssey deploys GRS boomA final major milestone in the activation of the new Mars orbiter has been achieved on June 4 with the deployment of the long boom of the gamma ray spectrometer: Mission Status, UA Press Release, ST, SC. Water discovery may shape future missions: AW&ST. The meaning of the discovery: PSRD, Economist.Giant Martian lake traced in Ma'adim Vallis, one of the biggest valleys on Mars: NASM Press Release, BBC, S&T, Ast., AP, APOD. CONTOUR launch delayed a few days after contamination on one of the spacecraft's solar panels has been discovered: Status Center, Homepage, delay news from KSC, CNN, ST. Earlier previews by CfA, NASA, ESA, AW&ST, New Sci., Dsc., NYT [HC], WP, CSM, AFP, BBC, SC, Guardian, Telegraph. |
A disk and a bipolar microjet of a young starhave been imaged with the HST near DL Tauri - and there are faint dark bands in the disk that could be lanes cleared by newborn planets (or just some shadows): GSFC Press Release [SN].A movie of Io in rotation with Adaptive Opticshas been generated at the Keck Observatory, both in the K- and the thermal L-Band, that shows dozens of volcanos glow: Keck Press Release, NSU.Galileo's final views of Io with many volcanoes, too: Plan. Soc., CNN, Sp. Pinpoint accuracy with the Proba cameraA new star tracker allowing a satellite to determine its orientation in space with an accuracy never seen before has proved its worth aboard ESA's Proba mission - this Project for On-Board Autonomy is carrying out a series of Earth observations with extreme accuracy, only possible because the satellite knows its own orientation in space so precisely: ESA News.Envisat has sent home its first Terabyte of Earth data, within just three months of its launch: ESA News. NOAA-M (NOAA-17) launchedIt's the third of five Polar Orbiting Environmental Satellites (POES) that will provide weather data from polar orbits over the next 10 years: GSFC Press Release and coverage by SN, SC, AFP, ST.Aqua instrument working fine now after a month of confusion: Status, SC. Early Aqua pictures: BBC, SC. Earlier: SpaceRef. EO-1 a success - the satellite has proven itself invaluable in its clarity and ability to more accurately identify objects on the Earth's surface: GSFC Press Release. Arizona fires seen from space: Pictures.
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All other historical issues can be found in the Archive.
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Compiled and written by Daniel Fischer
(send me a mail to [email protected]!), Skyweek
