The Cosmic Mirrorof News events across the Universe |
Archive | Index Ahead | Awards The latest issue! |
Space.com, SpaceViews! Current mission news: MGS (latest pictures!) + Cassini + Galileo |
use only the U.S. version of all pages for the time being!>>>
| Homepage, S&T article & Press Release, Astronomy, DLR, ASTRONET ESA Sci. News, Spacescience.com, BBC, ABC, MSNBC, EZ, Space.com |
Update # 168 of January 19th, 2000, at 20:15 UTC
Closer LMC, higher Hubble constant implied by "Red Clump" starsThe technique isn't widely used and somewhat controversial - but it seems to confirm the lingering doubts that the Large Magellanic Cloud is significantly closer and the Hubble constant thus larger than thought (see Updates # 133, story 2, and 148, story 4). Almost all cosmic distance indicators are calibrated with the LMC at some point, including the famous Cepheid stars. There is another class of stars, however, that is now being promoted as a major distance indicator, too - and those "Red Clump" stars have now also led to the conclusion that the LMC is about 12 percent closer to us than the widely accepted value.The ideal distance indicator would be a standard candle abundant enough to provide many examples within reach of parallax measurements (esp. by the Hipparcos satellite) and sufficiently bright to be seen out to local group galaxies. Red Clump stars precisely fit this description: They are the metal rich equivalent of the better known horizontal branch stars, and theoretical models predict that their absolute luminosity fairly weakly depends on their age and chemical composition. So named because they tend to "clump" together in a narrow range of color and brightness, Red Clump stars have masses similar to that of our Sun, but are older and more evolved, having used up all their hydrogen and are now converting helium into heavier elements in their cores. The most distinctive feature of Red Clumps, however, is their constancy: They give off a very consistent amount of light, so their absolute brightness is unvarying and predictable. Moreover, they are plentiful, especially where most needed by astronomers. While Cepheid variables are rare in the Milky Way and the LMC, the lower mass Red Clump stars are very common in both. Indeed, 15 percent of all the stars visible to the naked eye are Red Clumps. This makes the accurate calibration of their absolute brightness relatively easy and certain. The Hipparcos satellite measured parallaxes to 1000 Red Clump stars near the Sun and firmly fixed their intrinsic brightness with high precision. The Hipparcos measurements make Red Clump stars the best calibrated standard candles available to astronomers. |
| ||||||
The coolest Brown Dwarf ever: 500 degrees C!Infrared astronomers have identified the coolest body ever imaged outside of the solar system, a brown dwarf that lies only 19 light years from the Earth. The discovery was made during the Two Micron All Sky Survey (2MASS), a project whose goal is to image the entire sky at near-infrared wavelengths. The object had first raised suspicions because it had no optical counterpart; its spectrum then identified it as a Brown Dwarf. It sits in close proximity to a nearby triple star system called Gliese 570ABC, located in the constellation Libra, and it actually belongs to the system and can be called Gliese 570D. The 2MASS telescopes are in the midst of a 3-1/2-year survey of the entire sky. IPAC's processing of the 20 terabytes of raw survey data will create a publicly accessible catalog of 300 million stars and over one million galaxies. Already, 6% of the sky - more than 20 million objects - has been released to the public. . |
| ||||||
Complex organic molecules form quickly in spaceDo the crucial steps of chemical evolution - the formation of the precursors of living cells - take place on the surfaces of suitable planets, or can complex molecules form already in interstellar space? Ever since the Miller-Urey experiment in 1953, most scientists have held the view that life arose on the early Earth from simple inorganic molecules. With a suitable energy source (e.g. lightning) and a hospitable environment (e.g. oceans), complex organic molecules such as sugars and amino acids are thought to have originated from methane, hydrogen, and ammonia. These organic molecules then formed the basis of life as we have today.However, recent astronomical observations have discovered that complex organic molecules exist in stellar environments - and that they form from simpler molecules within just a few 1000's of years. Observations with the ISO infrared satellite have now demonstrated that small organic molecules with aliphatic structures evolve into large, complex aromatic molecules that rapidly: infrared spectra of very evolved red giants, proto-planetary nebulae and planetary nebulae were compared and showed the abundance of the aromates rising - and since only a few thousand years in evolutionary time separate these stars, their different infrared spectra give the most direct evidence of chemical synthesis in stars. Life could have travelled easily between Earth and Mars and vice versa, especially during the early stages of the solar system when impacts were much more frequent than today. Overall several billion meteorites have made the journey between the planets, often rapidly - and experiments have shown that primitive living cells could survive 'launch', interplanetary trip and 'landing'. This raises the possibility that "we are all Martians," because it is possible that conditions were sufficient for the origin of life earlier on Mars than on Earth... |
| ||||||
The first ground-based measurements of radio emission from interstellar molecules in the "terahertz waveband"A unique detector of astronomical radiation, developed at the Harvard-Smithsonian Center for Astrophysics (CfA), in Cambridge, Mass.,and tested at the Heinrich Hertz Submillimeter Telescope (HHT) on Mount Graham, Ariz., has made the first ground-based measurements of radio emission from interstellar molecules in the "terahertz waveband" -- a virtually unexplored part of the astronomical spectrum. The unique combination of the detector, the excellent high dry site and the accurate telescope were all necessary for this milestone in radioastronomy.The detector is a superconducting hot-electron bolometer (HEB), capable of detecting and amplifying very-high-frequency signals with very fine frequency resolution, so it can detect the spectral lines of interstellar molecules which emit radio signals at terahertz frequencies - the highest frequencies ever achieved with any radio receiver. The wavelengths corresponding to terahertz frequencies are smaller than one-third of a millimeter. The detection involved emission from molecules of carbon monoxide (CO) in the Kleinmann-Low Nebula in the Orion Molecular Cloud. The CO emission indicates that some of the gas in this star-forming cloud is some ten times hotter than average. But more important, these observations demonstrate that a "terahertz window on the universe" can be opened for ground-based astronomy. |
| ||||||
No more listening for the Mars Polar LanderThe Mars Polar Lander flight team has on Jan. 17th ended all attempts to communicate with the spacecraft. The final set of planned commands had been sent on Jan. 6 to place the spacecraft - if there is one - in UHF safe mode. Since then the Mars Global Surveyor listened for the lander around the clock. These attempts have ended on the 17th, concluding all to recover the spacecraft. The Mars Global Surveyor continues to perform special targeted observations of the Mars Polar Lander landing site in hopes of imaging the lander or its parachute. No evidence of the spacecraft has been sighted so far and these attempts will continue through early February. The team has started in depth analysis of terrain hazards within the landing footprint in support of the JPL Mars Polar Lander/Deep Space 2 Failure Review Board. |
|
NEAR begins to image ErosOn Jan. 12th the first picture of the asteroid in over a year was taken by the NEAR spacecraft, one month before the 2nd attempt to enter into an orbit: first picture and statement; Space Daily, SpaceViews, SpaceRef, MSNBC, more S.D. stories.Deep Space 1 points antenna back to Earth, transmits data - all without the (failed) startracker: Space Daily. Huge eruption by Io volcano just when Galileo flew byIn November 1999, astronomers photographed a large volcanic eruption on Io just as Galileo was there: Keck AO and IRTF pictures, plus details from LLNL, SpaceRef and Spacescience.com.Some results from the airborne Leonids campaignof 1999 are now on display at the MAC'99 site, including unusual aeronomical images. Meteor explosion brightens skies near Alaska, shaking houses and providing a dramatic light show: Space.com. DoD satellite saw it, too: Info.Tile problem could delay shuttle Endeavour launchThe first shuttle flight of 2000 might be delayed after new concerns were raised Tuesday with the workmanship on NASA's $2 billion spaceplanes: KSC Press Release and Space.com, Fla. Today, Spaceflight Now, SpaceViews stories. More mission pages from JPL and Quest.China to participate in the ISS?The Chinese government is considering plans to participate in the International Space Station project, a government-run newspaper claims: People Daily article, Space Daily, SpaceViews coverage.Huge X-ray telescope proposed for the ISS - the Energetic X-ray Imaging Survey Telescope (EXIST): paper by Grindlay & al.. |
CGRO's fate all but sealed?Sources familiar with the Compton Gamma Ray Observatory (CGRO) project say that a gyro failure on the telescope last month has forced NASA to study whether the orbiting observatory should be brought down now before another gyro failure renders the telescope uncontrollable: CNN, SpaceRef, UPI, SpaceViews, BBC, Space.com.Amateur photographs XMM in orbit, using a homebuilt 45 cm Newtonian telescope. Meanwhile the lengthy calibration of the satellite's optical and X-ray cameras has commenced - all operations are proceding normally and the first pictures will be released to the public in the next few weeks: the picture, ESA Science News, a BBC story. Hubble has returned to observing - calibration and testing will continue into early March, but science observations began last week and will continue in concert with the check-out operations: Space.com. Budget boost for NASA expected for FY 2001Clinton will ask Congress next month for a healthy boost in NASA's budget for 2001, and the agency's space science office in particular can look forward to White House support for more money: Space.com.Bizarre ice blocks rain on Spain...... and some believe it could be debris from a comet - which would raise far more questions than it would solve (why pure water, why didn't it burn up, why only Spain? :-): Space.com, BBC, CNN, InfoBeat, CENAP News stories.
|
Compiled and written by Daniel Fischer
