The database contains references to the papers, data files and links to the Internet resources related to measurements and calculations of the optical constants in the wavelength interval from X-rays to radio domain. ... References to some useful books and reviews on the subject (e.g. the classical handbooks edited by E.D.Palik) and links to Internet collections of optical constants and personal WWW pages with related software were also placed in the database. You have arrived at our welcome page. ...

... Tonight's Sky . ... The Magazine . ... Observing . ... The double star 54 Leonis, spiral galaxy NGC 3198, and emission nebula NGC 3199 . ... Astronomy for Kids . ... Observing springtime deep-sky objects with a large telescope . ... Bright planets meet at dusk . ... Astronomy magazine subscribers can read the full article for free. ... Get instant access to subscriber content on Astronomy.com! ... Receive news, sky-event information, observing tips, and more from Astronomy's weekly email newsletter....

... The Sun is powered by nuclear fusion: hydrogen `burns' to form helium, releasing energy . ... At an age of ~10 billion years (slightly over twice its present age), the Sun will exhaust the fuel available in its core. ... Pressure overwhelms gravity, and over a period of a few hundred thousand years, the Sun evolves into a `red giant' . ... Red giants have lifetimes of less than 100 million years. The temperature in the red giant core increases to 100 million degrees . ... The Ring Nebula . ...

Next: Radial velocity of the Up: Optical spectrum of IRAS04296 Previous: Observations and spectra reduction . ... However, molecular emission features are only very rarely observed in the optical spectra of PPNe. ... On the other hand, it is well known that cometary nuclei spectra show prominent Swan band emission. In both spectra of IRAS04296 we have discovered strong emission in the (0;0) and (0;1) bands of the Swan system of the molecule. ... Now consider the case of IRAS04296. ...

... This type of analysis requires careful intensity calibration of the Mopra observations. ... Figure 1: Comparison of SEST and Mopra data before and after calibration of the Mopra data. (a) SEST corrected antenna temperature (T A *) plotted with Mopra peak antenna temperature before calibration (Q T ). ... The calibrated Mopra observations can then be placed on the SEST antenna temperature scale using the linear fit from Figure 1b. This relationship is . T A *(SEST) = (1.62 ? 0.06)T A '(Mopra). ...

... The formation of spectral disturbances of Cosmic Background Radiation (CBR) during the period of hydrogen recombination at redshift is considered. Special attention is paid to the decimeter and meter wavelength band. ... In this paper we will return to the question on the spectral lines caused by recombination of hydrogen discussed by Dubrovich (1975) , in the longer wavelength part of spectrum of the CBR. ... A synthesis of recombination radiolines spectra is divided into several stages. ...

... Stellar Evolution is driven entirely by the never ending battle between Pressure and Gravity . As imbalances are reached, the star is driven to find a new Energy source. ... Pressure and gravitational forces are equal, the star is stable and its core is sufficiently hot to fuse Hydrogen into Helium More about main sequence stars . ... The luminosity generated by the core fusion of Helium into Carbon is far greater than the shell luminosity associated with the fusion of Hydrogen into Helium. ...

... Initially SAI Supernova Catalogue was presented in the form of filebased system. ... The current version of SAI Supernova Catalogue presents data on supernovae together with data on their parent galaxies. ... The main source of data for the galaxies was LEDA database. ... In some cases our data were compared with the ones from the Asiago Supernova Catalogue and from List of Supernovae at Harvard-Smithsonian Center for Astrophysics, but the compilation of our Catalogue is carried out independently. ...

... This is a preliminary summary of the event on November 24, 1996, considered during the INTERBALL Workshop in Kiljavanranta, Finland, February 1998. ... Pronounced plasma sheet thinning (Bz decrease) . ... Particle burst observed inside the Polar Cap and in tail lobes . A short burst of particles detected by the Auroral Probe particle detectors during the Polar Cap crossing at 21:45 UT, almost simultaneously with the Tail Probe detectors registration of the particle burst inside the North Lobe. ...

Hot subdwarfs are hots stars with masses somewhat less than that of the Sun. ... They are known as sdB stars because their spectra are dominated by hydrogen lines. ... Normally, a red giant will switch on core helium burning without losingthe layers of hydrogen around the helium core. sdOB stars are related to sdB stars, possibly being the sdB stars which have completed core helium burning and are evolving to become white dwarfs. ... Such stars are known as PG1159 stars and DO white dwarfs. ...

... Spiral disks are loose conglomerations of billions of stars and diffuse gas all gravitationally orbiting a galaxy center. ... What used to be considered a hole in the sky is now known to astronomers as a dark molecular cloud. Here, a high concentration of dust and molecular gas absorb practically all the visible light emitted from background stars. ... A rare type of galaxy known as a Polar Ring, NGC 4650A is composed of an old central group of stars and a young ring of stars rotating farther out. ...

... Using the uvby -photometry and proper motion data for about 5500 F stars within 80 pc from the Sun, we have studied velocity ellipsoid parameters and obtained the following results. 1) The sizw of all wllipsoid semiaxes increase systematically for groups of stars with the decrease of both temperature (at constant metallicity) and metallicity (at constant temperature). ... As a result, each of the three parameters - temperature, metallicity and velocity dispersion - is an age indicator. ...

The Cosmic Microwave Background Radiation Temperature Work in groups of 2-4. ... Due 1999 April 15 In this laboratory exercise, you will use the radio telescope on the roof of Science B to measure the intensity of the Cosmic Microwave Background Radiation (CMBR). ... The output of the telescope when pointing at the sky will then be 2 Tsys = Trec + Tsky : The temperature of the sky can in principle arise from two sources, radiation from the atmosphere and radiation from outer space (the CMBR). ...

Next: Parameters of the starburst Up: The Model Previous: Initial parameters of compact . ... If the rate of accretion from one star to another is sufficiently high (e.g., the mass transfer occurs on a timescale a few times shorter than the thermal Kelvin-Helmholz time for the normal companion) or the compact object is engulfed by a giant companion, the common envelope (CE) stage of the binary evolution can set in (see Paczynski 1976; van den Heuvel 1983). ...

STEP INTO THE BLUE - MEADE INSTRUMENTS PRODUCT GUIDE . ... Telescopes . LX850 Series . ... Superb optical performance coupled with time proven computerized pointing and tracking has made the LX200 ACF series a best-seller in the high-performance telescope class. ... Meade's revolutionary LS LightSwitchтДв series of telescopes use advanced technologies to do what no other consumer telescopes have done before: take all the hassle out of using a telescope. ... Support . ... Become a Meade Dealer . ...

Chair of solid state physics . ... The Physics of Phonons . ... In the first part of the course “The Physics of Phonons” the dynamics of atoms in one- and three- dimensional crystalline lattices is considered in detail. The quasiparticle conception in solids, taking phonons as an example, is discussed; creation and annihilation operators of phonons, main properties of acoustic and optical phonons dispersion laws, density of phonon states. ... Crystalline state. ... Acoustic and optical phonons. ...

Next: Post Operational HST Science Instrument Archives . Up: Archiving . ... In these days of CD, DVD, HD-ROM, NFR, and myriad other acronyms, a tried and true storage technology came out a winner for HST data. ... We will present the methods used to define requirements, evaluate technology solutions, why we selected Magneto Optical as our current storage solution, and why we continue to watch the storage industry for new products with an eye towards support of NGST. ...

... There are many theories on what will destroy planet Earth, such as nuclear annihilation, global warming or the Sun becoming a red giant. ... It was founded by the board of directors of the magazine `Bulletin of the Atomic Scientists' to draw the public's attention to the nuclear threat, midnight being the time when Doomsday will occur. ... The board has said that climate change has now become the second biggest threat to the existence of the Earth after global nuclear war. ...

... part 1 | ... The Basic Stages in Earth's Pre-geological Development . ... After fragments of the Vortex sleeves separated, whirlwinds of second and third orders ("NC" - new micro-vortex) were generated- future planet cores and their satellites - all of them developing independently, governed by the common laws of development of cosmogenic vortexes. ... Our planet's core today is comprised of considerably deteriorated cosmogenic vortex; consequently, the Earth has a moderated magnetic field. ...

... GSAOI Home . ... Science . ... Despite vast increase in our understanding of the evolutionary nature of planetary nebulae (PNe) during the last three decades, a central question remains: where is the missing mass? Theoretical evolutionary tracks predict that all stars with masses in the range 1.4-8 M Sun should become PNe. ... Clearly, much of the mass of the planetary nebula shell must remain un-ionized, and much of it may be in molecular form. ... The Magellanic Cloud PNe are ideal for this. ...