... 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. ...

Observation and modelling of main sequence star chromospheres. ... We compare our calculations to recent high res­ olution observations for selected stars in a narrow spectral range ((R­I) џ =0.875\Sigma0.05); we show that Hff line profiles behave as expected, with a tight correlation be­ tween the line width and equivalent width. ... We show that the hydrogen series dominate the radiative cooling in the spectral lines (form 40% to 90%) for Hff emission line stars. ...

Planetary nebulae are the remnants of low-to-middle mass stars. ... These so-called post-AGB stars are in an intermediate stage of evolution between the AGB and planetary nebulae. ... By studying the post-AGB stars we may be able to determine what causes the complicated structures seen in some planetary nebulae. To investigate this question, we have selected a well-defined sample of 86 post-AGB stars from a previous study of OH 1612-MHz maser sources in the Galactic plane (Sevenster et al., ...

... Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2012 February 5 . Lunation . ... Explanation: Our Moon's appearance changes nightly. This time-lapse sequence shows what our Moon looks like during a lunation , a complete lunar cycle. ... During the cycle, sunlight reflects from the Moon at different angles, and so illuminates different features differently. ... About APOD | ...

... 430 plots . ... 430 dome . 430 rcvr dome and carriage house centered at 430 MHz. interim correlator: . ... the old optical lab (or photometer lab) is on 110V Power from Building 1. several incandescent lights . ... seq: off, off . ... seq: on . ... A dotted purple line was made where it looked like rfi was coming from this location. spectral results 430 dome, all locations vertical scale .04Tsys (.ps) ( .pdf ) . spectral results 430 dome, all locations vertical scale .2 Tsys (.ps) ( .pdf ) . ...

Class 1 Introduction, Background History of Modern Astronomy The Night Sky, Eclipses and the Seasons Kepler's Laws Newtonian Gravity General Relativity Matter and Light Telescopes Class 2 Solar System Characteristics Formation Exosolar Planets Class 3 Stars The S un Stellar Evolution of Low and High Mass Stars Deaths of Stars Exotic Stars Class 4 Galaxies Galaxy Classification Formation of Galaxies Galactic ... Low mass stars live and die differently than high mass stars. ...

... Gauging the impact of executing science program across different COS/FUV lifetime positions . ... Changing Programs & Resolving Problems . ... The first such move occurred on 23 July 2012, when the COS FUV spectrum was moved to the COS FUV Lifetime Position 2 (LP2). ... It now appears that the move to COS/FUV Lifetime Position 3 will not occur until early 2015, and so a substantial fraction of Cycle 22 observationsare likely to occur at the COS FUV lifetime position 2, prior to the change. ...

... 18.04.2004 . ... Credit Copyright: KPNO 0.9-m Telescope , AURA , NOAO , NSF Explanation: Astronomers divide stars into different spectral types . ... The seven main spectral types OBAFGKM are shown above with the spectrum of a single "O" star at the top followed by two spectra each from the progressively cooler designations, respectively. ... Our Sun has spectral type "G". ... April . ... April 2004 . ... Publications with keywords: stars - spectrum . Publications with words: stars - spectrum . ...

Note that different students may see different quiz forms.) ... Giant stars are rare because . a) they do not form as often as main sequence stars. b) giant stars are unstable. c) the giant stage is very short compared to the main sequence stage. d) elements heavier than helium are relatively rare. In a color-magnitude diagram of a star cluster, the blue end of the main sequence is useful for defining the age of the cluster because . ... 2) Some idea. 3) Good idea. ...

... Science Activities > PhD Thesis Topics offered by ESO Faculty Members > Thesis Topic: Constraining Stellar Interiors and Mixing via Depletion Sequences of Light Elements . ... Observing with ESO Telescopes . ... ESO-MIDAS . ... ESO Data . ... ESO HST Image Galleries . ... ESO Data Access Policy . ... ESO Science Newsletter . ... Lithium (Li), beryllium (Be) and boron (B), usually referred to as "the light elements", represent a powerful diagnostic for studying stellar interiors and stellar mixing. ...

home education > activities . ... Quick math activity that asks students to calculate scale models of a binary star system with a black hole in it. [h] . ... Students use a radiometer and a light bulb with a dimmer switch to make connections between the temperature, color, and radiation output of a star. ... This demonstration, similar to the above, from the Exploratorium Snack-book of science activities, lets students demonstrate how molecules scatter light and change the colors of the beam. [m,h] . ...

The following files list line and continuum emissivities from the Arcetri Spectral Code. ... File format (html): File format for the continuum files . ... File format (html): File format for binned line emission files Line emission - The emissivity is given for individual transitions greater than 10 -31 erg cm 3 s -1 Choose the electron density: Ne = 10^2 Ne = 10^3 Ne = 10^4 Ne = 10^5 Ne = 10^6 Ne = 10^7 Ne = 10^8 Ne = 10^9 Ne = 10^10 Ne = 10^11 Ne = 10^12 Ne = 10^13 Ne = 10^14 . ...

Atmospheric influence on the different radio-engineering system functioning . ESTIMATION OF ATMOSPHERIC OPTICAL CHARACTERISTICS AND REMOTELY SANSED IMAGE CORRECTION . ... Direct transmittance estimation results for 12 channels of the spectrometer CHRIS. ... We have managed to develop a direct method of estimating the discrete Normalized Atmospheric Point Spread Function (NAPSF) from available images alone, not using any external sources of information about the atmosphere. ... IRE RAS 1996-20 11 ...

Plasma is sometimes called "the fourth state of matter", beyond the familiar three--solid, liquid and gas. It is a gas in which atoms have been broken up into free-floating negative electrons and positive ions , atoms which have lost electrons and are left with a positive electric charge. ... The fluorescent lamp , widely used in the home and at work, contains plasma (main constituent, mercury vapor) which is heated and agitated by electricity, from the power line to which the lamp is connected. ...

... The evolution of magnetic fields in OB-type stars from the study of open clusters of different ages . ... Wade G. A. The MiMeS Project: Magnetism in Massive Stars . ... Polosukhina N., Shavrina T., Drake N., Kudryavtsev D. Smirnova M. New results of the spectral observations of CPstars in the Li I 6708? spectral region with BTA telescope of SAO RAS . ... Magnetic Stars-2010 . ... List of participants . List of reports . ... Laboratory for the Stellar Magnetism Study of SAO of the RAS . ...

. Astronomers have used observations from HubbleтАЩs CANDELS survey to explore the sizes, shapes, and colors of distant galaxies over the last 80 percent of the universeтАЩs history. In the universe today, galaxies come in a variety of different forms and are classified via a system known as the Hubble Sequence тАФ and it turns out that this sequence was already in place as early as 11 billion years ago. // NASA/ESA

Next: Post main sequence stars Up: Principal Evolutionary States of Previous: Principal Evolutionary States of . ... The duration of the first stage is set equal to the hydrogen burning time, , which is a known function of the stellar mass only (Iben and Tutukov, 1987[ 75 ]): . The radius of the ZAMS star   is . ... A MS-star that accretes matter during the first mass transfer is considered to be a rapidly rotating Be-star that is distinguished by its different stellar wind rate (see below). ...

... 1) The MS lower envelopes for groups of stars with different metallicities turn out to be coincident. ... 4) The conformation of the kinematics of stars within narrow ranges ob b-y with the ages derived from isohrones reveals that, at Z < Z , the isohrone ages seem to be increasingly overestimated with growing b-y . ... At a given metallicity, they have a much narrower MS and the locus of their MS lower envelope seems to be brighter for the metal-rich group of stars. ...

... Different sections of an image may have different exposure. ... The obvious remedy for this is to divide the input image by the exposure map before smoothing. ... If you wish to create a background map in counts per pixel from an XMM exposure in which the exposure time varies significantly between CCDs, then you will need to remultiply the the output image by the exposure map; if however you wish to create a mosaic from several different cameras or pointings, you may wish not to do so. ...

... Amorphous carbonaceous materials can show a great diversity of optical properties due to the variability in their microstructure. ... The differently pyrolized celluloses are representative for a suit of carbonaceous material ranging from strongly disordered (insulating) to graphitized (conducting) material. Figure: Complex refractive index of hydrogenated amorphous carbon prepared by pyrolysis (annealing) of cellulose at different temperatures. ...