... 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 . ...