Next: This Work Previous: Rotation Periods of ZAMS Stars . ... There are currently several groups involved in the studies of the rotation periods of PMS stars. ... Overall, there are about 100 rotation periods known for PMS stars. ... Furthermore, the stars with periods near 8 days also tend to have infrared excesses which can be interpreted as arising from disks. ... In the first interpretation, the gap occurs because locking mechanism holds stars at a eight day rotation period. ...

Next: C.S. Jeffery, Research Astronomer Up: Research Previous: J.E. Chambers, Research Astronomer Contents . ... We examine spectral time-series of two lower-chromospheric lines observed with SUMER/SOHO (N I and C II ). ... Two examples of explosive events observed with SUMER/SOHO in transition region spectral lines are reported here; one detected in C IV 1548?, in a region within the northern polar coronal hole, and the other in O VI 1032?, in an active region. ...

. The seminar is supported by the grant of Federal Programm "Integration" . annotation of talk . S.N.Fabrika (SAO) . Magnetic fields and rotational periods of white dwarfs . Modern observing data on magnetic fields and rotational periods of single white dwarfs are reviewed. The data obtained with 6-m telescope are also discussed. It is shown in spite of considerable scatter in observed values the magnetic fields and rotational periods of white dwarfs are related as it may follow from the theory.

... The concept of continuous solar wind developed in 1950's. First, Biermann (1951, 1957) observed comet tails as they passed close to the Sun , and explained the observed tail deflection by a continuous flux of protons from the Sun. Then Parker (1959) showed that the solar corona must expand, and called the outward streaming coronal gas 'solar wind'. ... The expanding solar wind drags also the solar magnetic field outward, forming what is called the interplanetary magnetic field (IMF) . ...

HST Call for Proposals and HST Primer for Cycle 24 . ... Hubble Space Telescope Primer for Cycle 24 > Chapter 5: Observing Considerations > 5.1 Bright-Object Constraints . ... 5.1.1 ACS, COS & STIS . ... Data may also be affected by bright objects at limits that are substantially fainter than the safety limits discussed in the following sections. ... Bright object count rate limits are mode dependent. ... For the STIS MAMAs, these limits are given in Section 7.7 of the STIS Instrument Handbook . ...

... Science Users Information > Science and Technical Meetings > Conferences 2010 > The Origin and Fate of the Sun: Evolution of Solar-mass Stars Observed with High Angular Resolution . ... Observing Facilities . ... Observing with ESO Telescopes . ... The goal of this workshop is to review recent results on solar-mass stars obtained with infrared and millimeter interferometers, and to discuss their importance for our understanding of stellar evolution from star formation to stellar end products. ...

... Home Observing Clear Sky Chart . ... Lecture Series 2014-2015 . ... AAA Fall Astronomy Class: Astronomy Basics тАУ October-November 2015 . ... Clear Sky Chart . This Month's Sky . ... This MonthтАЩs Sky тАУ April 2015 . ... Beyond New York City . ... Observing Resources for Amateur Astronomers - Part 1: Beginning Observers . ... A History of the First Forty Years of the Amateur Astronomers Association . ... 2016 Amateur Astronomers Association of New York Designed by Press Customizr Powered by . ...

The "drifting subpulse" phenomenon has long been regarded as among the most important clues to understanding the origin of pulsar radio (and other) emission. These beautiful and highly organized sequences captivated both observers and theorists, but only in the last few years has the phenomenon been shown to represent a "carousel" of emitting subbeams, circulating around the magnetic axis of the rotating star---and this clearly as yet in only a single pulsar. ...

... ATNF Home . About ATNF . ... About ATNF overview . ... Governance overview . Australia Telescope Steering Committee . ... Parkes radio telescope . ... Information & tools for observers . ... Online Resources . ... Visiting Parkes radio telescope . ... Parkes radio telescope webcam . ... Recently, the OGLE team have reported a clear quasar microlensing signal in Q2237+0305. ... From light-curve fitting, I unambiguously set the source size of Einstein Ring radius as a conservative limit. ...

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. ...

... Note: Click here a longer, much more comprehensive overview of the polar aurora . ... Magnetic Field . ... Aurora . ... 3b. Fritz Aurora . ... Electrons . ... Typical aurora (Dick Hutchinson ї) . In Alaska, Canada, Norway, Finland or northern Russia, on a clear night, a greenish glow is often seen in the sky, known as the "Northern Lights." ... Auroral light is produced at a height of about 100 km (60 miles) when fast electrons, arriving from space, slam into atoms and molecules of the atmosphere. ...

... Fitting the observed dependence includes calculations of the polarization cross-sections averaged over particles orientation and size distribution, their normalization and the comparison of obtained dependencies with Serkowski's curve representing observational data for a chosen star. ... Variations of the polarization factors with wavelength are shown in Fig. 16 for homogeneous spheroidal particles with PF orientation. ... The distinction between prolate and oblate spheroids is also clearly seen. ...

... 12.07.2000 . ... The Crab Nebula in Blue and White . ... Comet LINEAR Extends . ... Comet LINEAR's tail appears to be extending. Many sky watchers are closely following Comet C/1999 S4 LINEAR and wondering if it will develop an impressive tail or become visible to the naked eye later this month. ... Comet C/1999 S4 LINEAR is rapidly approaching both the Earth and the Sun from the outer Solar System, and should be at its brightest around 2000 July 25 in the early evening sky of northern observers. ...

... Under certain conditions, like those in the nucleus of a QSO, all atoms can be made to emit light at particular wavelengths. ... If that source is approaching the observer, the wave is squashed up onto itself making the wavelength shorter. ... This is redshift. ... You can see how the section of the QSO spectrum which we observe changes with redshift. ... We then see how far we had to slide the observed spectrum along the scale to make it match and that is the objects redshift. ... The 2QZ team . ...

... This year's eclipse is unique in duration. ... Although, at the present time, there are 6 solar observatories belonging to leading space agencies in orbit around the Earth, the eclipse of 22 July, 2009, will only be seen by two of them: the Russian CORONAS-PHOTON satellite equipped with TESIS telescopes and Japan's HINODE satellite fitted with an XRT space telescope. ... TESIS will be the first of the two devices (and the very first on Earth) to witness the solar eclipse. ...

... The chemically peculiar star HD965 belongs to a rare type of very slow rotators. As far back as in the 90s, G.Mathys (ESO, Chile) supposed its extremely slow rotation as observing split Zeeman components in the spectrum, from which he measured the magnetic field on its surface. Field variation proved to be very slow, and G.Mathys determined that the variability period should be longer than two years. ... Up to now, only two stars with periods longer than 20 years are known. ...

... click image to view discuss) . ... Submitted by Philip Levine on 04/19/2015 22:29:32 . ... more kids getting first view of the Sun . ... enjoying the views . ... Sun shroud helps the view . ... Copyright (c) Amateur Telescope Makers of Boston, Inc. ...

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... Astronomical image processing applies a large variety of numerical methods to extract scientific results from observed data. The standard computational techniques used in this process are discussed with special emphasis on the problems and advantages associated with them when applied to astronomical data. ... In Section the transformation of raw observed data into intensity calibrated values is discussed while general image processing techniques are reviewed in Section . ... Basic Concepts . ...