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. ...

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... Binary orbits in the acceleration/period plane . Circular Orbits . ... We first present the equations for the period and acceleration of a pulsar in an eccentric binary system as a function of its position in the orbit. ... In Freire, Kramer & Lyne (2001) (from where most of this text and following equations are taken), we describe in more detail how circular binary orbits can be determined from the observed periods and accelerations of the pulsar. ... where is the orbital period of the binary. ...

... An estimate the rotation period of cometary nuclei is important for understanding and describing the physical processes of the cometary activity. Unfortunately, the measurements of the rotation periods of the comet nucleus depend on the model assumptions and it is one of the main reasons for the scatter of the estimates given in various articles for a given comet. ... Right: the image of the comet 29P/Schwassmann-Wachmann 1 obtained at the 6-m telescope. ...

Astronomy Picture of the Day . ... 26.08.2003 . ... Tonight and over the next few days, when Mars is at its closest approach to Earth in nearly 60,000 years, you might get your best view ever of our planetary neighbor. Please, though, don't expect to see this much structure , or expect to see Mars rotate so much in so brief a period. ... In reality, one full Martian rotation -- a Martian day -- is only about 40 minutes longer than an Earth day. ... Publications with keywords: Mars . ...

... The QBO period is equal to a linear combination of the frequencies corresponding to the doubled periods: of the tidal year (0.97 year ), of the regression of nodes (18.6 years ), and of the motion of perigee ( 8.85 years ) of the Earth's monthly orbit : 1 2 1 1 1 0.97 18.61 8.85 1 2.3 yr (1) In other words, the quasi-biennial oscillation of the wind direction in the equatorial stratosphere is a combined oscillation ...

. See more RATAN-600 solar data for the period from 2005 up to the current time at prognoz .

Nonlinear tides in giant planets Adrian Barker DAMTP, University of Cambridge (formerly at CIERA, Northwestern) With: C. Baruteau, B Favier, P Fischer, Y Lithwick, G Ogilvie Introduction Motivation · Shortest period hot Jupiters (M ~ MJup, P < 10 d) have preferentially circular orbits => thought to be explained by tidal dissipation inside the planet (e.g. Rasio et al,1996) If so, what mechanisms are responsible? ... Linear theory contains uncertainties (e.g. Zahn, Ogilvie, Papaloizou, Ivanov, Wu). ...

Uranus: around the Sun, "lying in the side". Uranus . ... Mass . ... The period of rotation . ... The average distance from the Sun . ... Excentricity of the orbit . ... Uranus is the seventh from the Sun great planet of the Solar system. ... The theoretical model of Uranus structure is following its upper layer is a gasoliquid shell under which is an icy cloak (the water and ammonia ice) then comes the core of the solid soils. The cloak and the core mass is about 85-90% of all Uranus mass. ...

Weekly Bulletin on Solar and Geomagnetic Activity Highlights on 20 - 26.06.2011, Forecast on 27.06 - 03.07.2011, Carrington Rotations 2111, 2112 (05,83.06 - 03,01.07.2011) SOLAR SUNSPOT ACTIVITY OF THE LAST PERIOD TO 26 JUNE WAS AT THE MIDDLE LEVEL, THEN ON LOW. ... NEXT WEEK A LEVEL OF SUNSPOT ACTIVITY IS EXPECTED LOW AND BY THE END OF THE PERIOD THE MIDDLE LEVEL. THE MOST LIKELY THE CALCULATED WEEKLY AVERAGE VALUE OF SUNSPOT NUMBER IN THE INTERNATIONAL SYSTEM FOR THE NEXT PERIOD W=030+10/-10. ...

... Apache HTTP Server Version 2.2 . Apache > HTTP Server > Documentation > Version 2.2 > Programs . ... rotatelogs is a simple program for use in conjunction with Apache's piped logfile feature. It supports rotation based on a time interval or maximum size of the log. ... For example, if the rotation time is 3600, the log file will be rotated at the beginning of every hour; if the rotation time is 86400, the log file will be rotated every night at midnight. ... date and time (localized) . ...

... 8, ``Celestial Mechanics'', 2002 FCN -- period dependence on dynamic characteristics of a lunar core A. Gusev 1 , N. Petrova 1 , N. Kawano 2 , and RISE group 2 1 Kazan State University, Kazan, Russia 2 National Astronomical Observatory, Mizusawa, Iwate, Japan Two modes in a polar oscillation are obtained when a free rotation of the two--layer Moon was studied: 1 PCW = 2\Omega A Am p fffi ё 1 74yr 1 P FCN = \ Gamma \Omega A 2Am ` C c \ ...

... Precisely one month ago, on 11 July 2009, the last active area of the new solar cycle disappeared from the surface of the Sun. Over the 30 days following this, neither observers on Earth nor devices in space have been able to detect the emergence of any sunspots. ... Therefore, it seems that our star has once again returned to a state of deep solar "winter", following several sparks of activity in May-June 2009. ... To date, this period has lasted 30 days. ...

... Just one: a very stringent requirement on the relative positions of Earth and Mars at the time of launch. ... Suppose the spacecraft which has landed on Mars is a robot , which collects a sample and immediately takes off again for its return trip. ... Since Earth and Mars constantly change their relative position, it stands to reason that if we sufficiently delay the return trip, Earth will move from position (2) relative to Mars to position (3), at which time the return trip can begin. ...

... Apache HTTP Server Version 2.2 . Apache > HTTP Server > Documentation > Version 2.2 > Programs . ... rotatelogs is a simple program for use in conjunction with Apache's piped logfile feature. It supports rotation based on a time interval or maximum size of the log. ... For example, if the rotation time is 3600, the log file will be rotated at the beginning of every hour; if the rotation time is 86400, the log file will be rotated every night at midnight. ... date and time (localized) . ...

... The Sun of our solar system is a typical star of intermediate size and luminosity. ... The Sun has a very complex surface magnetic field created by convective flow of the electrically conducting solar material. ... The escaping hot coronal plasma is called the solar wind . ... See the table below for the observed features above the Sun's surface. ... Chromospheric features . Coronal features . ... dense clouds of material suspended above the surface of the Sun by magnetic field line loops . ...

Superflares on solar-type stars Hiroyuki Maehara (Kyoto University) Collaborators: Takuya Shibayama, Shota Notsu, Yuta Notsu, Takashi Nagao, Satoshi Kusaba, Satoshi Honda, Daisaku Nogami & Kazunari Shibata Energy-frequency distribution of solar flares Large flares are less frequent than smaller ones. ... Summary We found 365 superflares on 148 solar-type stars 14 superflares on 10 Sun-like stars The energy-frequency distribution of superflares on solar-type stars is similar to that of solar flares. ...

... Astronomy for Kids . ... Astronomy 101 . ... Eicher book signing at Northeast Astronomy Forum . Buy and sell astronomy gear April 9 . ... How can astronomers find a planet's rotational period when they cannot see its surface? ... Because they don t have solid surfaces, we can t infer their periods from following the reoccurring surface features. ... Get instant access to subscriber content on Astronomy.com! ... If you are already registered on Astronomy.com, please log in below. ...

... Mass_Ratio ); /* Orbital Decay */ # declare Ttd = clock / Decay_Time; # declare clock_merge = Decay_Time * sqrt ( 1. - pow (( Contact / Init_Sep ),1.5) ) ; # declare t_merge = clock - clock_merge ; /* Semimajor axes */ # declare Orbital_Radius_1 = Initial_OrbSep_1 * pow((1.-pow(Ttd,2)),2./3.); # declare Orbital_Radius_2 = Orbital_Radius_1 / Mass_Ratio; # declare Orbital_Sep = Orbital_Radius_1 + Orbital_Radius_2; /* Periods and phases */ # ...

... 2005 September 17 . The Shadow of Phobos . Credit: Malin Space Science Systems , MGS , JPL , NASA . ... The area imaged is about 250 kilometers across and is seen in panels from left to right as red filter, blue filter, and combined color composite views from the MGS wide-angle camera system. The three dark spots most easily seen in the red filter image are likely small fields of dark sand dunes on crater floors. ... About APOD | ... NASA Web Site Statements, Warnings, and Disclaimers . ...