... Bad Astronomy . ... Bitesize Astronomy . ... Last week's Snack talked about how black holes can affect the environment around them in such a way as to be very bright . ... It's a common misconception that black holes always have matter swirling into them. ... As this matter gets closer and closer to the black hole it piles up and a large, fairly flat disk forms. This is called the accretion disk , because matter from this disk accretes (that is, falls in) on the black hole. ... 2008 Phil Plait. ...

... Since the fast mode window is necessarily small, the source PSF fills much of the window (clearly evident for bright sources). ... As such, the source and background extraction apertures may be truncated by the window. ... While often there will be only one object in the image, one should check for spurious detections which could affect the analysis of the target source and also for missed sources or prominent objects in the window, which may contaminate the target. ...

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... The Russian TESIS/ CORONAS-PHOTON Solar Observatory, which has been working in orbit since January 30th, 2009, has photographed one of the most important events in the build up to the upcoming solar cycle - the formation of our star's new southern belt of activity. The first magnetic fields of the new cycle in the southern hemisphere appeared on the Sun's surface on May 23-24th. ... The belt of activity is one of the primary concepts, characterizing the solar cycle. ...

... 2014 January 29 . Jelly Donut Shaped Rock Appears on Mars . Image Credit: Mars Exploration Rover Mission , Cornell , JPL , NASA . Explanation: What if a rock that looked like a jelly donut suddenly appeared on Mars? ... Even so, the rock's unusual light tones surrounding a red interior created interest in its composition -- as well as causing it to be nicknamed Jelly Donut . ... About APOD | ... NASA Official: Phillip Newman Specific rights apply . ... A service of: ASD at NASA / GSFC . ...

... not more than 2 participants in the younger group. not more than 1 participant in the senior group. prizewinners (I-st or II-nd prize) of the previous IAO not older than the age limit who did not used such a possibility before. exactly 2 team leaders (specialists in astronomy or astronomy education). ... For the countries, starting their activity in the International Astronomy Olympiad and for the students participating the first time in IAO the age limits for the groups for IAO-2005 are defined as:...

... People . Posts tagged ?positional citation effect? ... The full article is found from [arXiv/astro-ph:0712.1037] . According to J. P. Dietrich , the positional citation effect (PCE) is significant so that preprints appeared at the top of daily lists tend to be more cited than other preprints. ... ArXiv] The Importance of Being First: Position Dependent Citation Rates on arXiv:astro-ph? Tags: astro-ph , citation , positional citation effect . ... 5 Comments . ... Entries RSS . ...

... Sagittarius Star Cloud . ... The color of a star indicates its surface temperature, an important property used to assign each star a spectral type. Most stars in the above Sagittarius Star Cloud are orange or red and relatively faint, as our Sun would appear. The Wind on Mars . ... The Earth's orbit is not a perfect, sun-centered circle. ... Venus Once Molten Surface . ... M6: The Butterfly Cluster . ... To some, the outline of the open cluster of stars M6 resembles a butterfly. ...

... SAO researchers have discovered that supercritical accretion disks eject hot gas with a velocity of a few thousand kilometers per second. The supercritical regime of accretion onto black holes is very important for astrophysics. In the first half-billion years just after our Universe was born, supermassive black holes (quasars) began to appear and grow in centers of young galaxies. ... Gas falling onto a black hole (accretion) is not a frequent phenomenon in our Galaxy. ...

... David P. Stern Laboratory for Extraterrestrial Physics NASA . ... Alfv?n's Theory and Electric Fields . ... The debate between proponents of a static corona, Parker's solar wind theory, and an alternative "solar breeze" theory of Chamberlai n [1960, 1961; Dessler 1967] was only settled by observations from space. ... Rapidly spreading plasma clouds produced by solar flares, like those envisioned by Chapman and Ferraro, are sometimes superposed on the solar wind flow. ...

... Circumstellar disc of beta Pictoris: constraints on grain properties from polarization. To appear in the Astronomy & Astrophysics . abs , src , ps ] . ... Dust influx to Titan from Hyperion . ... abs ] . ... Characteristics of bulges and disks in interacting galaxies . ... Dust grains around Herbig Ae/Be stars: porous, cometary-like grains? ... To appear in the Astronomy & Astrophysics Supplement . ... Finally, Links may lead you to more options (e.g. via the LANL preprint system). ...

Previous] [Up] . Given that spectra produced by GHRS are tilted across the diode array and that there are drifts with time which, it is very important that the nominal SPYBAL not be frivolously omitted. While the possible negative effects of not performing SPYBALS can be minimal for some wavelength/grating combinations, these effects are not readily predictable since they appear to be correlated with the recent thermal history of the instrument. ... GHRS Instrument Science Report 072 . ...

... The search for distant objects which can be both galaxies and quasars is one of the most important problems of observational astrphysics, because it allows one to determine cosmological parameters connected with the time of appearence and evolution of stellar systems, large scale structure of the Universe. ... Radio galaxies are important objects to be studied because they are sources of infrared-optical-ultraviolet continuum, emission lines and continual radio emission. ...

The Many Streams of the Magellanic Stream . ... As a part of the ongoing GALFA survey we have obtained an H I image of a region located at the tip of the Magellanic Stream. ... Figure 1 shows the velocity field of the tip of the Stream. ... Comparison with numerical simulations by Connors et al. (2006) suggests that a 3-way splitting of the main Stream filament may have taken place due to gravitational interactions between the SMC, the LMC, and the Galaxy. ... 2006) . ...

... David P. Stern Laboratory for Extraterrestrial Physics NASA . ... Alfv?n's Theory and Electric Fields . ... The debate between proponents of a static corona, Parker's solar wind theory, and an alternative "solar breeze" theory of Chamberlai n [1960, 1961; Dessler 1967] was only settled by observations from space. ... Rapidly spreading plasma clouds produced by solar flares, like those envisioned by Chapman and Ferraro, are sometimes superposed on the solar wind flow. ...

To construct frequency distribution (histogram) of minor planets according to value of some element/ parameter/ function user should first select Elements item in menu bar and then Histogram in drop-down menu. ... User has possibility to save histogram or to print it using standard means. To save the file select File item in menu bar and then Save As... in drop-down menu. ... To print histogram select File item in menu bar and then take advantage of options Print Preview , Print Setup , Print . ...

The Earth. ... The middle raiding of the Earth is 6371,032 km, the pole 6356,777 km equatorial - 6378,160 km. The Earth surface area is 510,2 mln km^2, 70,8% of which is the World ocean. ... According to the modern cosmogonical views the Earth was formed 4,6 - 4,7 billions years ago from the protoplanet cloud captured by the Sun. ... The Earth is conditionally divided into 3 parts: a bark a cloak and a core (in the centre). The external layer - the bark is 35 km thick. ... Above the Earth. ...

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. ...

Astronotes Armagh Planetarium's Stellar Blog! ... This image combines orbital imagery with 3-D modelling to show flows that appear in spring and summer on a slope inside Mars' Newton crater. ... Warm season flows on a slope in Newton Crater, possible evidence of salty liquid water active on Mars today. Image credit: NASA) . ... Frozen water is common on and under the surface of Mars but these images are the best evidence to date for the presence of liquid water on the Martian surface today. ...