In this gallery are many images of Low Surface Brightness Galaxies which have recently been discovered and analyzed. ... The central surface brightness of this galaxy is 24.28 . Malin 2 This galaxy is another huge disk galaxy with a scale length of 15 kpc and a redshift of 15000 km/a. The high surface brightness knot in one of its spiral arms actually has the same color, luminosity and H-alpha equivalent width as the entire Large Magellanic Cloud . ... Truly it is a Low Surface Brightness Galaxy. ...

The "ring of fire" seen by satellite cameras around the polar caps (picture below) is probably created by electrons leaking from the tail's plasma sheet, whose magnetic field lines form a somewhat imperfect trap. ... One possible explanation involves the close association between auroral arcs and electric currents which flow along field lines between the ionosphere and distant space ( Birkeland currents ). ... That produces an extra resistance to the flow of current. ...

... NASA Explanation: Only a few short years ago , when the APOD editors were in graduate school, the pervasive, cosmic Dark Energy was not even seriously discussed. ... In fact, recent brightness measurements of distant and therefore ancient , stellar explosions or supernovae indicate that the universal expansion began to speed up in earnest four to six billion years ago, when the Dark Energy's repulse force began to overcome the attractive force of gravity over cosmic distances. ...

. Please standby and you will be automatically connected to the new location of the unframed Supernova page. Or, click on the link above. If you have questions or problems, please email me at David Bishop dbishop@vhdl.org . Last modified: Mon Aug 27 12:40:15 EDT 2001

Properties of the Dark Energy P. M. Garnavich University of Notre Dame A non-zero cosmological constant is only one of many possible ex- planations for the observed accelerating expansion of the Universe. Any smooth, dark energy with a signi cant negative pressure can drive the acceleration and this generic solution has been dubbed \quintessence". ... Quintessence can be parameterized by its equation of state, w = p=, which in the most general form can vary over time. ...

My Path to the Accelerating Universe Adam G. Riess Introduction Supernovae and the Expansion History of the Universe. From antiquity to the time of Albert Einstein, scientists and philosophers believed that the Universe was static and immutable. ... For example, a doubling of the Universe's size between the time the photon leaves the supernova and reaches the Hubble Space Telescope results in a doubling of the wavelength of light. ... 1998, Perlmutter et al. 1998). ...

... The Galactic low-mass X-ray binary GS 2023+338 was discovered during the burst on May 22, 1989 with the Japanise satellite Ginga (aka Galaxy). The flux reached 17 crabs (this unit of flux measurement is an bright X-ray source, Crab Nebula) at 10-35 keV. ... No other radio telescope worldwide carried out multi-frequency measurements. ... Upon 14 days the radio flux fell below the detection level at the RATAN-600 in relation to the decrease of the X-ray flux. ...

... Bad Astronomy . ... Mad Science . ... Universe Today . ... Keep Bad Astronomy close to your heart, and help make me filthy rich. ... As we look farther out, to more distant objects, we see that they are rushing away from us. ... If the Universe is open, it will expand forever. ... If the Universe is flat, it is forever balanced between open and closed; it will expand forever, but always slowing, just balancing gravity. ... 2008 Phil Plait. ... Subscribe to the Bad Astronomy Newsletter! ...

The ESA/ESO Astronomy Exercise Series 2 . The Distance to Messier 100 as Determined by Cepheid Variable Stars . ... The small variations in distance to the individual Cepheid variable stars in the Cloud are negligible compared with the much larger distance to the SMC. ... In this way Cepheid variable stars can be used as one of the 'standard candles' in the Universe that act either as distance indicators themselves or can be used to calibrate (or set the zero point for) other distance indicators. ...

... Based on this data the old idea of a cosmological constant is making a comeback. ... The gravitational effect of matter caused an acceleration in this model which Einstein did not want, since at the time the Universe was not known to be expanding. ... This term acts like a vacuum energy density , an idea which has become quite fashionable in high energy particle physics models since a vacuum energy density of a specific kind is used in the Higgs mechanism for spontaneous symmetry breaking. ...

... It turns out one possibility is a form of matter/energy invented by Einstein in the 1920s to make sure his equations of General Relativity did not predict the Expansion of the Universe. Although Einstein was willing to predict several things with his equations of General Relativity, he obviously thought an expanding Universe was too much, and so he invented the Cosmological Constant, which repels itself, and was meant to balance the force of gravity, and make the Universe static. ...

... ATNF Home . About ATNF . ... About ATNF overview . ... Governance overview . Australia Telescope Steering Committee . ... Australia Telescope User Committee . ... Our people overview . ... Publications overview . ... Careers overview . ... ATNF facilities . ... Parkes radio telescope . Australia Telescope Compact Array . ... Parkes | ... Visiting Parkes radio telescope . ... Parkes radio telescope webcam . ... Surface brightness measurements of . extended galactic nebulae . ...

... Using a simple 2-D Gaussian Point Spread Function (PSF) on a constant (flat) sky background, I derive a theoretical photometric and astrometric performance model for analytical and digital PSF-fitting stellar photometry. ... The photometric performance is maximized when either the effective background area or the effective-background-level measurement error is minimized. ... An important, but frequently ignored, noise source is the uncertainty of the measurement of the effective background level ( )...

... Positive Start of the data set. fragments present at the centre of the region and negative ones scattered around. Two major negative fragments locate at both east and west sides of the positive ones. At the west, positive fragments touch the negative ones. ... 01:45 The BP becomes A few negative fragments emerge near the stronger and positive ones at the east and move toward bigger. them. At the west, positive fragments keep moving toward the negative ones and cancellation continues. ...

I-GALFA Reveals Dynamic Events in Our Galaxy . S. J. Gibson, J.-h. Kang, B.-C. Koo, June 2009 . ... The white stripe marks the Galactic equator ( b=0 ). ... I-GALFA three-color H I image for FVW40.0+0.5, integrated over v lsr = -100 to -90 km/s ( red ), -90 to -80 km/s ( green ), and -80 to -70 km/s ( blue ). ... I-GALFA data reveal a complex tracery of loops, filaments, and blobs hundreds of parsecs above and below the Galactic plane, with isolated compact clouds extending even higher. ...

... Tonight's Sky . ... Observing . ... Sky this Month . ... Is cosmic acceleration changing? A new analysis shows that dark energy, the engine driving the universe's speeding expansion, may be changing fast. ... Cosmic acceleration is the biggest mystery in all of science," says University of Chicago cosmologist Michael Turner. ... for measuring dark-energy changes. ... and any change in dark energy's acceleration ? ... Only registered members of Astronomy.com are allowed to comment on this article. ...

Microsymposium 38, MS083, 2003 (A4 format) MERCURY: LOCAL VARIATIONS OF THE PHOTOMETRIC RELIEF. ... Because of trajectory and pointing angle constraints the planet could be observed from Mariner 10 only over a small range of phase angles between about 75o and 110o. Therefore the photometric investigations are restricted to measuring the distribution of brightness on the Mercurian disk. ... Raw versions of real-time processing pictures FDS 0000984 and FDS 0000986 were used (images 196 and 202). ...

... A cosmological surprise: the universe accelerates . ... The average energy density determines the fate of a homogeneous and isotropic universe governed by gravitational forces. ... The other parameter describes the change of the expansion and depends on the energy density and the curvature of the universe. ... Observing supernovae . ... The result from the distant supernovae that the expansion of the universe is not decelerating but in fact accelerates is certainly surprising. ...

The CHIANTI database consists of 4 primary ASCII files for each ion in the database. contains the energy levels in cm^(-1) It includes both experimental data and theoretical values of the levels energies. References: %observed energy levels (n=2): Fuhr, J.R., et al., NIST Atomic Spectra Database" ver. ... NIST Physical Reference Data %observed energy levels (12,19,23-26,65-67,69,70,72-74,78-82,84,85): Fuhr, J.R., et al., ...

... Aurora from Space . ... Magnetic Storms . ... The "ring of fire" seen by satellite cameras around the polar caps (picture below) is probably created by electrons leaking from the tail's plasma sheet, whose magnetic field lines form a somewhat imperfect trap. ... One possible explanation involves the close association between auroral arcs and electric currents which flow along field lines between the ionosphere and distant space ( Birkeland currents ). ... Why no aurora at the magnetic poles? ...