Astrophysics collection (March 11, 2016)

Latest astrophysics news

Rotation curves of galaxies as a test of MOND?

Galaxies are rotating with such speed that the gravity generated by their observable matter could not possibly hold them together. In a recent paper (Haghi et al. 2016) the authors test the Modified Newtonian Dynamics (MOND). Read>>

A binary origin for a central compact object (CCO)?

Doroshenko et al. 2016 investigate the possible binary origin of the CCO XMMUJ173203.3-344518. Read>>

Rapidly rotating pulsars as possible sources of fast radio bursts (FRB)

In a recent paper (Lyutikov et al. 2016) the authors discuss possible association of fast radio bursts (FRBs) with supergiant pulses emitted by young pulsars. Read>>

Supernovae from WD-WD direct collisions

In recent years it was suggested that WD-WD direct collisions (probably extremely rare and occurring only in dense stellar clusters) provide an additional channel for supernova explosions. Read>>

Telescopes Combine to Push Frontier on Galaxy Clusters

Hubblesite news. Read>>

No correlation between Fermi GBM signal and GW150914.

The electromagnetic signal detected by Fermi GBM is likely unrelated to the BH merger detected by LIGO. Read>>

Comments

A SIGNIFICATIVE FRACTION OF BARYONS RESIDE IN THE FILAMENTS OF THE COSMIC WEB

(Credit: NASA, ESA, and E. Hallman (University of Colorado, Boulder) Observations of the cosmic microwave background indicate that baryons (protons, neutrons, etc., - the ordinary matter just to understand) occupies only 5% of the total energy content of the Universe (95% is dark matter and dark energy). However in the local universe approximately half of this "ordinary" matter it has never been observed.

A UNIVERSE WITHOUT A CENTER?

Image Credit: Eugenio Bianchi, Carlo Rovelli & Rocky Kolb. According to the standard theories of cosmology, there is no center of the universe. In a conventional explosion, material expand out from a central point and the instinct suggests that with the Big Bang happened something similar. But the Big Bang was not an explosion like that at all: it was an explosion of space, not an explosion in space . The Big Bang happened everywhere in the Universe.

A Sapphire Super-Earth

Twenty-one light years away, in the constellation Cassiopeia, a planet by the name of HD219134 b orbits its star with a year that is just three days long. With a mass almost five times that of Earth, it is what is known as a super-Earth. Unlike our planet, however, these super-Earths were formed at high temperatures close to their host star and contain high quantities of calcium, aluminum and their oxides – including sapphire and ruby. HD219134 b is one of three candidates likely to belong to a new, exotic class of exoplanets. These objects are completely different from the majority of Earth-like planets. They have 10 to 20 percent lower densities than Earth. Researchers looked at different scenarios to explain the observed densities. For example, a thick atmosphere could lead to a lower overall density. But two of the exoplanets studied, 55 Cancri e and WASP-47 e, orbit their star so closely that their surface temperature is almost 3,000 degrees and they would have lost this ...

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