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October 20 2016

Mysterious Cosmic Objects Erupting in X-rays Discovered
(NASA: Chandra, 19 Oct 2016)
Reposted fromArchimedes Archimedes

October 16 2016

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Discovery of peculiar periodic spectral modulations in a small fraction of solar type stars
by Ermanno F. Borra & Eric Trottier
https://arxiv.org/abs/1610.03031 (10 Oct 2016)

A Fourier transform analysis of 2.5 million spectra in the Sloan Digital Sky Survey was carried out to detect periodic spectral modulations. Signals having the same period were found in only 234 stars overwhelmingly in the F2 to K1 spectral range. The signals cannot be caused by instrumental or data analysis effects because they are present in only a very small fraction of stars within a narrow spectral range and because signal to noise ratio considerations predict that the signal should mostly be detected in the brightest objects, while this is not the case. We consider several possibilities, such as rotational transitions in molecules, rapid pulsations, Fourier transform of spectral lines and signals generated by Extraterrestrial Intelligence (ETI). They cannot be generated by molecules or rapid pulsations. It is highly unlikely that they come from the Fourier transform of spectral lines because too many strong lines located at nearly periodic frequencies are needed. Finally we consider the possibility, predicted in a previous published paper, that the signals are caused by light pulses generated by Extraterrestrial Intelligence to makes us aware of their existence. We find that the detected signals have exactly the shape of an ETI signal predicted in the previous publication and are therefore in agreement with this hypothesis. The fact that they are only found in a very small fraction of stars within a narrow spectral range centered near the spectral type of the sun is also in agreement with the ETI hypothesis. However, at this stage, this hypothesis needs to be confirmed with further work. Although unlikely, there is also a possibility that the signals are due to highly peculiar chemical compositions in a small fraction of galactic halo stars.
Reposted fromArchimedes Archimedes

October 13 2016

"The Evolution fo Galaxy Number Denisty at Z < 8 and its Implications"
, by Christopher J. Conselice, Aaron Wilkinson, et al. (preprint 9 Oct 2016)

The evolution of the number density of galaxies in the universe, and thus also the total number of galaxies, is a fundamental question with implications for a host of astrophysical problems including galaxy evolution and cosmology. However there has never been a detailed study of this important measurement, nor a clear path to answer it. To address this we use observed galaxy stellar mass functions up to z ∼ 8 to determine how the number densities of galaxies changes as a function of time and mass limit. We show that the increase in the total number density of galaxies, more massive than M∗ = 10^6 M⊙ , decreases as φT ∼ t ^−1, where t is the age of the universe. We further show that this evolution turns-over and rather increases with time at higher mass lower limits of M∗ > 10^7 M⊙ . By using the M∗ = 10^6 M⊙ lower limit we further show that the total number of galaxies in the universe up to z = 8 is 2.0 × 10^12 (two trillion), almost a factor of ten higher than would be seen in an all sky survey at Hubble Ultra-Deep Field depth. We discuss the implications for these results for galaxy evolution, as well as compare our results with the latest models of galaxy formation. These results also reveal that the cosmic background light in the optical and near-infrared likely arise from these unobserved faint galaxies. We also show how these results solve the question of why the sky at night is dark, otherwise known as Olbers’ paradox.
Reposted fromArchimedes Archimedes

October 03 2016

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Rosetta slow descend to the surface of Comet 67P/Churyumov-Gerasimenko.
Reposted fromscience science viasergelanmi sergelanmi

September 30 2016

Rosetta's last image of Comet 67P/Churyumov-Gerasimenko, taken shortly before impact, at an altitude of 51 m above the surface. The image was taken with the OSIRIS wide-angle camera on 30 September 2016. The image scale is about 5 mm/pixel and the image measures about 2.4 m across.
Reposted byscienceSpecies5618danoniskowujcioBatblogmeertropfenelisahpaketyouamdrzdokhabarakhLarryGreenSkymennedetentacleguy

September 26 2016

Reposted fromscience science

September 25 2016

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Infinity ² (vimeo)
from Uncage the Soul Productions

Something internal and personal draws us out to the night sky. Under a blanket of stars and the Milky Way arcing over head, we ask the simple question "What do you feel?"

This short film follows 20 high schoolers far from the city lights to an Astronomy Camp; then joins the Oregon Star Party where 600 astronomers camp out with telescopes of all sizes during the Perseids Meteor Shower. Timelapse has been the only way to showcase the night sky in video; but with the new low-light technology of the Canon MH20f-SH, we film in the quiet moments that have been impossible to capture until now.
Reposted fromeglerion eglerion

September 21 2016

NASA will host a teleconference at 2 p.m. EDT Monday, Sept. 26, 2016, to present new findings from images captured by the agency’s Hubble Space Telescope of Jupiter’s icy moon, Europa. (Spoiler alert: NOT aliens)
Reposted fromscience science

September 18 2016

Gaia space telescope plots a billion stars

The most precise map of the night sky ever assembled is taking shape. Astronomers working on the Gaia space telescope have released a first tranche of data recording the position and brightness of over a billion stars. And for some two million of these objects, their distance and sideways motion across the heavens has also been accurately plotted.

Gaia's mapping effort is already unprecedented in scale, but it still has several years to run. Remarkably, scientists say the store of information even now is too big for them to sift, and they are appealing for the public's help in making discoveries.

To give one simple example of the scope of Gaia: Of the 1.1 billion light sources in Wednesday's data release, something like 400 million of these objects have never been recorded in any previous catalogue.

"You're imaging the whole sky in basically [Hubble] space telescope quality and because you can now resolve all the stars that previously maybe looked as though they were merged as one star at low resolution - now we can see them," explained Anthony Brown from Leiden University, Netherlands.

continue on bbc.com
Reposted fromscience science viaraindancer raindancer

September 14 2016

September 09 2016

Reposted fromArchimedes Archimedes

September 05 2016

Philae found! (ESA, 5 Sept 2016)
Reposted fromArchimedes Archimedes

August 25 2016

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like a sir
Reposted fromoopsiak oopsiak

August 12 2016

"The signal"
by "Pale Red Dot - A search for Earth-like planets around Proxima Centaury"

"So while we are convinced there is a signal in the Doppler measurements of Proxima, previous data do not allow to confirm its presence and clarify its origin. The long term variability of Proxima spoiled our attempts to combine data from previous observations so we needed a dedicated campaign. Combination of UVES and HARPS data at different cadences suggest that the star is showing a smoothly varying Doppler signal. Since the UVES survey set an upper limit between 2-3 Earth masses and if the signal is not activity induced, it must correspond to a planet smaller than that (between 1-2 Earth masses). The signal might well be caused by stellar activity, which should be quasi-periodic as opposed to the strict periodicity of the orbital motion of a putative planet. [...]"
Reposted fromArchimedes Archimedes
Formation of diverse ring-satellite systems around Centaurs through tidal disruption ... http://arxiv.org/abs/1608.03509 
Reposted byp856 p856

July 24 2016

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Reposted fromscience science viasergelanmi sergelanmi
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Reposted fromscience science viasergelanmi sergelanmi
"What the world’s oldest calculator tells us about the ancient Greeks' view of the universe", by Mike Edmunds, The Conversation, 20 July 2016
Reposted fromArchimedes Archimedes

July 23 2016

July 22 2016

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Our Place in the Cosmos
Reposted fromalexandersmith8805 alexandersmith8805
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