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October 21 2016

Tags: untagged
Reposted byowlssmirekstraycatznuhYggrykartoNikMeeresbraut

October 20 2016

Mysterious Cosmic Objects Erupting in X-rays Discovered
(NASA: Chandra, 19 Oct 2016)
Tags: science
Reposted byastronomygroupDevaelisah

(ESA, 20 October 2016)  Essential data from the ExoMars Schiaparelli lander sent to its mothership Trace Gas Orbiter during the module’s descent to the Red Planet’s surface yesterday has been downlinked to Earth and is currently being analysed by experts.

Early indications from both the radio signals captured by the Giant Metrewave Radio Telescope (GMRT), an experimental telescope array located near Pune, India, and from orbit by ESA’s Mars Express, suggested the module had successfully completed most steps of its 6-minute descent through the martian atmosphere. This included the deceleration through the atmosphere, and the parachute and heat shield deployment, for example.

But the signals recorded by both Pune and Mars Express stopped shortly before the module was expected to touchdown on the surface. Discrepancies between the two data sets are being analysed by experts at ESA’s space operations centre in Darmstadt, Germany.

The detailed telemetry recorded by the Trace Gas Orbiter was needed to better understand the situation. At the same time as Schiaparelli’s descent, the orbiter was performing a crucial ‘Mars Orbit Insertion’ manoeuvre – which it completed successfully. These important data were recorded from Schiaparelli and beamed back to Earth in the early hours of Thursday morning.

The data have been partially analysed and confirm that the entry and descent stages occurred as expected, with events diverging from what was expected after the ejection of the back heat shield and parachute. This ejection itself appears to have occurred earlier than expected, but analysis is not yet complete.

The thrusters were confirmed to have been briefly activated although it seems likely that they switched off sooner than expected, at an altitude that is still to be determined.
Tags: science

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.
Tags: science
Reposted byastronomygroupbesenpaket

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.
Tags: science
Reposted byastronomygroupe-gruppep-093-read

September 21 2016

Virtually unwrapped En-Gedi scroll

(W.B. Seales, C.S. Parker et al.  "From damage to discovery via virtual unwrapping: Reading the scroll from En-Gedi", Science Advances, DOI: 10.1126/sciadv.1601247, 21 Sep 2016)
Reposted byBlue-sing Blue-sing

September 12 2016


September 09 2016

Tags: science
Reposted byastronomygroup astronomygroup

September 05 2016

Philae found! (ESA, 5 Sept 2016)
Tags: science
Reposted byastronomygroupjalokim0Kladderadatschriotyouambesensofiaspaketbugienordernzerocool911namelessczinok

August 26 2016

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A High Stellar Velocity Dispersion and ~100 Globular Clusters for the Ultra Diffuse Galaxy Dragonfly 44
by Pieter van Dokkum, Roberto Abraham, et al.
http://arxiv.org/abs/1606.06291v1 (20 Jun 2016)

Recently a population of large, very low surface brightness, spheroidal galaxies was identified in the Coma cluster. The apparent survival of these Ultra Diffuse Galaxies (UDGs) in a rich cluster suggests that they have very high masses. Here we present the stellar kinematics of Dragonfly 44, one of the largest Coma UDGs, using a 33.5 hr integration with DEIMOS on the Keck II telescope. We find a velocity dispersion of 47 km/s, which implies a dynamical mass of M_dyn=0.7x10^10 M_sun within its deprojected half-light radius of r_1/2=4.6 kpc. The mass-to-light ratio is M/L=48 M_sun/L_sun, and the dark matter fraction is 98 percent within the half-light radius. The high mass of Dragonfly 44 is accompanied by a large globular cluster population. From deep Gemini imaging taken in 0.4" seeing we infer that Dragonfly 44 has 94 globular clusters, similar to the counts for other galaxies in this mass range. Our results add to other recent evidence that many UDGs are "failed" galaxies, with the sizes, dark matter content, and globular cluster systems of much more luminous objects. We estimate the total dark halo mass of Dragonfly 44 by comparing the amount of dark matter within r=4.6 kpc to enclosed mass profiles of NFW halos. The enclosed mass suggests a total mass of ~10^12 M_sun, similar to the mass of the Milky Way. The existence of nearly-dark objects with this mass was unexpected, as galaxy formation was thought to be maximally-efficient in this regime.

(Scientists Discover Massive Galaxy Made of 99.99 Percent Dark Matter)
Tags: science
Reposted bybesenbollabolla

August 25 2016

Joe Biden: "Peace For Our Time"
"The settlement of the Syrian problem, which has now been achieved is, in my view, only the prelude to a larger settlement in which all Near East may find peace. This morning I had another talk with the Turkish President, Herr Erdoğan, ... I believe it is peace for our time. We thank you from the bottom of our hearts. Go home and get a nice quiet sleep."

"America has been offered a choice between war and shame. She has chosen shame, and will get war." (Winston Churchill)
Tags: politics

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. [...]"
Tags: science
Reposted byastronomygroupp856

August 11 2016

Leaving the EU...

Long-term persistence

by Luigi Guiso, Paola Sapienza, Luigi Zingales
Journal of the European Economic Association. doi:10.1111/jeea.12177 (Jul 2016)

We study whether a positive historical shock can generate long-term persistence in development. We show that Italian cities that achieved self-government in the Middle Ages have a higher level of civic capital today than similar cities in the same area that did not. The size of this effect increases with the length of the period of independence and its intensity. This effect persists even after accounting for the fact that cities did not become independent randomly. We conjecture that the Middle-Age experience of self-government fostered self-efficacy beliefs—beliefs in one's own ability to complete tasks and reach goals—and this positive attitude, transmitted across generations, enhances civic capital today. Consistently, we find that fifth-graders in former free city-states exhibit stronger self-efficacy beliefs and that these beliefs are correlated with a higher level of civic capital.
Tags: politics

August 10 2016

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Explaining disappearing stars... (KH 15D)
Tags: science

August 09 2016

"No object was presented during the final video. The silent videos precluded the use of false verbal suggestions, and participants were not asked leading questions about the objects. Nevertheless, 32% of participants reported having visual impressions of non-existent objects."

The Phantom Vanish Magic Trick: Investigating the Disappearance of a Non-existent Object in a Dynamic Scene
by Matthew L. Tompkins, Andy T. Woods, Anne M. Aimola Davies
Frontiers in Psychology, dx.doi.org/10.3389/fpsyg.2016.00950 (21 Jul 2016)
Tags: science

August 05 2016

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... approaching steadily (with minor course corrections Jan & Jul 2012) ...

KIC 8462852 Faded Throughout the Kepler Mission
by Benjamin T. Montet, Joshua D. Simon
http://arxiv.org/abs/1608.01316 (3 Aug 2016)

KIC 8462852 is a superficially ordinary main sequence F star for which Kepler detected an unusual series of brief dimming events. We obtain accurate relative photometry of KIC 8462852 from the Kepler full frame images, finding that the brightness of KIC 8462852 monotonically decreased over the four years it was observed by Kepler. Over the first ~1000 days, KIC 8462852 faded approximately linearly at a rate of 0.341 +/- 0.041 percent per year, for a total decline of 0.9%. KIC 8462852 then dimmed much more rapidly in the next ~200 days, with its flux dropping by more than 2%. For the final ~200 days of Kepler photometry the magnitude remained approximately constant, although the data are also consistent with the decline rate measured for the first 2.7 yr. Of a sample of 193 nearby comparison stars and 355 stars with similar stellar parameters, 0.6% change brightness at a rate as fast as 0.341 +/- 0.041 percent per year, and none exhibit either the rapid decline by >2% or the cumulative fading by 3% of KIC 8462852. We examine whether the rapid decline could be caused by a cloud of transiting circumstellar material, finding while such a cloud could evade detection in sub-mm observations, the transit ingress and duration cannot be explained by a simple cloud model. Moreover, this model cannot account for the observed longer-term dimming. No known or proposed stellar phenomena can fully explain all aspects of the observed light curve.
Tags: science

July 24 2016

"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 byastronomygroup astronomygroup

July 16 2016

"Sehr bezeichnend für seine Anlagen waren nun die Spiele des kleinen Albert. Meist waren es Geduldspiele, Laubsägearbeiten, Erstellung komplizierter Bauten mit dem bekannten Ankersteinbaukasten, am liebsten aber der Bau vielstöckiger Kartenhäuser, womit er seine Musse ausfüllte." Maja Winteler-Einstein, sister of Albert Einstein.

Anker-Steinbaukasten children's building blocks by F. Ad. Richter & Cie., Rudolstadt, [Germany], c.1880s
Provenance: The set has passed by direct descent from Albert Einstein to the present owner.

Christie's, London, Valuable Books And Manuscripts,
Price Realized: $83,000 (13 July 2016)
Tags: untagged
Reposted bysofias sofias

July 15 2016

"Soldiers: free / Turks: 1.75 Lira / Syrians: 3.00 Lira"
Tags: politics

July 13 2016


Tracking the will to attend: Cortical activity indexes self-generated, voluntary shifts of attention
by Leon Gmeindl, Yu-Chin Chiu, et al.
Attention, Perception, & Psychophysics, DOI: 10.3758/s13414-016-1159-7 (June 2016)

The neural substrates of volition have long tantalized philosophers and scientists. Over the past few decades, researchers have employed increasingly sophisticated technology to investigate this issue, but many studies have been limited considerably by their reliance on intrusive experimental procedures (e.g., abrupt instructional cues), measures of brain activity contaminated by overt behavior, or introspective self-report techniques of questionable validity. Here, we used multivoxel pattern time-course analysis of functional magnetic resonance imaging data to index voluntary, covert perceptual acts—shifts of visuospatial attention—in the absence of instructional cues, overt behavioral indices, and self-report. We found that these self-generated, voluntary attention shifts were time-locked to activity in the medial superior parietal lobule, supporting the hypothesis that this brain region is engaged in voluntary attentional reconfiguration. Self-generated attention shifts were also time-locked to activity in the basal ganglia, a novel finding that motivates further research into the role of the basal ganglia in acts of volition. Remarkably, prior to self-generated shifts of attention, we observed early and selective increases in the activation of medial frontal (dorsal anterior cingulate) and lateral prefrontal (right middle frontal gyrus) cortex—activity that likely reflects processing related to the intention or preparation to reorient attention. These findings, which extend recent evidence on freely chosen motor movements, suggest that dorsal anterior cingulate and lateral prefrontal cortices play key roles in both overt and covert acts of volition, and may constitute core components of a brain network underlying the will to attend.
Tags: science
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