KREUZADER (Posts tagged astronomy)

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Mission to an Interstellar Asteroid“ A sky map showing the probability that a future interstellar asteroid will approach the Solar System on a trajectory parallel to that direction. The darker colors indicate a higher probability. The axes denote...

Mission to an Interstellar Asteroid

A sky map showing the probability that a future interstellar asteroid will approach the Solar System on a trajectory parallel to that direction. The darker colors indicate a higher probability. The axes denote degrees from a heliocentric point of view and the ecliptic is plotted in black. The sky positions of the constellations Serpens and Lepus, which are close in proximity to the Solar apex and anti-apex respectively, are plotted for context. The black circle indicates the sky location that ‘Oumuamua entered our Solar System, consistent with the prediction that the majority of these objects will approach with velocities parallel to the galactic apex.

Source: centauri-dreams.org
'oumuamua oumuamua asteroid astronomy space
A surprising chill before the cosmic dawn“The first two phases of the Universe were the ‘dark age’, before stars formed (grey), and the cosmic dawn (yellow), when clouds of hydrogen in early structures collapsed to form stars. The temperature of...

A surprising chill before the cosmic dawn

The first two phases of the Universe were the ‘dark age’, before stars formed (grey), and the cosmic dawn (yellow), when clouds of hydrogen in early structures collapsed to form stars. The temperature of radiation (TR) left over from the Big Bang has declined slowly over time. The spin temperature (TS) of hydrogen that has not formed stars reflects the excitation state of the hydrogen atoms (solid blue line shows previous estimates of TS based on models). Bowman et al.2 use observations to estimate TS, and find that it dropped to lower values (red solid line) than predicted by models. Barkana7 proposes that this could be evidence for a previously unrecognized, non-gravitational interaction between normal and dark matter. 

Source: nature.com
astrophysics cosmology space exploration astronomy radio astronomy
Proxima Flare May Force Rethinking of Dust Belts“News of a major stellar flare from Proxima Centauri is interesting because flares like these are problematic for habitability. Moreover, this one may tell us something about the nature of the planetary...

Proxima Flare May Force Rethinking of Dust Belts

News of a major stellar flare from Proxima Centauri is interesting because flares like these are problematic for habitability. Moreover, this one may tell us something about the nature of the planetary system around this star, making us rethink previous evidence for dust belts there.

But back to the habitability question. Can red dwarf stars sustain life in a habitable zone much closer to the primary than in our own Solar System, when they are subject to such violent outbursts? What we learn in a new paper from Meredith MacGregor and Alycia Weinberger (Carnegie Institution for Science) is that the flare at its peak on March 24, 2017 was 10 times brighter than the largest flares our G-class Sun produces at similar wavelengths (1.3 mm).

proxima centauri astronomy
Direct Multipixel Imaging and Spectroscopy of an Exoplanet with a Solar Gravity Lens Mission“ The remarkable optical properties of the solar gravitational lens (SGL) include major brightness amplification (~1e11 at wavelength of 1 um) and extreme...

Direct Multipixel Imaging and Spectroscopy of an Exoplanet with a Solar  Gravity Lens Mission

The remarkable optical properties of the solar gravitational lens (SGL) include major brightness amplification (~1e11 at wavelength of 1 um) and extreme angular resolution (~1e-10 arcsec) in a narrow field of view. A mission to the SGL carrying a modest telescope and coronagraph opens up a possibility for direct megapixel imaging and high-resolution spectroscopy of a habitable Earth-like exoplanet at a distance of up to 100 light years. The entire image of such a planet is compressed by the SGL into a region with a diameter of ~1.3 km in the vicinity of the focal line. The telescope, acting as a single pixel detector while traversing this region, can build an image of the exoplanet with kilometer-scale resolution of its surface, enough to see its surface features and signs of habitability. We report here on the results of our initial study of a mission to the deep outer regions of our solar system, with the primary mission objective of conducting direct megapixel high-resolution imaging and spectroscopy of a potentially habitable exoplanet by exploiting the remarkable optical properties of the SGL. Our main goal was to investigate what it takes to operate spacecraft at such enormous distances with the needed precision. Specifically, we studied i) how a space mission to the focal region of the SGL may be used to obtain high-resolution direct imaging and spectroscopy of an exoplanet by detecting, tracking, and studying the Einstein ring around the Sun, and ii) how such information could be used to detect signs of life on another planet. Our results indicate that a mission to the SGL with an objective of direct imaging and spectroscopy of a distant exoplanet is challenging, but possible. We composed a list of recommendations on the mission architectures with risk and return tradeoffs and discuss an enabling technology development program.
Source: arxiv.org
astronomy space
lordtableshark
astronomyblog

IceCube ( IceCube Neutrino Observatory)

IceCube, the South Pole neutrino observatory, is a cubic-kilometer particle detector made of Antarctic ice and located near the Amundsen-Scott South Pole Station. It is buried beneath the surface, extending to a depth of about 2,500 meters. A surface array, IceTop, and a denser inner subdetector, DeepCore, significantly enhance the capabilities of the observatory, making it a multipurpose facility.

IceCube is the first gigaton neutrino detector ever built and was primarily designed to observe neutrinos from the most violent astrophysical sources in our universe. Neutrinos, almost massless particles with no electric charge, can travel from their sources to Earth with essentially no attenuation and no deflection by magnetic fields.

The in-ice component of IceCube consists of 5,160 digital optical modules (DOMs), each with a ten-inch photomultiplier tube and associated electronics. The DOMs are attached to vertical “strings,” frozen into 86 boreholes, and arrayed over a cubic kilometer from 1,450 meters to 2,450 meters depth. The strings are deployed on a hexagonal grid with 125 meters spacing and hold 60 DOMs each. The vertical separation of the DOMs is 17 meters.

Eight of these strings at the center of the array were deployed more compactly, with a horizontal separation of about 70 meters and a vertical DOM spacing of 7 meters. This denser configuration forms the DeepCore subdetector, which lowers the neutrino energy threshold to about 10 GeV, creating the opportunity to study neutrino oscillations.

IceTop consists of 81 stations located on top of the same number of IceCube strings. Each station has two tanks, each equipped with two downward facing DOMs. IceTop, built as a veto and calibration detector for IceCube, also detects air showers from primary cosmic rays in the 300 TeV to 1 EeV energy range. The surface array measures the cosmic-ray arrival directions in the Southern Hemisphere as well as the flux and composition of cosmic rays.

Developments in neutrino astronomy have been driven by the search for the sources of cosmic rays, leading at an early stage to the concept of a cubic-kilometer neutrino detector. Cosmic rays, which consist mainly of protons, are the highest energy particles ever observed, with energies over a million times those reached by today’s particle accelerators on Earth.

AMANDA, the Antarctic Muon and Neutrino Detector Array, was built as a proof of concept in the mid 1990s and demonstrated that the extremely clear Antarctic ice was suitable for detecting energetic neutrinos. IceCube, the only cubic-kilometer neutrino detector constructed to date, was completed in December 2010, only six years after the deployment of the first string at the South Pole.

Neutrinos are not observed directly, but when they happen to interact with the ice they produce electrically charged secondary particles that in turn emit Cherenkov light, as a result of traveling through the ice faster than light travels in ice.

The IceCube sensors collect this light, which is subsequently digitized and time stamped. This information is sent to computers in the IceCube Lab on the surface, which converts the messages from individual DOMs into light patterns that reveal the direction and energy of muons and neutrinos.

The IceCube Neutrino Observatory was built under a National Science Foundation (NSF) Major Research Equipment and Facilities Construction grant, with assistance from partner funding agencies around the world. The NSF Office of Polar Programs supports the project with a Maintenance and Operations (M&O) grant. The University of Wisconsin–Madison is the lead institution, coordinating data-taking and M&O activities. The international IceCube Collaboration, with more than 40 institutions worldwide, is responsible for the scientific research program.

Source: icecube.wisc.edu Images: iceCube/NSF,Mike Lucibella, Sven Lidstrom, Jim Haugen, B. Gudbjartsson.

physics astronomy neutrino
Charged oxygen in ionosphere may offer biomarker for exoplanets“Most planets in our solar system have some oxygen in their lower atmospheres, but Earth has much more, about 21 percent. This is because so many organisms have been busy turning light,...

Charged oxygen in ionosphere may offer biomarker for exoplanets

Most planets in our solar system have some oxygen in their lower atmospheres, but Earth has much more, about 21 percent. This is because so many organisms have been busy turning light, water, and carbon dioxide into sugar and oxygen—the process called photosynthesis—for the past 3.8 billion years.

[…]

On Earth today, excess oxygen molecules, in the form of O2, float upward. When the O2 gets about 150 kilometers above the Earth’s surface, ultraviolet light splits it in two. The single oxygen atoms float higher, into the ionosphere, where more ultraviolet light and x-rays from the sun rip electrons from their outer shells, leaving charged oxygen zipping through the air. The abundance of O2 near the Earth’s surface—so different than the other planets—leads to an abundance of O+ high in the sky.

This finding, says Mendillo, suggests that scientists seeking extraterrestrial life could perhaps narrow their search area.

Source: bu.edu
exobiology astronomy seti
Proxima’s orbit around Alpha Centauri“Proxima and Alpha Centauri AB have almost identical distances and proper motions with respect to the Sun. Although the probability of such similar parameters is in principle very low, the question as to whether...

Proxima’s orbit around Alpha Centauri

Proxima and Alpha Centauri AB have almost identical distances and proper motions with respect to the Sun. Although the probability of such similar parameters is in principle very low, the question as to whether they actually form a single gravitationally bound triple system has been open since the discovery of Proxima one century ago. Owing to HARPS high precision absolute radial velocity measurements and the recent revision of the parameters of the Alpha Cen pair, we show that Proxima and Alpha Cen are gravitationally bound with a high degree of confidence. The orbital period of Proxima is approximately 550 000 years. With an excentricity of 0.50 (+0.08 -0.09), Proxima comes within 4.3 (+1.1 -0.9) kau of Alpha Cen at periastron. Its orbital phase is currently close to apastron (13.0 +0.3 -0.1 kau). This orbital motion may have influenced the formation or evolution of the recently discovered planet orbiting Proxima as well as circumbinary planet formation around Alpha Cen.

Source: arxiv.org
alpha centauri proxima centauri astronomy space
Will Astronomers Be Ready for the Next ‘Oumuamua?“In a letter published February 6 in Monthly Notices of the Royal Astronomical Society, Marcos and his collaborators considered 339 known hyperbolic objects, using a computer model to rewind their...

Will Astronomers Be Ready for the Next ‘Oumuamua?

In a letter published February 6 in Monthly Notices of the Royal Astronomical Society, Marcos and his collaborators considered 339 known hyperbolic objects, using a computer model to rewind their orbits 100,000 years into the past. Of the fastest incoming objects, they found a cluster from the celestial vicinity of the constellation Gemini; these, they posited, are perhaps locals kicked inward from the outer solar system by a close encounter some 70,000 years ago with nearby Scholz’s star. But Marcos’s team also identified eight possible interstellar interlopers with inbound velocities that seem to stand apart, including 2013’s high-profile Comet ISON.

Like ‘Oumuamua, though, these candidates all dashed into and then out of inner solar system, putting them out of telescope range quickly—and none were studied as objects of potential interstellar origin. “The candidates cited in our work belong to the past, and as such they may not be observed in the future,” Marcos says.

The hope is to inspire other searches in past astronomical surveys to further scrutinize the orbital paths of these candidates or perhaps to find more.

Source: scientificamerican.com
astronomy space
New Horizons Captures Record-Breaking Images in the Kuiper Belt“The routine calibration frame of the “Wishing Well” galactic open star cluster, made by the Long Range Reconnaissance Imager (LORRI) on Dec. 5, was taken when New Horizons was 3.79...

New Horizons Captures Record-Breaking Images in the Kuiper Belt

The routine calibration frame of the “Wishing Well” galactic open star cluster, made by the Long Range Reconnaissance Imager (LORRI) on Dec. 5, was taken when New Horizons was 3.79 billion miles (6.12 billion kilometers, or 40.9 astronomical units) from Earth – making it, for a time, the farthest image ever made from Earth.

New Horizons was even farther from home than NASA’s Voyager 1 when it captured the famous “Pale Blue Dot” image of Earth. That picture was part of a composite of 60 images looking back at the solar system, on Feb. 14, 1990, when Voyager was 3.75 billion miles (6.06 billion kilometers, or about 40.5 astronomical units [AU]) from Earth. Voyager 1’s cameras were turned off shortly after that portrait, leaving its distance record unchallenged for more than 27 years.

LORRI broke its own record just two hours later with images of Kuiper Belt objects 2012 HZ84 and 2012 HE85 – further demonstrating how nothing stands still when you’re covering more than 700,000 miles (1.1 million kilometers) of space each day.

Source: nasa.gov
astronomy new horizons space nasa
ALMA detection and astrobiological potential of vinyl cyanide on Titan“Recent simulations have indicated that vinyl cyanide is the best candidate molecule for the formation of cell membranes/vesicle structures in Titan’s hydrocarbon-rich lakes and...

ALMA detection and astrobiological potential of vinyl cyanide on Titan

Recent simulations have indicated that vinyl cyanide is the best candidate molecule for the formation of cell membranes/vesicle structures in Titan’s hydrocarbon-rich lakes and seas. Although the existence of vinyl cyanide (C2H3CN) on Titan was previously inferred using Cassini mass spectrometry, a definitive detection has been lacking until now. We report the first spectroscopic detection of vinyl cyanide in Titan’s atmosphere, obtained using archival data from the Atacama Large Millimeter/submillimeter Array (ALMA), collected from February to May 2014. We detect the three strongest rotational lines of C2H3CN in the frequency range of 230 to 232 GHz, each with >4σ confidence. Radiative transfer modeling suggests that most of the C2H3CN emission originates at altitudes of ≳200 km, in agreement with recent photochemical models. The vertical column densities implied by our best-fitting models lie in the range of 3.7 × 1013 to 1.4 × 1014 cm−2. The corresponding production rate of vinyl cyanide and its saturation mole fraction imply the availability of sufficient dissolved material to form ~107 cell membranes/cm3 in Titan’s sea Ligeia Mare.

Source: advances.sciencemag.org
astronomy radio astronomy astrobiology
fishmech
astronomyblog

Vega is the brightest star in the constellation of Lyra, the fifth-brightest star in the night sky, and the second-brightest star in the northern celestial hemisphere, after Arcturus. It is relatively close at only 25 light-years from the Sun, and, together with Arcturus and Sirius, one of the most luminous stars in the Sun’s neighborhood.

Image credit: Darren Olley and Masahiro Miysaka

astronomy