AAS NOVA — Research Highlights 2018

Find out the latest thinking about our universe.
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Searching for Alien Needles in the Cosmic Haystack

Post by bystander » Mon Dec 03, 2018 5:36 pm

Searching for Alien Needles in the Cosmic Haystack
NOVA | American Astronomical Society | 2018 Nov 30
Kerry Hensley wrote:
Humanity’s search for signs of extraterrestrial intelligence has been underway, in one form or another, for decades. But how much searching have we really done? ...

How Much SETI Has Been Done? Finding Needles in the n-Dimensional Cosmic Haystack ~ Jason T. Wright et al
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Exploring the Escaping Atmosphere of HAT-P-11b

Post by bystander » Wed Dec 05, 2018 9:10 pm

Exploring the Escaping Atmosphere of HAT-P-11b
NOVA | American Astronomical Society | 2018 Dec 03
Susanna Kohler wrote:
The atmospheres of planets close to their host stars live a tenuous existence. New observations from the Hubble Space Telescope show signs of a Neptune-like exoplanet’s atmosphere being eroded away. ...

Detection of Helium in the Atmosphere of the Exo-Neptune HAT-P-11b ~ Megan Mansfield et al
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Speeding Electrons in a Solar Jet

Post by bystander » Thu Dec 06, 2018 4:30 pm

Speeding Electrons in a Solar Jet
NOVA | American Astronomical Society | 2018 Dec 05
Susanna Kohler wrote:
How is energy released in explosive events like flares and jets? One of the most likely culprits is magnetic reconnection — but we still have a lot of questions about how this process works. In a recent study, radio observations of the Sun provide us with a closer look. ...

Magnetic Reconnection Null Points as the Origin of Semirelativistic Electron Beams in a Solar Jet ~ Bin Chen et al
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Using Machine Learning to Find Planets

Post by bystander » Sat Dec 08, 2018 3:31 pm

Using Machine Learning to Find Planets
NOVA | American Astronomical Society | 2018 Dec 07
Susanna Kohler wrote:
How do we find the signals of exoplanets lurking in the vast quantity of data that comes out of a mission like Kepler or the Transiting Exoplanet Survey Satellite (TESS)? A new study has some suggestions for how best to get computers to do the heavy lifting for us. ...

Scientific Domain Knowledge Improves Exoplanet Transit Classification with Deep Learning ~ Megan Ansdell et al
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A Jet from Neutron Star Merger GW170817

Post by bystander » Sat Dec 15, 2018 5:15 pm

A Jet from Neutron Star Merger GW170817
NOVA | American Astronomical Society | 2018 Dec 14
Kerry Hensley wrote:
Just last year, the three observatories of the Laser Interferometer Gravitational-Wave Observatory (LIGO)–Virgo Collaboration detected the gravitational-wave signature of two neutron stars colliding. What can we learn from the months of observations made since? ...

A Strong Jet Signature in the Late-time Light Curve of GW170817 ~ K. P. Mooley et al
viewtopic.php?t=37665
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X-Rays from Alpha Centauri

Post by bystander » Mon Dec 24, 2018 12:51 am

X-Rays from Alpha Centauri
NOVA | American Astronomical Society | 2018 Dec 17
Susanna Kohler wrote:
A scientist from University of Colorado Boulder, Tom Ayres, has compiled observations from the Chandra X-ray Observatory tracking the X-ray emission from the two stars of the Alpha Centauri binary system. Alpha Centauri is the closest star system to us, at just 4.37 light-years away.

Alpha Centauri A and B are both Sun-like dwarf stars with coronae very similar to our Sun’s. By studying the X-ray activity of these stars, we can learn more about how stars like the Sun bombard their environments with harsh radiation. This is useful both from the perspective of protecting our own interests — since this so-called space weather can affect astronauts, satellites, our power grid, etc. — and from the perspective of learning about potential habitability around our nearby stellar neighbors. ...

Alpha Centauri Beyond the Crossroads ~ T. R. Ayres
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A New Dim Galaxy Found

Post by bystander » Mon Dec 24, 2018 1:00 am

A New Dim Galaxy Found
NOVA | American Astronomical Society | 2018 Dec 18
Susanna Kohler wrote:
A new low-surface-brightness galaxy has been found within the same field as the lenticular galaxy NGC 2655. This discovery was made by Frederick Steiling and followed up by Dan Crowson, both amateur astronomers and members of the Astronomical Society of Eastern Missouri. The new, dim galaxy is located about 22 arcminutes from NGC 2655.

The last few years has marked a boom in the discovery of extremely dim, faint, diffuse galaxies. By definition, these bodies are at least one magnitude lower in surface brightness than the ambient night sky; they have very few stars and are generally more than 95% non-baryonic dark matter by mass. This makes them excellent laboratories for exploring the properties of dark matter and dark-matter dominated galaxies. ...

Discovery of a Low-surface-brightness Galaxy in the NGC 2655 Field ~ Frederick Steiling, Dan Crowson
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Exploring Planets Beyond Our Galaxy

Post by bystander » Mon Dec 24, 2018 1:07 am

Exploring Planets Beyond Our Galaxy
NOVA | American Astronomical Society | 2018 Dec 19
Susanna Kohler wrote:
Two scientists from University of Oklahoma, Xinyu Dai and Eduardo Guerras, have discovered a population of free-floating planets beyond our own galaxy. They achieved this by analyzing the microlensing of a background, bright, supermassive black hole in Chandra X-ray Observatory images.

If Dai and Guerras’s models and interpretations are correct, then this marks the first time we’ve ever discovered planets outside of our own galaxy. If these unbound planets in the lensing galaxy are Moon- to Jupiter-sized, the authors’ models suggest a population of about 2,000 planets per main-sequence star in the lens galaxy — all of which lie 3.8 billion light-years away from us. ...

Probing Planets in Extragalactic Galaxies Using Quasar Microlensing ~ Xinyu Dai, Eduardo Guerras
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Revival of a Magnetar

Post by bystander » Mon Dec 24, 2018 1:18 am

Revival of a Magnetar
NOVA | American Astronomical Society | 2018 Dec 20
Susanna Kohler wrote:
A ultra-magnetized neutron star that has been quiescent for three years has now reawakened, according to a study led by Fernando Camilo (SKA South Africa). New radio and X-ray observations of the magnetar PSR J1622–4950 reveal pulses of radiation from this source for the first time since 2014.

Unlike pulsars, which are neutron stars with emission powered by the decay of their rotation, magnetars are neutron stars powered by the decay of their extremely strong magnetic fields. Of the nearly two dozen confirmed magnetars, only four have been discovered to exhibit radio pulses in addition to X-rays — and J1622–4950 is one of them. Exploring this source is therefore important for understanding the physics at work, as well as the similarities and differences between magnetars and pulsars. ...

Revival of the Magnetar PSR J1622–4950: Observations with
MeerKAT, Parkes, XMM-Newton, Swift, Chandra, and NuSTAR
~ F. Camilo et al
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Discovery of Dark Galaxies

Post by bystander » Mon Dec 24, 2018 1:25 am

Discovery of Dark Galaxies
NOVA | American Astronomical Society | 2018 Dec 21
Susanna Kohler wrote:
A team of scientists led by Raffaella Marino (ETH Zürich, Switzerland) have used the Multi Unit Spectroscopic Explorer (MUSE) instrument at ESO’s Very Large Telescope to discover six candidate “dark galaxies”, galaxies that contain a large amount of gas but don’t yet contain any stars.

We still don’t fully understand what the fuel for the first stars in the universe was — how did the diffuse intergalactic medium first come together to trigger star formation in early galaxies? One theory is that there was an epoch in the early phase of galaxy formation during which galaxies were gas-rich but still inefficient at forming stars. By discovering signs of these dark galaxies in the early universe, Marino and collaborators have added supporting evidence to this theory. ...

Dark Galaxy Candidates at Redshift ~3.5 Detected with MUSE ~ Raffaella Anna Marino et al
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Using Lasers to Talk to ET

Post by bystander » Sun Dec 30, 2018 7:11 pm

Using Lasers to Talk to ET
NOVA | American Astronomical Society | 2018 Dec 26
Susanna Kohler wrote:
Could we communicate with distant extraterrestrial intelligence using lasers? Two scientists from the Massachusetts Institute of Technology, James Clark and Kerri Cahoy, have determined that we could produce a detectable laser signal out to 20,000 light-years using current or near-term technology.

The challenges of communicating with hypothesized life beyond our solar system are numerous. One of the most fundamental questions is whether we are technologically capable of producing a strong signal that could be easily detected at large distances. In their feasibility study, Clark and Cahoy show that we can — and, moreover, that such a signal could have a broad enough beam that we could target nearby exoplanets with uncertain orbits (like the planet Proxima Centauri b) or the entire habitable zones of more distant systems (like the TRAPPIST-1 system). ...

Optical Detection of Lasers with Near-term Technology at Interstellar Distances ~ James R. Clark, Kerri Cahoy
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Pinning Down Our Expanding Universe

Post by bystander » Sun Dec 30, 2018 7:16 pm

Pinning Down Our Expanding Universe
NOVA | American Astronomical Society | 2018 Dec 27
Susanna Kohler wrote:
Recent Gaia-measured parallaxes and Hubble photometry of 50 Milky-Way Cepheid variable stars — pulsating stars used as yardsticks to measure cosmic distances — have provided the most precise measurement yet of the local rate of expansion of our universe.

Since astronomers first discovered the universe is expanding, there has been tension between the observed local rate of expansion (which is measured by tracking the distances to and recession speeds of objects around us) and the expansion rate inferred for the early universe (which is derived from observations of the cosmic microwave background). The new and more precise local measurements, made by a team of astronomers led by Adam Riess (Space Telescope Science Institute and Johns Hopkins University), increases that tension further. ...

Milky Way Cepheid Standards for Measuring Cosmic Distances and
Application to Gaia DR2: Implications for the Hubble Constant
- Adam G. Riess et al
viewtopic.php?t=38507
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Identifying Exoplanets with Deep Learning

Post by bystander » Sun Dec 30, 2018 7:25 pm

Identifying Exoplanets with Deep Learning
NOVA | American Astronomical Society | 2018 Dec 28
Susanna Kohler wrote:
Using machine learning, Google Brain engineer Christopher Shallue and NASA Sagan Postdoctoral Fellow Andrew Vanderburg (The University of Texas at Austin, Harvard-Smithsonian CfA) have discovered two new planets within previously known Kepler multi-planet systems.

In today’s field of exoplanet astronomy, observatories like Kepler and TESS have guaranteed us plenty of data. But the transit signal of an Earth-sized planet around a Sun-like star remains at the edge of detectability, and our best bet for reliably picking such signals out of the noise is automation. Shallue and Vanderburg’s study demonstrates the power of training a deep convolutional neural network to identify planet signals in data like Kepler’s. ...

Identifying Exoplanets with Deep Learning: A Five-planet Resonant Chain around
Kepler-80 and an Eighth Planet around Kepler-90
~ Christopher J. Shallue, Andrew Vanderburg
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Looking for the Shadow of Our Galaxy’s Black Hole

Post by bystander » Mon Dec 31, 2018 8:20 pm

Looking for the Shadow of Our Galaxy’s Black Hole
NOVA | American Astronomical Society | 2018 Dec 31
Susanna Kohler wrote:
Radio observations of the supermassive black hole at the center of the Milky Way have reached their highest resolution yet, teasing out details of the structure of Sagittarius (Sgr) A* on a scale of just ~30 microarcseconds. This corresponds to a size of only ~3 times that of the black hole’s event horizon (the distance at which not even light can escape).

By observing our galaxy’s ~4-million-solar-mass black hole, Sgr A*, in unprecedented detail at radio wavelengths, astronomers hope to explore the structure of a supermassive black hole’s event horizon and learn about the physical processes that occur there. The observations presented in this study, led by Ru-Sen Lu (Max Planck Institute for Radio Astronomy, Germany; MIT Haystack Observatory), represent important advancement toward that goal, and they provide an tantalizing glimpse of Sgr A* that is thus far consistent with the picture of ring-like structure that is predicted for the black hole’s event horizon. ...

Detection of Intrinsic Source Structure at ~3 Schwarzschild Radii
with Millimeter-VLBI Observations of Sagittarius A*
~ Ru-Sen Lu et al
Know the quiet place within your heart and touch the rainbow of possibility; be
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