AAS NOVA — Research Highlights 2018

Find out the latest thinking about our universe.
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A New Look at the Solar Corona

Post by bystander » Sat Sep 22, 2018 3:54 pm

A New Look at the Solar Corona
NOVA | American Astronomical Society | 2018 Sep 21
Kerry Hensley wrote:
The hot, tenuous solar corona is visible during a total solar eclipse, and astronomers have long studied the structure and dynamics of the ghostly coronal streamers. Now, a special observing campaign has allowed us to see the corona in unprecedented detail. ...

The Highly Structured Outer Solar Corona ~ C. E. DeForest et al
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Planning for Images of a Black Hole

Post by bystander » Thu Sep 27, 2018 3:57 pm

Planning for Images of a Black Hole
NOVA | American Astronomical Society | 2018 Sep 24
Susanna Kohler wrote:
In 2006 an ambitious project was begun: creating the world’s largest telescope with the goal of imaging the shadow of a black hole. But how will we analyze the images this project produces? ...

The Event Horizon Telescope (EHT) ...

Principal Component Analysis as a Tool for Characterizing Black Hole Images and Variability ~ Lia Medeiros et al
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JunoCam Captures Dynamics of Jupiter’s Great Red Spot

Post by bystander » Thu Sep 27, 2018 4:03 pm

JunoCam Captures Dynamics of Jupiter’s Great Red Spot
NOVA | American Astronomical Society | 2018 Sep 26
Susanna Kohler wrote:
A camera on the Juno spacecraft has returned stunning high-resolution images of Jupiter’s Great Red Spot. What can we learn about the properties of this long-lived storm? ...

The Rich Dynamics of Jupiter’s Great Red Spot from JunoCam: Juno Images ~ A. Sánchez-Lavega et al
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Unexpected Discovery of a Bright Cow

Post by bystander » Fri Sep 28, 2018 3:48 pm

Unexpected Discovery of a Bright Cow
NOVA | American Astronomical Society | 2018 Sep 28
Susanna Kohler wrote:
The recent discovery of an unusual transient event, nicknamed “the Cow”, has set the community of transient astronomers abuzz (amoo?). What do we know about this odd event so far? ...

The Cow: Discovery of a Luminous, Hot, and Rapidly Evolving Transient ~ S.J. Prentice et al
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Investigating Our Expanding Universe

Post by bystander » Wed Oct 03, 2018 3:58 pm

Investigating Our Expanding Universe
NOVA | American Astronomical Society | 2018 Oct 03
Susanna Kohler wrote:
The universe is expanding — but we’re still not sure how quickly! With past measurements of this expansion rate causing yielding conflict and debate, a new study investigates whether we can resolve the evident tension. ...

The Trouble with Hubble: Local versus Global Expansion Rates in Inhomogeneous
Cosmological Simulations with Numerical Relativity
~ Hayley J. Macpherson et al
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Oscillations in the Eye of the Bull

Post by bystander » Sat Oct 06, 2018 1:49 pm

Oscillations in the Eye of the Bull
NOVA | American Astronomical Society | 2018 Oct 05
Kerry Hensley wrote:
Aldebaran, the brightest star in the constellation Taurus, was one of the first stars suspected to harbor an exoplanet. The presence of its planetary companion, Aldebaran b, was confirmed in 2015, and the decades of data preceding the discovery might harbor a few more surprises. ...

Aldebaran b's Temperate Past Uncovered in Planet Search Data ~ Will M. Farr et al
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Re: Investigating Our Expanding Universe

Post by Ann » Sat Oct 06, 2018 4:46 pm

bystander wrote:
Wed Oct 03, 2018 3:58 pm
Investigating Our Expanding Universe
NOVA | American Astronomical Society | 2018 Oct 03
Susanna Kohler wrote:
The universe is expanding — but we’re still not sure how quickly! With past measurements of this expansion rate causing yielding conflict and debate, a new study investigates whether we can resolve the evident tension. ...

The Trouble with Hubble: Local versus Global Expansion Rates in Inhomogeneous
Cosmological Simulations with Numerical Relativity
~ Hayley J. Macpherson et al
Here's a naive amateur's question. Couldn't the two values be reconciled if the Universe is gradually picking up speed? So that, when we look at the low Planck value of H0, Planck is taking the relatively slow expansion of the young Universe into account, whereas the Hubble value mostly reflects the faster expansion of the local Universe?

Ann
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Re: Investigating Our Expanding Universe

Post by Chris Peterson » Sat Oct 06, 2018 5:45 pm

Ann wrote:
Sat Oct 06, 2018 4:46 pm
bystander wrote:
Wed Oct 03, 2018 3:58 pm
Investigating Our Expanding Universe
NOVA | American Astronomical Society | 2018 Oct 03
Susanna Kohler wrote:
The universe is expanding — but we’re still not sure how quickly! With past measurements of this expansion rate causing yielding conflict and debate, a new study investigates whether we can resolve the evident tension. ...

The Trouble with Hubble: Local versus Global Expansion Rates in Inhomogeneous
Cosmological Simulations with Numerical Relativity
~ Hayley J. Macpherson et al
Here's a naive amateur's question. Couldn't the two values be reconciled if the Universe is gradually picking up speed? So that, when we look at the low Planck value of H0, Planck is taking the relatively slow expansion of the young Universe into account, whereas the Hubble value mostly reflects the faster expansion of the local Universe?
It can all be very confusing. H0 is actually the present value of the Hubble parameter H. H does vary with time, but it is decreasing, not increasing.
Chris

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Ann
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Re: Investigating Our Expanding Universe

Post by Ann » Sat Oct 06, 2018 6:01 pm

Chris Peterson wrote:
Sat Oct 06, 2018 5:45 pm

It can all be very confusing. H0 is actually the present value of the Hubble parameter H. H does vary with time, but it is decreasing, not increasing.
Even though the expansion of the Universe is picking up speed?

Ann
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Re: Investigating Our Expanding Universe

Post by Chris Peterson » Sun Oct 07, 2018 1:51 pm

Ann wrote:
Sat Oct 06, 2018 6:01 pm
Chris Peterson wrote:
Sat Oct 06, 2018 5:45 pm

It can all be very confusing. H0 is actually the present value of the Hubble parameter H. H does vary with time, but it is decreasing, not increasing.
Even though the expansion of the Universe is picking up speed?

Ann
Yes. It has to do with how the parameter is defined can calculated. Like I said, confusing.
Chris

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Cloudbait Observatory
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How to Turn Off a Galaxy’s Star Formation

Post by bystander » Wed Oct 10, 2018 4:53 pm

How to Turn Off a Galaxy’s Star Formation
NOVA | American Astronomical Society | 2018 Oct 08
Susanna Kohler wrote:
New observations by the Atacama Large Millimeter/submillimeter Array (ALMA) provide a close look at a galaxy that may be in the process of shutting down its star formation. ...

Astronomers probe 'outstanding mystery' of how galaxies stop building stars
University of Kansas | 2018 Sep 12

Violent Quenching: Molecular Gas Blown to 1000 km/s during a Major Merger ~ J.E. Geach et al
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Two Explosions with Similar Quirks

Post by bystander » Sat Oct 13, 2018 3:41 pm

Two Explosions with Similar Quirks
NOVA | American Astronomical Society | 2018 Oct 12
Susanna Kohler wrote:
High-energy radiation released during the merger of two neutron stars last year has left astronomers puzzled. Could a burst of gamma rays from 2015 help us to piece together a coherent picture of both explosions? ...

Fermi GBM Observations of GRB 150101B: A Second Nearby Event with a Short Hard Spike and a Soft Tail ~ E. Burns et al
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Puzzles from an Ensemble of Young Planets

Post by bystander » Fri Oct 19, 2018 3:40 pm

Puzzles from an Ensemble of Young Planets
NOVA | American Astronomical Society | 2018 Oct 17
Susanna Kohler wrote:
Blistering hot, giant planets zip around many stars similar to the Sun. New observations of one such planet — likely surrounded by a set of three gas-giant siblings — is now raising questions about the formation of giant planets. ...

High-Resolution Millimeter Imaging of the CI Tau Protoplanetary Disk:
A Massive Ensemble of Protoplanets from 0.1 to 100 au
~ Cathie J. Clarke et al
viewtopic.php?t=38787
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Screening for the Slow Solar Wind

Post by bystander » Tue Oct 23, 2018 2:23 pm

Screening for the Slow Solar Wind
NOVA | American Astronomical Society | 2018 Oct 19
Kerry Hensley wrote:
The solar wind extends outward from the solar corona, suffusing interplanetary space with plasma and magnetic fields. While the solar wind has traditionally been designated as either “fast” or “slow” based on its velocity, a new study suggests that there may be a better way to characterize this highly variable plasma flow. ...

Boundary of the Slow Solar Wind ~ Yuan-Kuen Ko, D. Aaron Roberts, Susan T. Lepri
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Speeding White Dwarfs May Point to Past Explosions

Post by bystander » Fri Oct 26, 2018 9:20 pm

Speeding White Dwarfs May Point to Past Explosions
NOVA | American Astronomical Society | 2018 Oct 24
Susanna Kohler wrote:
A recent study has discovered three of the fastest stars known in the Milky Way. But these stars may be more than just speeders — they might also be evidence of how Type Ia supernovae occur. ...

Three Hypervelocity White Dwarfs in Gaia DR2: Evidence for Dynamically Driven
Double-Degenerate Double-Detonation Type Ia Supernovae
~ Ken J. Shen et al
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Many Small Planets May Hide Close to Low-Metallicity Stars

Post by bystander » Fri Oct 26, 2018 9:31 pm

Many Small Planets May Hide Close to Low-Metallicity Stars
NOVA | American Astronomical Society | 2018 Oct 26
Susanna Kohler wrote:
Our search for worlds beyond our own solar system has revealed thousands of exoplanets in an incredible variety of sizes and configurations. But a new study has revealed that there may be a treasure trove of additional planets hiding where we can’t look as easily: close in around low-metallicity stars. ...

Some Planetary Systems Just Aren't into Heavy Metal
Yale University | 2018 Oct 24

Compact Multi-Planet Systems Are More Common Around Metal-Poor Hosts ~ John M. Brewer et al
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Perfect Blackbodies in the Sky

Post by bystander » Sun Nov 04, 2018 3:44 pm

Perfect Blackbodies in the Sky
NOVA | American Astronomical Society | 2018 Oct 31
Susanna Kohler wrote:
Let’s be honest: nature is messy. Natural forms are complex, and simple models are just approximations — there are no truly spherical cows. And yet … it seems there might actually be some true blackbody stars. ...

Blackbody Stars ~ Nao Suzuki, Masataka Fukugita
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Electrons of the Interstellar Medium

Post by bystander » Thu Nov 08, 2018 5:50 pm

Electrons of the Interstellar Medium
NOVA | American Astronomical Society | 2018 Nov 05
Kerry Hensley wrote:
The behavior of electrons in tenuous interstellar nebulae is up for discussion. What is the best way to describe the energies of electrons in these environments? ...

Electron Energy Distributions in H II Regions and Planetary Nebulae: κ-distributions Do Not Apply ~ B.T. Draine, C.D. Kreisch
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Revisiting Interstellar Asteroid ‘Oumuamua

Post by bystander » Thu Nov 08, 2018 6:18 pm

Revisiting Interstellar Asteroid ‘Oumuamua
NOVA | American Astronomical Society | 2018 Nov 07
Susanna Kohler wrote:
’Oumuamua is back in the headlines again.

When the minor object 1I/2017 ‘Oumuamua was discovered in October of 2017, it was already speeding away from the Sun. ‘Oumuamua’s path, however, quickly identified it not as a solar-system body, but as an asteroid that originated from somewhere beyond our tiny corner of the universe.

Since ‘Oumuamua’s discovery, scientists have scrambled to interpret the bizarre observations of this body. For starters, ‘Oumuamua has an unusual shape: though we have no high-resolution images, light curves suggest that this tumbling asteroid is at least five times as long as it is wide. More recently, however, it’s ‘Oumuamua’s acceleration that has captured the attention of scientists.

Though the asteroid’s trajectory through our solar system was originally assumed to be solely governed by ordinary gravitational forces, recent research suggests that there’s something else at work. ‘Oumuamua’s motion can’t be explained by gravity alone; instead, the asteroid seems to be experiencing an additional acceleration away from the Sun that’s dependent on the Sun–asteroid distance.

What does some of the latest research say about ‘Oumuamua in light of this new development? ...

Spin Evolution and Cometary Interpretation of the Interstellar Minor Object 1I/2017 ‘Oumuamua ~ Roman R. Rafikov Plausible Home Stars of the Interstellar Object 'Oumuamua found in Gaia DR2 ~ C.A.L. Bailer-Jones et al Could Solar Radiation Pressure Explain 'Oumuamua's Peculiar Acceleration? ~ Shmuel Bialy, Abraham Loeb
viewtopic.php?p=287155#p287155
viewtopic.php?t=37911#p279207
viewtopic.php?t=37698
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Clues from an Unexpected Glitch

Post by bystander » Mon Nov 12, 2018 8:05 pm

Clues from an Unexpected Glitch
NOVA | American Astronomical Society | 2018 Nov 09
Susanna Kohler wrote:
Compact objects — the extremely dense remnants left behind after the death of massive stars — continually surprise us with their wide variety of properties and behaviors. Now one compact object known for its stability and predictability has thrown a further hitch into our understanding. ...

The First Glitch in a Central Compact Object Pulsar: 1E 1207.4–5209 ~ E. V. Gotthelf, J. P. Halpern
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A Black Hole X-Ray Binary Rises

Post by bystander » Thu Nov 15, 2018 4:45 pm

A Black Hole X-Ray Binary Rises
NOVA | American Astronomical Society | 2018 Nov 14
Susanna Kohler wrote:
New observations have captured a feeding black hole in our galaxy as it bursts onto the scene. ...

ASASSN-18ey: The Rise of a New Black Hole X-Ray Binary ~ M. A. Tucker et al
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The Origin of Gaps in Protoplanetary Disks

Post by bystander » Sat Nov 17, 2018 3:27 am

The Origin of Gaps in Protoplanetary Disks
NOVA | American Astronomical Society | 2018 Nov 16
Kerry Hensley wrote:
Bright rings and dark gaps are common features in images of protoplanetary disks. How we interpret these features is key to our understanding of how planetary systems form and evolve — so what do these rings and gaps really mean? ...

Rings and Gaps in Protoplanetary Disks: Planets or Snowlines? ~ Nienke van der Marel, Jonathan Williams, Simon Bruderer
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