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A New Look at the Solar Corona
Posted: Sat Sep 22, 2018 3:54 pm
by bystander
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
Planning for Images of a Black Hole
Posted: Thu Sep 27, 2018 3:57 pm
by bystander
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
JunoCam Captures Dynamics of Jupiter’s Great Red Spot
Posted: Thu Sep 27, 2018 4:03 pm
by bystander
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
Unexpected Discovery of a Bright Cow
Posted: Fri Sep 28, 2018 3:48 pm
by bystander
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
Investigating Our Expanding Universe
Posted: Wed Oct 03, 2018 3:58 pm
by bystander
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
Oscillations in the Eye of the Bull
Posted: Sat Oct 06, 2018 1:49 pm
by bystander
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
Re: Investigating Our Expanding Universe
Posted: Sat Oct 06, 2018 4:46 pm
by Ann
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 H
0, 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
Re: Investigating Our Expanding Universe
Posted: Sat Oct 06, 2018 5:45 pm
by Chris Peterson
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 H
0, 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. H
0 is actually the
present value of the Hubble parameter H. H does vary with time, but it is decreasing, not increasing.
Re: Investigating Our Expanding Universe
Posted: Sat Oct 06, 2018 6:01 pm
by Ann
Chris Peterson wrote: ↑Sat Oct 06, 2018 5:45 pm
It can all be very confusing. H
0 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
Re: Investigating Our Expanding Universe
Posted: Sun Oct 07, 2018 1:51 pm
by Chris Peterson
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. H
0 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.
How to Turn Off a Galaxy’s Star Formation
Posted: Wed Oct 10, 2018 4:53 pm
by bystander
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
Two Explosions with Similar Quirks
Posted: Sat Oct 13, 2018 3:41 pm
by bystander
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
Puzzles from an Ensemble of Young Planets
Posted: Fri Oct 19, 2018 3:40 pm
by bystander
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
Screening for the Slow Solar Wind
Posted: Tue Oct 23, 2018 2:23 pm
by bystander
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
Speeding White Dwarfs May Point to Past Explosions
Posted: Fri Oct 26, 2018 9:20 pm
by bystander
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
Many Small Planets May Hide Close to Low-Metallicity Stars
Posted: Fri Oct 26, 2018 9:31 pm
by bystander
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
Perfect Blackbodies in the Sky
Posted: Sun Nov 04, 2018 3:44 pm
by bystander
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
Electrons of the Interstellar Medium
Posted: Thu Nov 08, 2018 5:50 pm
by bystander
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
Revisiting Interstellar Asteroid ‘Oumuamua
Posted: Thu Nov 08, 2018 6:18 pm
by bystander
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
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Clues from an Unexpected Glitch
Posted: Mon Nov 12, 2018 8:05 pm
by bystander
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
A Black Hole X-Ray Binary Rises
Posted: Thu Nov 15, 2018 4:45 pm
by bystander
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
The Origin of Gaps in Protoplanetary Disks
Posted: Sat Nov 17, 2018 3:27 am
by bystander
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
A Home for Another Fast Radio Burst
Posted: Thu Nov 22, 2018 3:33 pm
by bystander
A Home for Another Fast Radio Burst
NOVA | American Astronomical Society | 2018 Nov 19
Susanna Kohler wrote:
What causes fast radio bursts? Scientists are still hunting for the answer to this question — but the discovery of one burst’s nearby home may bring us a little closer to a solution. ...
A Search for the Host Galaxy of FRB 171020 ~ Elizabeth K. Mahony
et al
The Shape of Cosmic Dawn
Posted: Thu Nov 22, 2018 3:41 pm
by bystander
The Shape of Cosmic Dawn
NOVA | American Astronomical Society | 2018 Nov 21
Susanna Kohler wrote:
In March of this year, a team of scientists announced an unprecedented radio detection: a signal from the first stars that formed in the universe. But the shape of this signal was not quite what we predicted — and theorists are now exploring what this means about the dawn of the universe. ...
Implication of the Shape of the EDGES Signal for the 21 cm Power Spectrum ~ Alexander A. Kaurov
et al
Simulating WFIRST’s Search for Supernovae
Posted: Mon Dec 03, 2018 5:29 pm
by bystander
Simulating WFIRST’s Search for Supernovae
NOVA | American Astronomical Society | 2018 Nov 28
Susanna Kohler wrote:
New exoplanets, distant galaxies, unexpected transients — the successful discoveries of major astronomical missions get splashed across news headlines. What generally isn’t seen, however, is the often decades-long development process that led to these successful missions — a process that includes not only technology and engineering feats, but also the meticulous planning necessary to optimize the use of an observatory with a limited lifetime.
Want a closer look? A recently published study provides an insider’s view of these complex planning stages for a proposed upcoming mission, the Wide Field Infrared Survey Telescope (WFIRST). ...
Simulations of the WFIRST Supernova Survey and Forecasts of Cosmological Constraints ~ R. Hounsell
et al