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Johns Hopkins Scientist Proposes New Definition of a Planet « News from The Johns Hopkins University
http://releases.jhu.edu/2018/01/22/johns-hopkins-scientist-proposes-new-definition-of-a-planet/

Pluto hogs the spotlight in the continuing scientific debate over what is and what is not a planet, but a less conspicuous argument rages on about the planetary
status of massive objects outside our solar system. The dispute is not just about semantics, as it is closely related to how giant planets like Jupiter form.

Johns Hopkins University astrophysicist Kevin Schlaufman aims to settle the dispute.

In a paper just published in the Astrophysical Journal, Schlaufman has set the upper boundary of planet mass between four and 10 times the mass of the planet Jupiter.

[1801.06185] Evidence of an Upper Bound on the Masses of Planets and its Implications for Giant Planet Formation
https://arxiv.org/abs/1801.06185

Schlaufman, an assistant professor in the university’s Department of Physics & Astronomy, says setting a limit is possible now mainly due to improvements in the technology
and techniques of astronomical observation. The advancements have made it possible to discover many more planetary systems outside our solar system and therefore possible
to see robust patterns that lead to new revelations.

“While we think we know how planets form in a big picture sense, there’s still a lot of detail we need to fill in,” Schlaufman said. “An upper boundary on the masses of
planets is one of the most prominent details that was missing.”

The conclusions in the new paper are based on observations of 146 solar systems, systems, Schlaufman said, is the fact that almost all the data he used was measured in
a uniform way. The data are more consistent from one solar system to the next, and so more reliable.

Defining a planet, distinguishing it from other celestial objects, is a bit like narrowing down a list of criminal suspects. It’s one thing to know you’re looking for
someone who is taller than 5-foot-8, it’s another to know your suspect is between 5-foot-8 and 5-foot-10.

In this instance, investigators want to distinguish between two suspects: a giant planet and a celestial object called a brown dwarf. Brown dwarfs are more massive than
planets, but less massive than the smallest stars. They are thought to form as stars do.

For decades brown dwarfs have posed a problem for scientists: how to distinguish low-mass brown dwarfs from especially massive planets? Mass alone isn’t enough to tell
the difference bzween the two, Schlaufman said. Some other property was needed to draw the line.

In Schlaufman’s new argument, the missing property is the chemical makeup of a solar system’s own sun. He says you can know your suspect, a planet, not just by his size,
but also by the company he keeps. Giant planets such as Jupiter are almost always found orbiting stars that have more iron than our sun. Brown dwarfs are not so discriminating.

Scientists find evidence of strong winds outside black holes
https://www.folio.ca/scientists-find-evidence-of-strong-winds-outside-black-holes/

New research shows the first evidence of strong winds around black holes throughout bright outburst events in which black holes rapidly consume mass.

The study sheds new light on how mass transfers to black holes and how they can affect the environment around them.

“Winds must blow away a large fraction of the matter a black hole could eat,’’ said Bailey Tetarenko, a University of Alberta PhD student and lead author
on the study. “In one of our models, the winds removed 80 per cent of the black hole’s potential meal.”

The research was conducted by an international team of researchers, led by Tetarenko and scientists in the U of A's Department of Physics.

A ‘hot Jupiter’ with unusual winds | Newsroom - McGill University
http://www.mcgill.ca/newsroom/channels/news/hot-jupiter-unusual-winds-284028

The hottest point on a gaseous planet near a distant star isn’t where astrophysicists expected it to be –
a discovery that challenges scientists’ understanding of the many planets of this type found in solar systems outside our own.

Unlike our familiar planet Jupiter, so-called hot Jupiters circle astonishingly close to their host star -- so close that it typically takes fewer than three days to complete an orbit.
And one hemisphere of these planets always faces its host star, while the other faces permanently out into the dark. Not surprisingly, the “day” side of the planets gets vastly hotter
than the night side, and the hottest point of all tends to be the spot closest to the star. Astrophysicists theorize and observe that these planets also experience strong winds blowing
eastward near their equators, which can sometimes displace the hot spot toward the east.

In the mysterious case of exoplanet CoRoT-2b, however, the hot spot turns out to lie in the opposite direction: west of center. A research team led by astronomers at McGill University’s
McGill Space Institute (MSI) and the Institute for research on exoplanets (iREx) in Montreal made the discovery using NASA’s Spitzer Space Telescope. Their findings are reported Jan. 22
in the journal Nature Astronomy.

A New Bound on Axionssu201802 | www.cfa.harvard.edu/
https://www.cfa.harvard.edu/news/su201802

CfA astronomer Paul Nulsen and his colleagues used a novel method to investigate the nature of axions. Quantum mechanics constrain axions, if they exist, to interact with light in the presence of a magnetic field.
As they propagate along a strong field, axions and photons should transmute from one to the other other in an oscillatory manner. Because the strength of any possible effect depends in part on the energy of the photons,
the astronomers used the Chandra X-ray Observatory to monitor bright X-ray emission from galaxies. They observed X-rays from the nucleus of the galaxy M87, which is known to have strong magnetic fields, and which (at
a distance of only fifty-three million light-years) is close enough to enable precise measurements of variations in the X-ray flux. Moreover, M87 lies in a cluster of galaxies, the Virgo cluster, which should insure
the magnetic fields extend over very large scales and also facilitate the interpretation. Not least, M87 has been carefully studied for decades and its properties are relatively well known.

The search did not find the signature of axions. It does, however, set an important new limit on the strength of the coupling between axions and photons, and is able to rule out a substantial fraction of the possible
future experiments that might be undertaken to detect axions. The scientists note that their research highlights the power of X-ray astronomy to probe some basic issues in particle physics, and point to complementary
research activities that can be undertaken on other bright X-ray emitting galaxies.

Update on an Interstellar Asteroid
http://aasnova.org/2018/01/19/update-on-an-interstellar-asteroid/

Are we sure ‘Oumuamua didn’t originate in our solar system and get scattered into a weird orbit? Jason Wright (The Pennsylvania State University)
demonstrates via a series of calculations that no known solar system body could have scattered ‘Oumuamua onto its current orbit — nor could any as
yet unknown object bound to our solar system.

Eric Mamajek (Caltech and University of Rochester) shows that the kinematics of ‘Oumuamua are consistent with what we might expect of interstellar
field objects, though he argues that its kinematics suggest it’s unlikely to have originated from many of the nearest stellar systems.

https://www.nasa.gov/feature/jpl/asteroid-2002-aj129-to-fly-safely-past-earth-february-4

Asteroid 2002 AJ129 will make a close approach to Earth on Feb. 4, 2018 at 1:30 p.m. PST (4:30 p.m. EST / 21:30 UTC). At the time of closest approach,
the asteroid will be no closer than 10 times the distance between Earth and the Moon (about 2.6 million miles, or 4.2 million kilometers).

2002 AJ129 is an intermediate-sized near-Earth asteroid, somewhere between 0.3 miles (0.5 kilometers) and 0.75 miles (1.2 kilometers) across. It was discovered
on Jan. 15, 2002, by the former NASA-sponsored Near Earth Asteroid Tracking project at the Maui Space Surveillance Site on Haleakala, Hawaii. The asteroid’s
velocity at the time of closest approach, 76,000 mph (34 kilometers per second), is higher than the majority of near-Earth objects during an Earth flyby.
The high flyby velocity is a result of the asteroid’s orbit, which approaches very close to the Sun -- 11 million miles (18 million kilometers). Although asteroid
2002 AJ129 is categorized as a Potentially Hazardous Asteroid (PHA), it does not pose an actual threat of colliding with our planet for the foreseeable future.

Comet Discoverer Thomas Bopp (1949–2018) - Sky & Telescope
http://www.skyandtelescope.com/astronomy-news/people-places-and-events/thomas-bopp-1949-2018/

An unassuming amateur astronomer forever linked to one of the greatest comets in modern history has passed away.

Thomas Joel Bopp, the co-discoverer of Comet Hale-Bopp, died January 5, 2018, in Phoenix, Arizona, from liver cancer. He was 68 years old.

If you live in the western part of North America, Alaska, and the Hawaiian islands,
you might set your alarm early the morning of Wednesday, Jan. 31 for a lunar trifecta: a pre-dawn “super blue blood moon.”

https://www.nasa.gov/feature/super-blue-blood-moon-coming-jan-31

https://www.nasa.gov/...goddard/2018/nasa-team-studies-middle-aged-sun-by-tracking-motion-of-mercury

Like the waistband of a couch potato in midlife, the orbits of planets in our solar system are expanding. It happens because the Sun’s gravitational grip gradually weakens as
our star ages and loses mass. Now, a team of NASA and MIT scientists has indirectly measured this mass loss and other solar parameters by looking at changes in Mercury’s orbit.

The new values improve upon earlier predictions by reducing the amount of uncertainty. That’s especially important for the rate of solar mass loss, because it’s related to
the stability of G, the gravitational constant. Although G is considered a fixed number, whether it’s really constant is still a fundamental question in physics.

https://www.forbes.com/...interstellar-visitor-oumuamua-was-shaped-by-cosmic-particles/#13fcfd497422

Last year, the interstellar interloper ʻOumuamua passed through the inner Solar System. Originally thought to be a comet, then later an asteroid, this visitor turned out to have properties
unlike any object ever seen before. It moved far too quickly and from too inclined an angle to originate from within our Solar System; neither Jupiter nor Neptune nor an Oort cloud object
could have flung it inwards with those properties. When we examined it in detail, it appeared to have a carbon-based coating over an icy interior, yet sprouted no tail, despite reaching
temperatures of 550 °F (290 °C). Oddest of all, it was cigar-shaped, approximately eight times as long as it was wide. While many origin theories have been proposed, an incredibly simple
possibility may provide all the answers: simply traveling through the Milky Way for billions of years may have transformed it into the object we see today.