ASTRONEWS
WWW.ASTRONOMY.COM 11QUICK TAKES
DOUBLE SCORE
New research suggests
the interstellar asteroid
‘Oumuamua likely came from
a binary star system.- HIGH WATER CONTENT
WASP-39b — a hot, Saturn-
mass exoplanet located
700 light-years from Earth —
contains a surprising amount
of water, roughly three times
as much as Saturn.
NATIONAL TREASURE
McDonald Observatory will
train National Park Service
employees to teach park
visitors about the night sky.
DENSE MATTER
A novel mathematical model
that incorporates quantum
mechanical forces with
general relativity allows for a
new, ultra-compact type of
star similar to a black hole.
WEATHER REPORT•
ARIEL, the world’s first space
telescope dedicated to
studying exoplanetary
atmospheres, will launch in
It will probe planets in
more than 1,000 systems.
KEEPING COOL
Drawing inspiration from the
evaporated salt found on
Ceres’ surface, researchers
are investigating whether
injecting salt into the upper
troposphere could cool Earth.
- SMASH-UP
The rubber duck-shaped Comet
67P may have formed when
two objects catastrophically
collided and reformed within
a matter of days.
NEW DOMAIN
A proposed dark matter detec-
tor would use gallium arsenide
crystals to scan for signals at
energies thousands of times
lower than currently possible.
SIGNAL OUTAGE•
A SpaceX rocket launch carved
a 560-mile-wide (900 kilome-
ters) hole in Earth’s ionosphere
last year, which may have tem-
porarily disrupted GPS signals.- EARLY DAYS
Physicists have developed the
first description of the laws of
thermodynamics for very
small, high-energy particles,
providing insight into the
birth of the universe. — J.P.
IN MEMORIAM. In March, astronomers using the MASTER Global Robotic Net telescopes observed a gamma-ray
burst associated with the birth of a new black hole. They dedicated the discovery to the late Stephen Hawking.About 70,000 years ago, a small star
passed within a light-year of the Sun,
skimming the edge of the Oort Cloud
— the extended shell of over a trillion
icy objects that cocoons the outer
solar system.
Previously, astronomers believed
this wandering star, dubbed Scholz’s
star, passed by relatively peacefully,
influencing few, if any, outer solar
system objects. But new research
suggests the star may have caused
more of a ruckus than we thought.
In a study published February 6
in Monthly Notices of the Royal
Astronomical Society: Letters, scientists
analyzed the orbital evolution of 339
known minor objects (like asteroids
and comets) with hyperbolic orbits
that will eventually usher them out of
the solar system. By winding their
orbits back 100,000 years, the team
was able to estimate the point in the
sky, or radiant, where each body
appears to have come from.
Surprisingly, they found that more
than 10 percent of the objects (36)originated in the direction of the con-
stellation Gemini. This spot in the sky
also happens to be exactly where
astronomers would expect objects to
come from if they were nudged by
Scholz’s star during its close pass.
In addition to finding evidence
that Scholz’s star sent objects tum-
bling from the Oort Cloud, the team
also determined that eight of the
objects they studied — including
Comet ISON (C/2012 S1), Comet
McNaught (C/2009 K5), and therecently identified interstellar visitor
‘Oumuamua (1I/2017 U1) — are travel-
ing so quickly that they are all most
likely interstellar objects zipping
through the solar system.
The results show that astronomers
may not need to wait for interstellar
objects to serendipitously slingshot
around the Sun to study them.
Instead, statistical studies like this
could be used to help astronomers
proactively identify extrasolar visitors
for future analysis. — Jake ParksStellar flyby
shook up outer
solar system
How do neat
piles of boulders
form on Mars?
FALL IN. Planetary scientists planned
to track the movement of sand dunes
near Mars’ north pole using this image
from NASA’s Mars Reconnaissance
Orbiter. But what they discovered
between the dunes was just as
interesting: Inside the parallel dark
stripes that run from upper left to
lower right in this image are piles of
boulders spaced at regular intervals.
The cause? Researchers believe frost
heave — a process that on Earth carries
rocks to the surface and leaves them
in apparently organized piles as the
ground repeatedly freezes and thaws
— is likely the culprit. Such a cycle may
take longer on Mars than on Earth, and
it may be connected to changes in the
Red Planet’s orbit rather than seasonal
cycles, as on Earth. — A.K.Brown dwarfs, called “failed stars”
because they are not massive enough
to fuse hydrogen into helium, start
out hot and cool over time. As its
temperature decreases, a brown
dwarf’s atmosphere also transitions
from cloudy to clear. Researchers led
by Jonathan Gagné at the Carnegie
Institution for Science in Washington,
D.C., now have determined when this
shift in the weather occurs.
The work, published February 16
in The Astrophysical Journal Letters,
contains observations of the brown
dwarf 2MASS J13243553+
(J1324 for short), one of the nearest
such objects to our Sun.
Using measurements of J1324’s
velocity and position, the team first
confirmed that J1324 is part of the
AB Doradus moving group, which
contains around 80 stars all about
150 million years old. Combining this
age with measurements of the brown
dwarf’s distance and luminosity,
they calculated its radius, mass, and
temperature.
J1324 is cloudless, but another
brown dwarf in the same group is still
cloudy. Because the objects are
roughly the same age, their tempera-
ture disparity must be responsible for
the difference, allowing the team to
determine when this change happens.“We were able to constrain the
point in the cool-down process at
which brown dwarfs like J
transition from cloudy to cloud-
free,” Gagné said in a press release.
That temperature is 1,150 kelvins
(1,60 0 degrees Fahrenheit).
Brown dwarfs are similar to gas
giant planets, such as Jupiter.
Knowing how temperature affects
their atmospheres can help astrono-
mers piece together the history and
evolution of our own solar system, as
well as many others. — A.K.Clear skies for cooled brown dwarfs
NOSY NEIGHBOR. When humans were just beginning to migrate out of Africa and
Neanderthals still shared the planet with us, a small, reddish star passed within a light-year
of Earth, likely sending dozens of comets and asteroids tumbling from the outer solar system.CLOUDY CONDITIONS. Brown dwarfs
are larger than planets but too small to
become stars. Their atmospheres transition
from cloudy to cloudless over time, and this
change happens at about 1,150 kelvins for
objects 150 million years old, astronomers
have determined. NASA/JPL-CALTECHNASA/JPL-CALTECH/UNIVERSITY OF ARIZONAJOSÉ A. PEÑAS/SINC