Sky and Telescope - November 2018 - 9

EXOPLANETS

First Direct Image
of Newborn Planet
ASTRONOMERS USING A NEW instru-

ment on the Very Large Telescope
(VLT) in Chile have directly imaged the
youngest planet known to date. The data
suggest that giant planets come together
quickly and, once formed, regulate further growth of their host star.
The star PDS 70 is only about 5 million years old and is still growing,
accreting mass from a surrounding disk
of gas and dust. Within the gaseous
swirl, researchers had previously found
a dark gap. But while disk gaps are often
taken to be the signature of a newborn
planet, other processes can create gaps,
too (S&T: Oct. 2013, p. 12).
To explore further, Miriam Keppler
(Max Planck Institute for Astronomy,
Germany) and colleagues used VLT's

p The SPHERE instrument on the Very Large
Telescope in Chile imaged PDS 70b after blocking the light from its host star (dark central disk).

SPHERE adaptive optics system, discovering a point source dubbed PDS 70b
within the disk's gap. The astronomers
estimate the object to have an upper
limit of 5-14 Jupiter masses. Revisiting
observations taken in 2012 with the
Gemini South telescope's Near-Infrared
Coronagraphic Imager, the team con-

SUN

POL A R L AY ERED DEPOSITS: ESA / ROSCOSM OS / CASSIS / CC BY-SA 3.0 IGO; R A DA R PROFILE: ESA /
N ASA / JPL / ASI / UNIV. RO ME / R. OROSEI E T A L. 2018; PA RK ER SOL A R PROBE: N ASA / BILL ING A LLS;
NE WBOR N E XOPL A NE T: ESO / A . M ÜLLER E T A L.

Parker Solar Probe Launches to "Touch the Sun"
TOUTED AS THE "mission to touch the
Sun," the Parker Solar Probe is the ﬁrst
to be named after a living person, solar
physicist Eugene Parker (University of
Chicago, emeritus). The spacecraft will
carry a suite of instruments to study
the origin of the solar wind and the
dynamics of the solar corona, looping
around the Sun 24 times in its sevenyear mission.
After its launch on August 12th,
the probe is due to swing by Venus on
September 28th, entering an initial,
150-day-long orbit around the Sun.
Passing 34.7 solar radii from the Sun on
November 1st, it will complete six additional Venus ﬂybys to further decrease
its period to 88 days. Ultimately, the
spacecraft will reach it closest approach,
passing within 9 solar radii of the Sun's
surface, on December 19, 2024.
Engineers designed the Parker Solar
Probe to survive temperatures that
can reach 1600K (2500°F). To take
the heat, the craft is equipped with a
heat shield made of reinforced carbon
composite 11.4 cm (4.5 inches) thick.

The majority of the probe's four instrument suites will remain behind this
shield, where temperatures will be a
comfortable 85°F. But a couple of key
pieces - namely, the Solar Probe Cup
(SPC) and the niobium-alloy antennas
of the FIELDS experiment - will extend
past the shield to directly examine the
Sun. The SPC will scoop up samples of
charged particles in order to measure
their ﬂux and ﬂow, while the FIELDS
experiment will measure the electric
and magnetic ﬁelds around the Sun.
Visit https://is.gd/ParkerSolarProbe
to learn more about the instruments
the probe carries.
The probe will be the ﬁrst mission
to go past the Alfvén point. Within this
boundary, Alfvén waves - oscillations
of charged particles and the magnetic
ﬁelds they travel along - tie the solar
wind to the Sun's surface, but particles
beyond it escape into the solar system.
Studying the plasma within the Alfvén

cludes that PDS 70b orbits its star every
120 years. The result will appear in
Astronomy and Astrophysics.
In a follow-up study to appear in
the same journal, the team went a step
further, taking additional observations
to examine the planet's atmosphere.
Applying several models to the observations, the team found a temperature
in the range of 1000-1600K (1400-
2400°F) and a high likelihood of clouds
of evaporated metals and minerals.
The young planet is still slowly accumulating material, but new observations with the 6.5-m Magellan Clay
Telescope, to be published in Astrophysical Journal Letters by Kevin Wagner
(Steward Observatory) and colleagues,
show that it has probably already
acquired most of its gas. The planet may
have cleared out the wide gap during an
earlier period of runaway gas accretion.
■ JULIE FREYDLIN

point for the ﬁrst time, scientists will
explore the solar wind's origin, hopefully improving space weather forecasts. Close-in measurements will also
help scientists ﬁnd out what heats the
million-degree solar corona.
■ DAVID DICKINSON

u NASA's new solar probe launched August
12th from Cape Canaveral aboard a Delta IV
Heavy rocket.
sk yandtelescope.com * N OV E M B E R 2 018

https://www.is.gd/ParkerSolarProbe http://www.skyandtelescope.com

Sky and Telescope - November 2018

Table of Contents for the Digital Edition of Sky and Telescope - November 2018