Reviewing back…
-Francis Reddy
The observations show there are
massive blobs of dust and gas that occasionally block the star's light, and are
probably spiraling into it. Although there could be other explanations, we
suggest this material may have been produced by the break-up of massive
orbiting bodies near the star. Then a team of U.S. astronomers studying the
star RZ Piscium has found evidence suggesting its strange, unpredictable
dimming episodes may be caused by vast orbiting clouds of gas and dust, the
remains of one or more destroyed planets.
RZ Piscium is located about 550
light-years away in the constellation Pisces. These observations conclude that
RZ Piscium is a young Sun-like star surrounded by a dense asteroid belt, where
frequent collisions grind the rocks to dust. But the evidence was far from
clear. An alternative view suggests the star is instead somewhat older than our
Sun and just beginning its transition into the red giant stage. A dusty disk
from the star's youth would have dispersed after a few million years, so
astronomers needed another source of dust to account for the star's infrared
glow. Because the aging star is growing larger, it would doom any planets in
close orbits, and their destruction could provide the necessary dust.
The team investigated the star using
the European Space Agency's (ESA) XMM-Newton satellite Young stars are often
prodigious X-ray sources. The team’s ground-based observations revealed the
star's surface temperature to be about 9,600 degrees Fahrenheit (5,330 degrees
Celsius), only slightly cooler than the Sun's. They also show the star is
enriched in the tell-tale element lithium, which is slowly destroyed by nuclear
reactions inside stars.
Co-author Joel Kastner, director
of RIT's Laboratory for Multiwavelength Astrophysics said "Our lithium
measurement for RZ Piscium is typical for a star of its surface temperature
that is about 30 to 50 million years old." So while the star is young,
it's actually too old to be surrounded by so much gas and dust. However, The
fact that RZ Piscium hosts so much gas and dust after tens of millions of years
means it's probably destroying, rather than building, planets. Ground-based
observations also probed the star's environment, capturing evidence that the
dust is accompanied by substantial amounts of gas. Based on the temperature of
the dust, around 450 degrees F (230 degrees C), the researchers think most of
the debris is orbiting about 30 million miles (50 million kilometers) from the
star.
The best explanation that
accounts for all of the available data, say the researchers, is that the star
is encircled by debris representing the aftermath of a disaster of planetary
proportions. It's possible the star's tides may be stripping material from a
close substellar companion or giant planet, producing intermittent streams of
gas and dust, or that the companion is already completely dissolved. Another
possibility is that one or more massive gas-rich planets in the system
underwent a catastrophic collision in the astronomically recent past.
by Dini Dwintika Karuniati
16611042
Article Science
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