Sky & Telescope - February 2021 - 57

Going Deep by Dave Tosteson

The Newborn Nursery of Orion
Up for a challenge? Point your telescope toward M42 to spot newly born planetary systems.
fecundity in the form of proplyds (from
" ionized protoplanetary disks " ). At a
distance of around 1,300 light-years,
the Orion Nebula is the closest large
stellar birthplace in the night sky. And
some of these proplyds are within the
reach of amateur telescopes.

What Are Proplyds?
In 1979, French astronomers Pierre
Laque and Jean-Louis Vidal discovered
emission line objects they described
as " compact photoionized knots " near
the center of the Orion Nebula. Several years later, radio emissions were
observed from these objects, prompting
speculation that they might be stars
in the process of being born. Hubble
Space Telescope (HST) observations in
1993 conﬁrmed this scenario, and these
knots were recognized as a distinct, new
class of object.
Speciﬁcally, the term proplyd refers
to highly irradiated protoplanetary disks
surrounding newly born stars. They exist
within (or near) an H II region and are
ionized courtesy of nearby hot, young

ESO / M. MCCAUG HRE A N

W

hen we look up into the night
sky each star has its own story,
each is at a different stage in its life. If
we are very fortunate, as with Supernova 1987A, we may ﬁnd ourselves in
the right time and place to witness a
massive star announce the end of its life
with great fanfare. The last supernova
visible to the unaided eye in our own
galaxy was in AD 1604. These events,
albeit rare, require little effort on the
part of the observer. Indeed, some are
hard to miss, such as the AD 1054
supernova that resulted in the Crab

Nebula - that stellar explosion was
visible in daylight for weeks after the
event. Conversely, observing stars at
the beginning of their lives takes great
effort, as they're born shrouded by gas
and dust that obscure our view. Powerful winds from massive nearby stars
can blow away some of the nebulosity
surrounding newborn stars, allowing us
to peer at this otherwise hidden process.
These newborn stars might be sculpting and illuminating nascent planetary
systems. The heart of the Orion Nebula
(M42) harbors such a site of celestial

5h 40m
0°

M78

δ

ε
ζ

5h 20m
Star magnitudes

PLANETARY SYSTEMS IN THE MAKING The famous Trapezium stars at the heart of
the Orion Nebula are at the center of this color-composite image obtained with the Very
Large Telescope (VLT) at the European Southern Observatory's Paranal site. Various
studies have revealed numerous objects that will likely evolve into planetary systems.

η

σ

2
3
4
5
6

M43

-5°

ι

M42

β
τ
Rigel

-10°

κ

ORION

β

λ

S NURSERY IN ORION M42 is easy to locate
in the Sword of the mighty Hunter, Orion.
However, you'll need a big telescope to spot
the embedded newly born planetary systems
known as proplyds.
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Sky & Telescope - February 2021

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