Transcript observingnebulaeclusters-1

Spring 2012 Astronomy Course
Mississippi Valley Night Sky Conservation
The Sky Around Us
Program developed by
Mississippi Valley
Conservation Authority
Royal Astronomical Society
of Canada
Ottawa Astronomy Friends
Instructors:
Pat Browne
Stephen Collie
Rick Scholes
Earth Centered Universe
software for illustrations –
courtesy David Lane
Observing nebulousity In Clusters in the western
sky
Past the near
objects, the
planets, and
beyond the
double and
variable stars is
a special realm.
Here are the star
clusters, gas
clouds and star
nurseries.
Open Clusters looking West (setting)
( Spring time Northern Hemisphere)
WHERE
Locating Nebulae in Clusters
Observing nebulousity around individual
stars
WHEN
Are they Visible?
Observing (Winter) nebula in the Spring
Western Sky – early evening!
WHAT
Types of Nebulae
Open Clusters and their Nebulae –
Reflection Nebulae
Groups of Stars embedded within a
hydrogen cloud – Emission Nebula
WHERE: > 500 light years
(M42 is located at a distance of 1344 ± 20
light years and is the closest region of
massive star formation to Earth.)
This is much further out than…
Nearest and Brightest stars 5-15 light years
Consider: Lecture 1,II – Stars on the
celestial sphere < 500 light years
Famous Examples:
Pleiades – Reflection Nebula
M42 trapezium – Emission Nebula
Levy 1 (NGC 1931) Reflection/Emission
Nebula
M78 – Reflection Nebula
Orion Nebula M42 - Closeup
"Flying" into the Orion Nebula This animation was
produced by Walt Feimer
in the Astronomy Visualization Laboratory at the
Space Telescope Science Institute. It begins with a
"backyard" view of the sky around the constellation
Orion (by Skip Westphal, STScI) and a more
detailed view of the Orion Nebula, M42 . Images
taken with the 4-meter telescope at Kitt Peak
National Observatory.
A spectacular cloud of gas surrounds several very
hot stars in the star cluster deep within the nebula.
The nebula's constituent gases include hydrogen,
helium, oxygen, carbon, neon, nitrogen, sulphur,
argon, and chlorine; the density of these gases is
above the critical limit required for stars to form
within the nebula.
Visible to the naked eye as the middle "star" in the
"sword" of the constellation Orion, the nebula is
located 1500 light years from Earth.
A closer image taken with the Wide Field Planetary
Camera 2 aboard the Hubble Space Telescope
(C.R. O'Dell, Rice University) provides a more
detailed view of the Nebula.
The final sequence, from details of the HST image,
show several protoplanetary disks or "proplyds" and
finally a single dark disk surrounding a central star.
Reflection Nebula in Young Star
Clusters
For most purposes it can be assumed that
the stars in a given cluster formed
simultaneously from the same parent cloud
of gas and dust. When comparing star clusters,
we oftennote the density of stars, their age
and their chemical composition
(as revealed by their spectra ).
Young Star clusters also often exhibit nebulous
trails of gas and dust which emanate from
members that are still in the process
of becoming stars! Also, those young stars
often continue to radiate and reflect off of
the dusty lanes that mark their birth into the
cluster.
Photographically, and with spectral analysis, we
can see that the blue nebulousity is reflected light
off of the hot young stars
The red nebulousity is due to emission of light
emanating from hot hydrogen clouds…
M78 is the brightest diffuse reflection
nebula of a group of nebulae that include
NGC 2064, NGC 2067 and NGC 2071.
This group belongs to the Orion
Molecular Cloud Complex and is about
1,600 light years distant from Earth. M78
is easily found in smal ltelescopes as a
hazy patch and involves two stars of
10th magnitude. responsible for making
the cloud of dust in M78 visible by
reflecting their light.
Observe:
Catalogue Name
------------------------------M42 Great Orion Nebula – Emission and Reflection
M78 Reflection Nebula (Orion)
M45 – Pleiades (the 7 sisters) - the stars dominate
Levy 1 – Auriga NGC 1931 The nebulousity dominates… reflected off of gas and dust
Levy 1 NGC 1931
M78
M42
M45