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Transcript
Monthly Target List
For Explorations
With MicroObservatory
Each month the sky presents us with a dazzling assortment of spectacular objects on which to train our telescopes: variable stars,
nebulae, galaxies, and clusters of galaxies, to name a few. As the
Earth makes its yearly trip aroundthe Sun, different objects slide into
view in the nighttime sky. Any given object (the Andromeda Galaxy,
for example) is likely to be visible for several months; however, each
potential target has an associated "peak viewing time". This is the
time of year when that object will be at its highest point above the
horizon at the darkest hour, namely midnight. So while it's possible
to take good images of the Andromeda galaxy for much of the fall
and winter, you're likely to get the best images of it in mid-October.
This packet consists of a month-by-month list of some of the most
interesting targets for the MicroObservatory telescopes. The objects
are listed according to the month of their peak viewing opportunities
as described above; in most cases you will be able to get good images
even a couple of months before or after the peak viewing month.
We've also provided some practical information (each object's coordinates on the sky), as well as some of the most exciting current and
historical research tidbits about each target. "Cool Facts" consist of
descriptions of each object, as well as some fascinating properties of
the object. "Connections" are questions which are meant to get you
thinking about conceptual ties to other areas of astronomy, the physical sciences, and sometimes other disciplines. "What's Hot" lists
some of the most exciting cutting-edge research being done with
NASA spaceborne instruments and other telescopes. "Web Resources"
points you to some potentially useful websites for more information.
"People" lists scientists who are doing state-of-the-art work on the
target in question, and who also have an interest in contributing
images and data for the FGU curriculum. "Activities/Challenges"
are suggested ideas for investigations that can be carried out with
the MicroObservatory telescopes, sometimes supplemented with
images and data from the scientific community.
Month
Name of Target
RA
Dec
Cool Facts
Connections
January
Galaxy Group NGC2300
(Agglomeration of galaxies,
gas, and possibly unseen
matter)
07:32.0
+85:43
In visible light, this is a
beautiful group of galaxies.
But there is also an abundance
of invisible searing-hot gas.
What's keeping it from boiling
away? There's got to be
a huge mass of additional
What keeps the Earth's
atmosphere in place?
Why doesn't the Moon
have an atmosphere?
Where does one find other
examples of dark matter in
the Universe? Why is ultra-
dark matter exerting a
gravitational pull on the
visible gas and galaxies
to hold the whole cluster
together. The only way to
"see" the million-degree
gas is in X-rays!
hot gas only detectable in
X-ray light?
February
(visible + X-ray image)
Bode's Galaxy M81
(Spiral Galaxy)
09:55.6
+69:04
This beautiful grand-design
spiral is in close interaction
with its nearby companion,
M82 (see below). The two
galaxies had a close encounter
a few tens of millions of years
ago, leaving some scars on
M81's spiral pattern. In a
billion years or so, the two
galaxies will collide and will
probably merge to form a
single, larger galaxy.
February
Cigar Galaxy M82
(Irregular Galaxy)
09:55.8
+69:41
This somewhat disk-shaped
irregular galaxy recently had
a near-collision with its
neighbor M81 (see above). The
encounter left M82's core disrupted, and triggered a heavy
bout of star formation. In
addition, M82 is the brightest
galaxy in the sky in infrared
light.
March
Galaxy M106
(Spiral Galaxy)
12:19.0
+47:18
Like many galaxies, M106 has
a huge black hole at its center,
tens of millions of times more
massive than our Sun. The
black hole in the nucleus of
M106 was found in 1995 by
astronomers who noticed the
great speeds with which the
gas in the galaxy's center was
swirling around. This was the
very first supermassive black
hole to be definitively discovered.
Think of what you may know
about Kepler's laws as
they work in our own Solar
System. How can we use
information about the orbits
of the planets to figure out
the mass of the Sun? Could
you use a similar technique
to figure out the mass of the
black hole at the center of
M106?
March
The Virgo Cluster
(Cluster of Galaxies)
12:30
+12:30
(approximate center)
The nearest large galaxy
cluster to our own Local Group,
the Virgo Cluster is a spectacular sight, containing over
2000 galaxies, and like
NGC2300 (see above), it also
harbors a large amount of hot,
invisible gas, detectable only
in X-rays. The gravitational
pull of this huge cluster is
large enough that our own
Milky Way and other nearby
galaxies are being noticeably
pulled toward Virgo.
The Virgo Cluster is huge many millions of light years
across! Is there anything
in the Universe that's bigger
than a cluster of galaxies?
What about superclusters?
(Perhaps we ourselves live
in one - how would we know?)
What exactly are the biggest
objects in the Universe?
What's Hot
Web Resources
People
Activities/Challenges
Most of the huge hot gas clouds
out there are found in big galaxy
clusters like the Virgo cluster
(see below). The gas cloud in
NGC2300, discovered by
NASA's ROSAT satellite, was
the first such beast to be seen
chandra.harvard.edu/photo/0087
gcn.gsfc.nasa.gov/~horner/cluster/
Laura Grego at the Center
for Astrophysics in Cambridge has made observations of the hot gas in
galaxy clusters with the
CHANDRA X-ray
telescope.
With the help of information provided by a
scientist, figure out the
total mass needed to hold
all of the galaxies in place.
Now do a similar investigation for the Earth's
in a small galaxy group.
Recently, the Chandra X-ray
telescope looked at another
galaxy cluster, Hydra A,
and found something
extraordinary. Check it
out on the web!
The Hubble Space Telescope
has captured M81 and its
companion M82 in a beautiful
image - check it out on the web!
atmosphere, and for the
Moon. (Time & Motion)
www.seds.org/messier/m/m081.html
antwrp.gsfc.nasa.gov/apod/ap000209.html
www.seds.org/messier/m/m082.html
antwrp.gsfc.nasa.gov/apod/ap000209.html
In 1999 a group of radio
astronomers used an ingenious
technique to pin down the
distance from Earth to M106.
Using observations of the gas
swirling around the central
black hole, they found a
distance of 23.5 million light
years, give or take 1 million.
Believe it or not, this makes
M106 the object with the bestdetermined distance to date
outside our own Galaxy!
www.seds.org/messier/m/m106.html
Lincoln Greenhill at the
Center for Astrohysics has
been involved for several
years with the team that
has been looking at M106
in radio waves. He was
one of the people who
discovered the central
black hole, as well as
figured out the distance
to this galaxy.
Month
Name of Target
RA
Dec
Coll Facts
April
Galaxy M87
(Giant Elliptical Galaxy
in the Virgo Cluster)
12:30.8
+12:40
M87 is the biggest, brightest
galaxy in the nearby Virgo
Cluster. It is orbited by tens
of thousands of globular star
clusters (the Milky Way has
only a couple hundred); it
has a spectacular visible jet
of gas ejected from the
galaxy's core; and, like many
galaxies, it most likely has
a giant black hole at its
center.
April
Galaxy NGC4565
(Edge-On Spiral Galaxy)
12:36.3
+25:59
This is a spectacular example
of a spiral galaxy seen edge-on
(see also NGC891 below).
April
Pinwheel Galaxy M101
(Face-On Spiral Galaxy)
14:03.2
+54:21
This is one of the most stunning
face-on spiral galaxies in the
sky. If current estimates of
its distance are correct, it is
also one of the largest disk
galaxies, with a diameter of
about 170,000 light years.
M101 is probably the beststudied spiral galaxy outside
our own Local Group.
May
Globular Cluster M80
16:17.0
-22:59
This globular cluster contains
hundreds of thousands of stars.
It's fairly low in the sky when
observed from northerly
latitudes, so it's best viewed
around its optimal time of the
year, which is the end of
May.
June
Globular Cluster M13
16:41.7
+36:28
July
Ring Nebula M57
(Planetary Nebula)
18:53.6
+33:02
Globular clusters are among the
oldest objects in the universe some cosmologists' estimates
of the age of the universe itself
are known to be too short
because globular clusters are
older! M13 has at least one
very young star in it, probably
captured recently from elsewhere.
The Ring Nebula is a planetary
nebula, formed when a star
much like our own Sun ended
its life by swelling into a red
giant and then shedding its
outer layers. This nebula emits
most its light at or near a
single wavelength!
Connections
Why do some stars end their
lives looking like the Ring
Nebula, while other more
massive stars die in violent
explosions and leave corpses
like the Crab Nebula (see
below)?
What's Hot
Web Resources
People
Activities/Challenges
www.seds.org/messier/m/m087.html
A team of Japanese astronomers,
using the ASCA satellite, have
looked at NGC4565 in X-rays
and have found two objects
which are probably binary
star systems containing black
holes.
Images taken with the ROSAT
X-ray satellite have revealed
the presence of two remnants
of extremely violent explosions
known as hypernovae. These
explosions are much more powerful than supernovae, and may
be connected to the mysterious
gamma-ray bursts.
www.seds.org/messier/m/m101.html
www.astro.umass.edu/~wqd/hnr/hnr.htm
Images taken of M80 with the
Hubble Space Telescope reveal
that there are lots of younglooking blue stars in this very
old, mostly reddish cluster! It
turns out that these stars only
LOOK young - they're actually
as old as the rest of the cluster,
but probably had their outer
layers stripped off during
close encounters with other
stars.
www.seds.org/messier/m/m80.html
Daniel Wang at the University of Massachusetts
discovered the hypernova
remnants in M101. He
currently has high school
interns working with him
on his research.
www.seds.org/messier/m/m013.html
www.seds.org/messier/m/m057.html
oposite.stsci.edu/pubinfo/pr/97/pn
Take images of the Ring
Nebula using various
filters. In which one does
it appear brightest? Why?
(Light & Color)
Can you find the faint star
at the center?
Month
Name of Target
RA
Dec
Coll Facts
July
Dumbbell Nebula M27
(Planetary Nebula)
19:59.6
+22:43
The Dumbbell is a planetary
nebula like the Ring Nebula
(see above). It's huge - the
faint outer parts cover half as
much sky as the full Moon!
Like the Ring, it shines
almost exclusively in light
emitted by twice-ionized
oxygen.
August
Star HD 209458
(Sun-like Star)
22:03.2
+18:53
This star has a giant, Jupiterlike planet orbiting it at a
distance one-tenth the size
of Mercury's orbit. The planet
was discovered by observing
the "wobble" it induces in the
star's motion.
Connections
Is our own Solar System
typical in its arrangement
and spacing of planets, or
is it unique? Could we "see"
the Earth if we lived on a
planet orbiting a distant
star? Are planets the only
places where life might
develop?
(This picture is an artist's
rendering!)
August
Beta Lyrae
(Eclipsing Binary Star)
18:50.1
+33:22
Beta Lyrae is a star with an
invisible companion, another
star, orbiting it. The primary
star (the one we can see) is
actually having some of its
matter siphoned off into
a swirling disk around the
companion star by its gravity.
When the companion with its
disk passes in front of the
primary star, it causes an
eclipse and the primary star
appears to get dimmer.
October
Andromeda Galaxy M31
(Spiral Galaxy)
00:42.7
+41:16
It's the closest spiral galaxy
to the Milky Way, and by far
the best-studied galaxy
outside our own. It appears
to have two nuclei at its center maybe it swallowed another
galaxy whole at some point
in the past!
How can we learn more about
our own Galaxy by studying
our nearest spiral neighbor?
Will we ever have a view
like this of the Milky Way?
October
Galaxy NGC891
(Edge-On Spiral Galaxy)
02:22.6
+42:21
It's a spiral galaxy much like
our own Milky Way, but you
can't see the spiral arms
because it's oriented edge-on.
You can see a dramatic dark
dust lane down the middle.
A team of Dutch astronomers
recently found huge amounts
of molecular hydrogen in
NGC891 looking in the
infrared - could this be the
"missing mass" in this galaxy?
Why can't you see through
the dust in this galaxy?
Can you seethrough to the
center of our own Milky Way?
What makes something
opaque instead of transparent? Why can you see
through a thick pane of
glass but not through a thin
sheet of paper?
What's Hot
Web Resources
People
Activities/Challenges
www.seds.org/messier/m/m027.html
oposite.stsci.edu/pubinfo/pr/97/pn
Astronomers recently saw the
star get slightly dimmer at
regular intervals - evidence
that the planet is actually
passing in front of the star!
This means that we're seeing
its orbit edge-on, and allowed
astronomers to figure out the
mass of the planet very
accurately.
astron.berkeley.edu/~gmarcy/transit.html
David Charbonneau is a
graduate student at Harvard University who was
on the team that discovered that the planet
passes directly in front
of the star.
Take several images of the
star; can you tell if its
brightness is changing?
Is it doing so at regular
intervals? With some
additional info provided
by a scientist, can you figure
out how large the planet
is? How large the star
is? How large the planet's
orbit is?
The Chandra X-ray
telescope has found strong
evidence for a huge black hole
in the center of M31. It seems
likely that a similar, but much
hotter, beast also lives at the
center of our own galaxy.
www.seds.org/messier/m/m031.html
chandra.harvard.edu/press/00_releases/
press_011400m31.html
ww.skypub.com/sights/northern
users.erols.com/gmqm/arabastro.html
www.auvel.org/zenithco.sufi.html
www.seds.org/messier/xtra/similar/hodierna.html
Michael Garcia is on the
Chandra team which
found the relatively
lukewarm black hole at
the center of M31.
Take an image of M31;
can you see the individual
stars that make up this
galaxy? Can you estimate
how many stars there are
in M31? How large should
an individual star in M31
appear in your image?
(Size & Scale)
Astronomers at NASA's
Goddard Spaceflight Center
are mapping our own Milky
Way galaxy all across the
spectrum, from radio waves
up through gamma rays. Might
our own galaxy harbor large
amounts of molecular hydrogen
as well?
Dave Leisawitz works
with the COBE team at
Goddard, and is involved
in the Multi-Wavelength
Milky Way project.
Month
Name of Target
RA
Dec
Coll Facts
Connections
November
Algol
(Eclipsing Binary Star in
the constellation Perseus)
03:08.2
+40:57
Algol is actually two atars
in orbit around one another one is an ordinary main
sequence star like the Sun, the
other is a huge red giant.
Algol's brightness changes
when the red giant passes
in front of the main sequence
star and blocks its light from
November
The Pleiades, aka M45
(Young Star Cluster)
03:47.0
+24:07
It's a cluster of very young
(only a few million years old)
stars and their associated gas
and dust.
New stars are forming in
our galaxy all the time, and
some are much younger than
our own planet! The Pleaides
weren't even around when
the dinosaurs walked the
Earth.
December
Crab Nebula M1
(Supernova Remnant)
05:34.5
+22:01
It's spectacularly bright at all
wavelengths of light, from
radio waves up through
gamma rays. No other
source in the sky can boast
the same!
The Crab has a rich history
starting with the supernova explosion which
created it in 1054 AD.
December
Orion Nebula M42
(Star-Forming Region)
05:35.4
-05:27
The Orion nebula is a giant
cloud of gas and dust. It's a
fantastic laboratory for
studying how stars like
our Sun are born. It's visible
to the naked eye, in the
belt of the constellation
Orion.
Chemistry: How can we tell
what anything is made of?
Each chemical element and
molecule has a distinct
signature if you know how
to look for it. Where does
the water on Earth originally
come from?
What's Hot
Web Resources
People
Activities/Challenges
www.seds.org/messier/m/m045.html
The Chandra X-ray
telescope resolved the
innermost regions of the
nebula, and may provide
clues as to the nature of the
central generator (pulsar)
that causes the nebula to
shine so brightly.
chandra.harvard.edu/photo/0052
www.seds.org/messier/m/m001.html
super.colorado.edu/~astr1020/sung.html
www.chaco.com/park/archaeology/nebula.html
The SWAS infrared satellite
is looking for signs of the
presence of water and molecular
oxygen in the Orion Nebula.
Water helps gas clouds to cool
and collapse to form stars, so
it's important to know where
water can be found in space.
cfa-www.harvard.edu/cfa/oir/Research/swas.html
www.seds.org/messier/m/m042.html
Figure out how old the Crab
nebula is by comparing
images taken decades apart.
(Time & Motion; Size &
Scale)
René Plume works on the
SWAS satellite, and has
been working closely with
high school students in on
Pittsburgh on some of the
scientific analysis.