Transcript M82 - University of Manitoba

Credit: NASA, ESA and the Hubble Heritage Team STScI/AURA). Acknowledgment: J.
Gallagher (University of Wisconsin), M. Mountain (STScI) and P. Puxley (NSF).
M82, located in Ursa Major, was first
discovered by Johann Elert Bode in 1774.
 Its classified as a prototype Starburst Galaxy
of the second type, famous for its heavy
star formation due to its close encounter
with its neighbouring galaxy M81.
 M82 is five times as bright as the entire milky
way galaxy, and 100 times as bright as the
Mily Way’s center, although only about a
quarter of its size.

Distance to Object: 11.5 +- 0.8 Mly
 Size :

› 10.47’ x 4.365’ (Angular Size)
›
(Physical Size)
Apparent Magnitude : 9.3
 Position:

› (J200) RA: 09h 55m 52.2s D: +69° 40′ 47″


First locate the big dipper. The next step is to draw an
imaginary line from gamma Ursae Majoris to alpha Ursae
Majoris, then double its length in the same direction.
Doing this alone, you will most probably locate M81 as a
very faint patch of light. M82 is located close by and is
generally harder to locate as it has a low magnitude. This
method may be summarized by the following diagram.
Backyard Astro. 2009. Deepsky Top-100 (10): M 81 & M82. http://www.backyard
astro.com/deepsky/top100/10.html








In X-ray
Chandra Telescope.
Credit NASA/SAO/G.Fabbi
ano et al.
Scale Image is 5 arcmin
across.
Release Date June 05,
2001
Red = low energy, green
intermediate, and blue
high-energy X-rays. White
and yellow sources emit
both low- and high-energy
X-rays
Observation Time 13 hours
Observation
Dates September 20, 1999
The bright spots in the center are
Supernova remnants or X-ray binaries.
Observing M82 in the Infrared spectrum, it
is the brightest galaxy in the sky.
Frommert H, Kronberg C. 1998. The Messier
Catalogue.
http://seds.lpl.arizona.edu/Messier/more/m0
82_cxo.html

Scale: 7.9 arcmins ac ross

Telescope : Spitzer Telescope

Image Credit: NASA/JPL-Caltech/C.
Engelbracht (University of Arizona)







Instrument: IRAC
Wavelength: Infrared: Red
Exposure Date: May 6, May 8, and May 9
2005
Exposure Time: 4 minutes per point, 1
hour for full image
Field of View: 12.6 x 12.6 arcminutes
Orientation: North is 57.7 deg counter
clockwise from up
Release Date: 16 March 2006
Chandrea X-ray Observatory. 2008.
http://chandra.harvard.edu/photo/2006/m
82/more.html
This picture was
taken with a
combination of
telescopes: the VLA
in New Mexico, and
the MERLIN in the UK
 The reason behind
the three distinct
maxima is most
widely described by
the presence of UVabsorbing dust
covering its nucleus.

Frommert H, Kronberg C. 1998. The Messier
Catalogue.
http://www.seds.org/messier/more/m082_uit.
html
The image is
in false colour
 The dust
covering the
galaxies core
is still visible,
however, not
as prominent
as with the
UV image
taken with
the same
telescope

Frommert H, Kronberg C. 1998. The Messier Catalogue.
http://www.seds.org/messier/more/m082_uit.html







Credit: X-ray:
NASA/CXC/JHU/D.Strickland
; Optical:
NASA/ESA/STScI/AURA/The
Hubble Heritage Team; IR:
NASA/JPL-Caltech/Univ. of
AZ/C. Engelbracht
Scale: Image is 7.9 arcmin
across
Observation Dates: June 18,
2002
Observation Time: 5 hours
Color Code Energy : (X-ray:
Blue; Optical: Green &
Orange; Infrared: Red)
Instrument : ACIS
Release Date: April 24, 2006
Chandrea X-ray Observatory. 2008.
http://chandra.harvard.edu/photo/2006/m
82/more.html
A starburst galaxy is a galaxy in which there is
an abnormal amount of star creation.
 Two main types of Starburst Galaxies:

› Blue Compact Galaxies
 Contain low amounts of mass, metallicity, and dust,
and contain a large amount of hot young stars.
 Radiate in the UV spectrum
› Ultra-luminous Infrared Galaxies
 Generally extremely dusty.
 Seen in the infrared. The UV light emitted from the hot
young stars is absorbed and reemitted as infrared by
the dust flooding the galaxy.
 The center of a ULIRG can be seen in the X-ray
spectrum.


In order to create a Starburst Galaxy, there
must be present a large supply of gas to form
large amounts of new stars. This large amount
of gas must undergo compression through tidal
forces triggered by a close encounter or
collision with another nearby galaxy
M82’s high level of star formation is due to a
close encounter with its neighbouring galaxy
M81. The interaction is evident through
discovery of large streams of neutral hydrogen
connecting the two galaxies seen in the radio
spectrum.



Far-UV imaging of the starburst galaxy M82
One of the maxima is interpreted to be a reflection
nebula, and the other two due to massive stars in gas
and dust poor locations in the outer disk.
They used two telescopes,
› SCAP with a diameter of 13 cm
› FOCA with a diameter of 40 cm.

M82 was observed using FOCA, which was mounted
to a balloon that rose to 40 km altitude and is
sensitive to wavelengths between 195 nm and 210
nm. They took 8 exposures of 150s each covering a
field of view of 2.3 degrees, centered on 9h 58m 57.0
s, +69 degrees 01’ 41”.





The central region was found to have a minimum
connecting the two maxima (in the form of a saddle point
in the 2D image).
The central region is therefore not a maximum of UV
emission, as expected
They conclude that the regions of high UV emission have
an absence of IR, and therefore gas and dust poor.
One possible explanation for the UV emission is the
presence of very hot burning stars in dust and gas poor
regions .
The presence of two distinct regions may either mean that
there exists two distinct emission regions or that absorbing
matter is located infront of the plane in the central regions
The telescope used to take our images
was the 40 cm Evan’s reflecting
telescope at the Glenlea Observatory in
Winnipeg Manitoba.
 An apogee AP-47 CCD camera was
used for capturing the images.
 We used ImageJ for processing our
images and developing a final
processed image of the galaxy M82







Convert the images to 32 bit.
Measure the mean value of the over scan region for
each Bias Frame image used via analyze>Set
Measurements>”check mean grey values”, then
Analyze>Measure.
This is a region of size 6 x 512 pixels along the left
hand side of each image.
Remember to open each group of images as a
Stack and to use to ROI Manager to manage each
image in the stack.
Subtract this mean pixel value from each of the bias
frames, then crop each image to 520 x 512.
The Master Bias frame is the average of 10 bias
frames, and can be created with the use of the ROI
manager and Z project

Raw Data:
› Date: Feb. 08, 2007
› Time: 7:16 – 7:18 PM
› Temperature: ›
›
›
›
›
29 °C
CloudCover: Clear
Moon: Wanning
Gibbous
Visibility: 22.7 km
Equipment: The 40
cm Evans'
reflecting
telescope
Size : 520 x 512
To Create a Master Dark, subtract the
over scan region and crop as done with
the Master Bias region. Further, subtract
the Master Bias frame from each Dark
Frame via Process>Math>Subtract.
(Remember everything must be in 32 bit
format)
 Z stack the Dark frames to create the
final Master Dark frame.


Raw Data
Date: Feb. 08, 2007
Time: 7:25 – 7:51 PM
Temperature: -29 °C
CloudCover: Clear
Moon: Waning Gibbous
Visibility: 22.7 km
Equipment: The 40 cm
Evans' reflecting
telescope
› Size : 520 x 512
› Exposure time: 300s
›
›
›
›
›
›
›
To create the Master Flat frame (in our
case Dark Sky Flats), first convert the
images to 32 bit format, subtract the over
scan region, crop to 520 x 512 pixel size,
and subtract both the Master bias frame
and Master Dark frame from each image.
 Because the stars appear in different
locations from image to image, we may
make use of the plug-in called
“Background Extractor” which will
normalize the sky frames and create the
final Master Flat image. ( Normalize each
image by Mean, and Combine stack by
Median)


Raw Data:
Date: Feb. 08-09, 2007
Time: 11:39 – 12:03 PM
Temperature: -29 °C
CloudCover: Clear
Moon: Wanning Gibbous
Visibility: 22.7 km
Equipment: The 40 cm
Evans' reflecting
telescope
› Size : 520 x 512
› Exposure time: 300 s
› Comments; The dust
halos are quite evident.
›
›
›
›
›
›
›



We must first convert the images to 32-bit
format, subtract the overscan region from
each image, crop each image to 520 x 512
pixel size, subtract the master bias frame from
each image, subtract the master dark frame
from each image, and finally divide each
image by the master flat.
Select the usable frames, and register and
combine them via the set of plug ins
“TurboReg” and “StackReg” to register and
aligned the frames,
We now have the final image of our Galaxy!

Raw data
›
›
›
›
›
›
›
›
›
Date: Feb. 08 2007
Time: 10:58 – 11:31 PM
Temperature: -29 °C
CloudCover: Clear
Moon: Wanning
Gibbous
Visibility: 22.7 km
Equipment: The 40 cm
Evans' reflecting
telescope
Size : 520 x 512
Exposure time: 300s
each


To find the field of view
for our images, we may
use an image of the
“double double” star
Eplison Lyrae.
Plotting a Profile across
both stars will lead us to
a separation in pixels
between the two stars,
and knowing the true
distance between them
can allow us to develop
a scale by which we
may calculate the
angular field of view for
our images.

We find:

Background Sky:
› Three value average:
› 1856.26, 1982.14, 1914.34
› Average : 1917.58

Faintest
observable
region of the
object
› Outer extension
›
›
›
›
›
of M82 to the left:
2467.82, 2334.34,
2300.34
Average: 2367.5
+- 80.0
Outer extension
of M82 to the
right:
2309.34, 2359.56,
2488.45
Average:
2385.79 +- 90.00

Brightest region
of the object:
the galaxies
core
› Plotting the pixel
profile of a 10
pixel radius
around the
core, we find
that its peak
pixel value is :
14479.12
For Stellar bodies, I
used the circle tool
to analyze our
image. The circle
has a radius of 8
pixels (the size of
the largest star).
 Peak pixel value of
faintest stellar
object

› The peak value for
the faintest star :
2222.737

Peak pixel
value of the
brightest
unsaturated
stellar object:
64203.707
(note : this is
now closely
approaching
the saturation
limit)
The stellar body is actually a cluster of millions of stars
associated with M82. I used the circle tool to determine the
flux through a circle of 8 pixel radius for each stellar body.
 For the brightest stellar region,

› IntDen : 5710094.058

For the faintest stellar region,
› IntDen: 403256.245

The ratio of these values is :
› 14.160
To estimate the magnitude of the faint star, we can use the
following equation:
 Where m is the magnitude of the faint star.


The faint star therefore can be estimated to have a
magnitude of m = 12.88.




Best image using
linear scaling to
easily observe faint
regions of image.
This image was
inverted via
image>look up
tables>Invert LUT
The image’s
brightness and
contrast was also
altered
The surrounding dim
stars may be more
easily seen this way.

Using :
› Image>look up
tables>royal
› Image>look up
tables >invert LUT


The following
image can be
determined.
In this image, the
brightest parts of
the core of the
galaxy may be
seen in more
detail.

Using:
› Image>look up
tables>phase

In this image, the
regions closely
surrounding the
nuclear regions
are detailed.
One can clearly
see the edges of
this region. This
image is of false
colour.
Changing the
transfer function to
a logarithmic one
will reduce
saturation as well as
increase the detail
of the brighter
regions of our
galaxy.
 The image was
obtained by
Process>Math>Log
in ImageJ

A Contour mapping
of the image will
show associations
between different
regions.
 These are the pixel
values by which the
boundaries may be
calibrated.
 We used the
following settings:





I set the outer green
boundary to a pixel value,
2300 , within error of the
values found earlier for the
outer edge of the visible
galaxy.
Orange : the boundary in
which the bright white
region which makes up the
body of the galaxy
Red: the apparent multicore nature of the galaxy
in the visible spectrum
Blue: the brightest of these
‘cores’ (the true nucleus).
Dimmest Stellar Body has a typical
Gaussian shaped distribution
curve



From this plot, the large
amount of enveloping
dust and gas around
M82’s core is most
evident. It may be
associated with the
large dips in the
luminosity distribution.
This profile plot cannot
be associated with a
Gaussian curve.
Due to perhaps the
large amount of dust
covering its center, a
large dip in the profile
may be seen.

Examining the bridge between the apparent core and
the associated bright region to the left of the nucleus,
one can more clearly see the distinction between the
two peak brightness values, and perhaps the presence of
dust and gas covering one single bright region.
Then it was scaled to ten times larger. Also, it was : image>Look up Tables>Phase. Finnaly it was
sharpened.

We may use our calculated field of view and the
boundary defined through our contour mapping to
determine the angular size of our galaxy. Measured
across and length wise:
› Its length is: 19.1 +- 0.1 cm
› Its width is: 5.5 +- 0.1 cm

The width of the whole image is: 23.4 +- 0.2 cm (error
double because measured by moving ruler once)
› The estimated angular length is : (19.1 +- 0.1 cm / 23.4 +-
0.2 cm) x = (5.66 +- 0.30 arcmins)
› The estimated angular width is : (5.4 +- 0.1 cm / 23.4 +- 0.2
cm) x = (1.60 +- 030 arcmins)


The expected angular size: 10.47’ x 4.365’
Deviation due to the definition of our galaxies outer
boundary.

Estimating our Physical size, we know:
› (Distance to object) x tan (angular size) = (physical
size of object)
Length : (11.5 +- 0.8 Mly) x tan ((5.66 +- 0.30) /
(60) deg) = 18933.93 +- 2000.00 ly
 Width: ((11.5 +- 0.8 Mly) x tan ((1.60 +- 0.30) /
(60) deg)) = 5352.34 +- 1000.00 ly

› As expected, these values are mathematically
inconsistent with the known values of :

Actual size:
(Physical Size)

This again has to do with the boundaries by
which the size of the galaxy is defined.

The spectral classification of each image
is described by the following chart:
Top Left : U
Top Right: G
Middle : R
Bottom Left: I
Bottom Right: Z


As expected, the dust and gas covering the
center of the Galaxy grows less visible as the
wavelength of light used to observe M82
increases.
Because the dust and gas absorbs the UV
radiation emitted by the hot young stars from
the Starburst regions of the galaxy, the dust is
more visible upon viewing of the galaxy at
smaller wavelengths (closer associated with
the UV spectrum ) . Remember that the dust is
represented by an absence of emission in the
UV spectrum. (dark clouds)


The galaxy I researched was M82, a prototype
Starburst Galaxy famous for heavy star formation
due to its close encounter with M81.
Through the use of several image processing
techniques including general image reduction with
the use of the
› Master Bias,
› Master Dark,
› Master Flat

And the use of several more advanced processing
techniques including
›
›
›
›

using look up tables>(invert LUT, royal, phase)
logarithmic image scaling
image sharpening
manipulation of the brightness and contrast,
Through these methods we could more easily
analyze our image.


We found that in correlation to past research in
the UV emission spectrum, the dust was more
visible (an absence of emission) as dark clouds
surrounding the center of the galaxy. Wilson
and Petipas were able to determine that the
double peaked nature could also be due to
the result of two individually separated clumps
of molecular gas collecting on a inner Lindblad
resonance (ILR) and not an edge on molecular
torus.
We determined a physical and angular size of
our galaxy, however our results were not
consistent with the expected ones
Barker S., de Grijs R, Cerviño M, 2008. Star cluster versus field star formation in the nucleus of the prototype
starburst galaxy M 82. Astrophys J 484(3): 711
Backyard Astro. 2009. Deepsky Top-100 (10): M 81 & M82. http://www.backyardastro.com/deepsky/top100/10.html
Cotton WD, Condon JJ, Arbizzani E. 1999. Arcsecond positions of UGC galaxies. Astrophys J 125:409
Courvoisier TJL, Reichen, M, Blecha, A, Golay M, Huguenin D. Far-UV imaging of the starburst galaxy M82.
Astrophys J 238(1): 63
Frommert H, Kronberg C. 1998. The Messier Catalogue. http://www.seds.org/messier/more/m082_uit.html
Marcia R. 2008. http://ircamera.as.arizona.edu/astr_250/Lectures/Lec_24sml.htm
McKeith CD, Castles J, Greve A, Downes D. 1993. Rotation of Stars and Gas in M82. Astrophys J 22 (1):98
Moor JH, Smith L, Westmoquette M, 2004. Starburst Galaxy Showers The Universe.
http://zuserver2.star.ucl.ac.uk/~msw/M82_pr/
Peach D. 2004. Binaries. http://www.damianpeach.com/binaries.htm
Petitpas GR, Wilson CD, 1999. Dynamics, Distribution, and Amount of Molecular Gas in Galaxies with NIR
Isophote Twists: NGC 2273 & NGC 5728. Cassiopeia Online September 1999 issue : 102
Petitpas GR, Wilson CD, 2000. Temperature and Density Gradients Across the Nucleus of M82. Astrophys J
538: 117
Thaller M, Doris D, Hermans-Killam L, Hurt R. 2008. Multi Wavelength Astronomy.
http://coolcosmos.ipac.caltech.edu/cosmic_classroom/multiwavelength_astronomy/multiwavelength_
museum/m82.html
The 8th European VLBI Network Symposium
on New Developments in VLBI Science and Technology
and EVN Users Meeting. 2006. www.astro.uni.torun.pl/evn2006/presentation/Tom_Muxlow.ppt
The Internet Encyclopedia of Science. 2008. Starburst Galaxy.
http://www.daviddarling.info/encyclopedia/S/starburst_galaxy.html
Wikipedia. Epsilon Lyrae. http://en.wikipedia.org/wiki/Epsilon_Lyrae
Wikpedia. Starburst Galaxy. http://en.wikipedia.org/wiki/Starburst_galaxy