Starship Asterisk*

http://www.universetoday.com/108386/bright-new-supernova-blows-up-in-nearby-m82-the-cigar-galaxy/ wrote:
Bright New Supernova Blows Up
in Nearby M82, the Cigar Galaxy
by Bob King, Universe Today, Jan. 22, 2014

<<Wow! Now here’s a supernova bright enough for even small telescope observers to see. And it’s in a bright galaxy in Ursa Major well placed for viewing during evening hours in the northern hemisphere. Doesn’t get much better than that! The new object was discovered last night by S.J. Fossey; news of the outburst first appeared on the Central Bureau for Astronomical Telegrams “Transient Objects Confirmation Page”

Astronomers are saying this new supernova is currently at magnitude +11 to +12, so its definitely not visible with the naked eye. You’ll need a 4 inch telescope at least to be able to see it. It’s amazing it wasn’t found sooner (update — see below, as perhaps it was!). M82 is a popular target for beginning and amateur astronomers; pre-discovery observations show it had already brightened to magnitude 13.9 on the 16th, 13.3 on the 17th and 12.2 on the 19th. Cold winter weather and clouds to blame?

UPDATE: Fraser and team from the Virtual Star Party actually imaged M82 on Sunday evening, and you can see it in the video below at the 22 minute mark. It really looks like a bright spot is showing up — and that’s about a day before it was announced. Did they catch it? In the video the galaxy appears upside down as compared to the images here:

Click to play embedded YouTube video.

>>

Nitpicker wrote:
Yes, after I read the story of van Maanen linked in my last , it dawned on me that my guess was a bad one.

I shall go and sit in the corner for a few days.

http://en.wikipedia.org/wiki/John_R._Horner wrote:
<<"Jack" Horner (born June 15, 1946) is an American paleontologist who discovered and named Maiasaura, or "Good Mother Lizard", providing the first clear evidence that some dinosaurs cared for their young. He is one of the best-known paleontologists in the United States. In addition to his many paleontological discoveries, Horner served as the technical advisor for all of the Jurassic Park films, and even served as partial inspiration for one of the lead characters, Dr. Alan Grant.

Horner's 2009 book, How to Build a Dinosaur: Extinction Doesn't Have to Be Forever, describes his plan to recreate a dinosaur by genetically "nudging" the DNA of a chicken. In 2003, he discovered a fossilized tyrannosaur leg bone from which paleontologist Mary Higby Schweitzer was able to retrieve proteins in 2007. As of 2011 Horner is pursuing the project to develop the animal, which he describes as a "chickenosaurus", with a team of geneticists.>>

Nitpicker wrote:
At a guess, it is perhaps "Annual Proper Motion in arc seconds" as measured from the centre of M81, not as measured from our sky.

Nitpicker wrote:
I've never heard of Proper Motion being relative to anything other than the Solar System, but things may have been different in 1921.

http://en.wikipedia.org/wiki/Gaia_%28spacecraft%29 wrote:
<<Gaia is a space observatory to be launched by the European Space Agency (ESA) in November 2013. The mission aims to compile a 3D space catalogue of approximately 1 billion stars, or roughly 1% of stars in the Milky Way. Successor to the Hipparcos mission, it is part of ESA's Horizon 2000 Plus long-term scientific program. Gaia will monitor each of its target stars about 70 times to a magnitude 20 over a period of 5 years. Gaia will create an extremely precise three-dimensional map of stars throughout our Milky Way galaxy and beyond, determining the positions, distances, and annual proper motions of 1 billion stars with an accuracy of about 20 µas (microarcsecond) at 15 mag, and 200 µas at 20 mag.>>

neufer wrote:

[size=125][b][color=#0000FF]Plate IV in Adriaan van Maanen's 1921 paper (MA21) showing astrometrically measured internal motions for M81. '[i]The arrows indicate the mean annual motions.[/i]'[/color][/b][/size]

---

neufer wrote:

deathfleer wrote:
Am I not right if I say
that the M81 's core is spinning anti clockwise?

• You are indeed not right ...

alter-ego wrote:
<<For the most part, spiral galaxies have trailing arms. All grand design spiral arms are trailing. Statistically, the vast majority most spiral galaxies have trailing arms. The source of leading-edge arms is believed to be the result from collisions causing retrograde perturbations. It's also been observed that only parts of the galaxy may be affected, i.e outer arms may be leading while the inner arms are trailing. NGC 4622 is an example, and possibly M81.>>

I should point out that M81 is 12 Mly away such that 0.1 arcsec ~ 6 lyr.

[c]Therefore Adriaan van Maanen was "observing"
relativistic orbital proper motions ... [/c]

Nitpicker wrote:

neufer wrote:
I should point out that M81 is 12 Mly away such that 0.1 arcsec ~ 6 lyr.

Therefore Adriaan van Maanen was "observing"
relativistic orbital proper motions ...

In other words, it is only the length of the cyan-coloured arrows that is related to the cyan-coloured scale bar.
M81 itself appears much larger to us: ~800-900 arcsec across.

neufer wrote:I should point out that M81 is 12 Mly away such that 0.1 arcsec ~ 6 lyr.

Therefore Adriaan van Maanen was "observing"
relativistic orbital proper motions ...

deathfleer wrote:

alter-ego wrote:

[size=150][color=#0000FF]NGC 4622[/size][/color]

---

<<For the most part, spiral galaxies have trailing arms. All grand design spiral arms are trailing. Statistically, the vast majority most spiral galaxies have trailing arms. The source of leading-edge arms is believed to be the result from collisions causing retrograde perturbations. It's also been observed that only parts of the galaxy may be affected, i.e outer arms may be leading while the inner arms are trailing. NGC 4622 is an example.

http://articles.adsabs.harvard.edu/full ... 3.000.html

I thought it was like the water spraying out of a water sprinkler

http://en.wikipedia.org/wiki/Spiral_galaxy#Historical_theory_of_Lin_and_Shu wrote:

<<The first acceptable theory for the spiral structure was devised by C. C. Lin and Frank Shu in 1964, attempting to explain the large-scale structure of spirals in terms of a small-amplitude wave propagating with fixed angular velocity, that revolves around the galaxy at a speed different from that of the galaxy's gas and stars. They suggested that the spiral arms were manifestations of spiral density waves - they assumed that the stars travel in slightly elliptical orbits, and that the orientations of their orbits is correlated i.e. the ellipses vary in their orientation (one to another) in a smooth way with increasing distance from the galactic center. This is illustrated in the diagram. It is clear that the elliptical orbits come close together in certain areas to give the effect of arms. Stars therefore do not remain forever in the position that we now see them in, but pass through the arms as they travel in their orbits.>>

alter-ego wrote:

neufer wrote:

[size=125][b][color=#0000FF]Plate IV in Adriaan van Maanen's 1921 paper (MA21) showing astrometrically measured internal motions for M81. '[i]The arrows indicate the mean annual motions.[/i]'[/color][/b][/size]

---

deathfleer wrote:
Am I not right if I say that the M81 's core is spinning anti clockwise?

• You are indeed not right

http://messier.seds.org/m/m081.html wrote:
<<Investigations performed in 1994 have indicated that M81 has probably only little dark matter, as its rotation curve was found to fall off in the outer regions; this is in contrast to many galaxies, including our own Milky Way, for which the rotation curve increases outward. To explain the velocity of the stars in these regions, the galaxy must have a certain amount of mass. However, the total mass observed in luminous matter - stars and nebulae - is typically insufficient to explain this behaviour; thus it is assumed that there is a significant portion of mass in galaxies is non-luminous, dark matter (or at least low-luminosity matter). For M81, the percentage of dark matter is now estimated to be lower than average.>>

For the most part, spiral galaxies have trailing arms. All grand design spiral arms are trailing. Statistically, the vast majority most spiral galaxies have trailing arms. The source of leading-edge arms is believed to be the result from collisions causing retrograde perturbations. It's also been observed that only parts of the galaxy may be affected, i.e outer arms may be leading while the inner arms are trailing. NGC 4622 is an example, and possibly M81.

http://articles.adsabs.harvard.edu/full ... 3.000.html

[size=150][color=#0000FF]NGC 4622[/size][/color]

---

neufer wrote:

deathfleer wrote:
Am I not right if I say
that the M81 's core is spinning anti clockwise?

• You are indeed not right ...

alter-ego wrote:
<<For the most part, spiral galaxies have trailing arms. All grand design spiral arms are trailing. Statistically, the vast majority most spiral galaxies have trailing arms. The source of leading-edge arms is believed to be the result from collisions causing retrograde perturbations. It's also been observed that only parts of the galaxy may be affected, i.e outer arms may be leading while the inner arms are trailing. NGC 4622 is an example, and possibly M81.>>

[c]Therefore Adriaan van Maanen was "observing"
relativistic orbital proper motions ... [/c]

rstevenson wrote:

Beyond wrote:So... the milky way is rotating the opposite way of M81 Like a saw blade cutting backwards (which is used that way to cut plastics and the like).

The correct way to cut plastics, as with any other material, is to use the right kind of saw blade and run it forwards as usual.

Rob

Beyond wrote:So... the milky way is rotating the opposite way of M81 Like a saw blade cutting backwards (which is used that way to cut plastics and the like).

http://www.cfa.harvard.edu/news/2013/pr201310.html wrote:

The new results fall somewhere in between the two theories and suggest that the arms arise in the first place as a result of the influence of giant molecular clouds - star forming regions or nurseries common in galaxies. Introduced into the simulation, the clouds act as "perturbers" and are enough to not only initiate the formation of spiral arms but to sustain them indefinitely.

"We find they are forming spiral arms," explains D'Onghia. "Past theory held the arms would go away with the perturbations removed, but we see that (once formed) the arms self-perpetuate, even when the perturbations are removed. It proves that once the arms are generated through these clouds, they can exist on their own through (the influence of) gravity, even in the extreme when the perturbations are no longer there."

neufer wrote:

[size=125][b][color=#0000FF]Plate IV in Adriaan van Maanen's 1921 paper (MA21) showing astrometrically measured internal motions for M81. '[i]The arrows indicate the mean annual motions.[/i]'[/color][/b][/size]

---

deathfleer wrote:
Am I not right if I say that the M81 's core is spinning anti clockwise?

• You are indeed not right

http://messier.seds.org/m/m081.html wrote:
<<Investigations performed in 1994 have indicated that M81 has probably only little dark matter, as its rotation curve was found to fall off in the outer regions; this is in contrast to many galaxies, including our own Milky Way, for which the rotation curve increases outward. To explain the velocity of the stars in these regions, the galaxy must have a certain amount of mass. However, the total mass observed in luminous matter - stars and nebulae - is typically insufficient to explain this behaviour; thus it is assumed that there is a significant portion of mass in galaxies is non-luminous, dark matter (or at least low-luminosity matter). For M81, the percentage of dark matter is now estimated to be lower than average.>>

neufer wrote:

Beyond wrote:
The way neufer shows it, is like how a circular saw blade works.

The forward edge of the teeth rotate into what is being cut, which in this case is clockwise.

However, i don't know if all galaxy's rotate in the direction their arms point.

That's the way i sawed it.

http://www.cosmosportal.org/view/article/138223/ wrote:

---

A side-by-side comparison shows the nearby galaxy Messier 81, which is similar to our own Milky Way, in both visible (left) and ultraviolet light (right). While visible-light images of galaxies reveal the distribution of stars, ultraviolet-light images highlight the most active, young stars. The ultraviolet image of Messier 81 shows that the galaxy's spiral arms are dotted with pockets of violent star-forming activity. Note the prominent groups of young stars tracing out the spiral pattern, as well as the bulge's deficit of this population in the UV image.

The visible-light image is from the National Optical Astronomy Observatory. The ultraviolet-light image was taken by the Galaxy Evolution Explorer. (Source: NASA/JPL. Image credit: NASA/JPL-Caltech/NOAO.)>>

Beyond wrote:
The way neufer shows it, is like how a circular saw blade works.

The forward edge of the teeth rotate into what is being cut, which in this case is clockwise.

However, i don't know if all galaxy's rotate in the direction their arms point.

That's the way i sawed it.

deathfleer wrote:Beautiful photo. Am I not right if I say that the M81 's core is spinning anti clockwise?

deathfleer wrote:
Am I not right if I say that the M81 's core is spinning anti clockwise?

• You are indeed not right

http://messier.seds.org/m/m081.html wrote:
<<Investigations performed in 1994 have indicated that M81 has probably only little dark matter, as its rotation curve was found to fall off in the outer regions; this is in contrast to many galaxies, including our own Milky Way, for which the rotation curve increases outward. To explain the velocity of the stars in these regions, the galaxy must have a certain amount of mass. However, the total mass observed in luminous matter - stars and nebulae - is typically insufficient to explain this behaviour; thus it is assumed that there is a significant portion of mass in galaxies is non-luminous, dark matter (or at least low-luminosity matter). For M81, the percentage of dark matter is now estimated to be lower than average.>>