Starship Asterisk*

http://apod.nasa.gov/apod/ap080704.html

Well, this is a beauty isn't it. Looks like a cheerleader's pom-pom.
Save the cheerleader....
Can anybody identify the white/yellow line that runs along the outer edge of this 'bubble' at top right?
Is it just a thickening of matter that is highlighted, or something else?

Andy Wade wrote:http://antwrp.gsfc.nasa.gov/apod/ap080704.html

Well, this is a beauty isn't it. Looks like a cheerleader's pom-pom.
Save the cheerleader....
Can anybody identify the white/yellow line that runs along the outer edge of this 'bubble' at top right?
Is it just a thickening of matter that is highlighted, or something else?

All it said was " optical data in yellowish hues". I'm not sure what that means. I do however believe that this makes a nice star burst for the Fourth of July which we celebrate in the US. 8)

Have a nice day.

Orin

1006? What a year to waste a supernova on a bunch of Medieval humans. Why not a spectacular supernova in my lifetime? Visible in the daytime, long-lasting, the whole show. I've seen enough disappointing comets with a few good ones thrown in, even an awesome solar eclipse or two, but I want something more entertaining than fireworks just once. Where do I file my request? Of course, due to the sluggish speed of light, it should have happened already (unless it's really close - unlikely) if I'm going to see it. What sense does it make to wish for a past event?

APOD wrote:Credit: X-ray - NASA/CXC/Rutgers/G.Cassam-Chenai, J.Hughes et al.; Radio - NRAO/AUI/NSF/GBT/VLA/
Dyer, Maddalena & Cornwell; Optical - Middlebury College/F.Winkler, NOAO/AURA/NSF/CTIO Schmidt & DSS

Can I buy another vowel? Seriously, three teams for one composite is impressive. I wonder if the data gathering was coordinated or if putting it together was an afterthought.

And here's what I've learned today from reading the caption, its links, and its grandlinks: When wondering about the origins of cosmic rays, I should not have been envisioning particles being shot out of a thermonuclear process at full speed; I should have envisioned particles being accelerated to speed by other phenomena.

And here's what I think about when I look at the outer shell of the supernova remnant: It took 1000 years to attain a radius of 30 light years. That's a debris speed of .03 times the speed of light - a pretty fast speed to which to accelerate the entire mass of a star, but not fast enough if you look at the shell as the range of a space traveler from a star at the center.

Andy Wade wrote:Save the cheerleader

Save the world.

And reduce light pollution.

orin stepanek wrote:

Andy Wade wrote:http://antwrp.gsfc.nasa.gov/apod/ap080704.html

Well, this is a beauty isn't it. Looks like a cheerleader's pom-pom.
Save the cheerleader....
Can anybody identify the white/yellow line that runs along the outer edge of this 'bubble' at top right?
Is it just a thickening of matter that is highlighted, or something else?

All it said was " optical data in yellowish hues". I'm not sure what that means. I do however believe that this makes a nice star burst for the Fourth of July which we celebrate in the US. 8)

Have a nice day.

Orin

I believe the ribbon of bright emission at the upper-right is where the front of the expanding supernova shell is beginning to impact a relatively dense region of interstellar material.

http://heritage.stsci.edu/2008/22/caption.html

Hello All,

There are two of what look like strong radio sources, one at 9:00 and, to the right of center, at about 4:00. They appear to be in the background and this (wull, yaahh) brings up a question.

Since this "pom-pom" is the remnant of SN1006 then the relatively new kid on the block is a kind of overlay, if you will, in front of the existing objects behind it. So would the two radio emission sources mentioned have their radio waves somehow altered by passing through 1006 on the way to Earth?

orin stepanek wrote:

Andy Wade wrote: http://antwrp.gsfc.nasa.gov/apod/ap080704.html
Can anybody identify the white/yellow line that runs along the outer edge of this 'bubble' at top right?
Is it just a thickening of matter that is highlighted, or something else?

All it said was " optical data in yellowish hues"

<<Using bits and pieces of historical accounts, Palomar astronomer Walter Baade searched for a possible remnant using the 48” Schmidt reflector near the Star Beta Lupi without success. It wasn’t until 1965 that a 30' circular radio shell was found by F. Gardner and D. Milne. Winkler and Laird confirmed this location as an X-ray source in 1976. Up until this time, no optical confirmation of any type of remnant was found. Such was also been the case of Tycho’s supernova and Kepler’s Supernova, where only radio emission has been observed. In 1976, Canadian astronomer Sidney van den Bergh discovered a faint optical filament on the northwest portion of the radio remnant. He used the 4-meter telescope at the Cerro Tololo Observatory in Chile. The filament was thin and thickness varied from 1'' to 9'' across a 10' long strip. No other optical remnants have been found, except in this northwest area of the remnant.>>
http://www.weblore.com/richard/1006_supernove.htm

G'day astrolabe,

you wrote:There are two of what look like strong radio sources, one at 9:00 and, to the right of center, at about 4:00. They appear to be in the background and this (wull, yaahh) brings up a question.

Definitely background. The red structure Andy Wade called a pompom, is merely the result of synchrotron radiation, which is a telltale sign (fingerprint) of synchrotron radiation. The flux of the source obeys nearly the inverse square root law (0.54 in stead of 0.5). The difference Berezhko et al (http://www.aanda.org/index.php?option=a ... right.html) contribute to influence of the shock front. Next to synchrotron radiation, bremstrahlung (derived from the German words Bremse and Strahlung, which mean brake and radiation), is detected. Bremstrahlung originates when charged matter is decellerated. Regarding the origin of the SN 1006 remnant, a radial structure is expeceted. In these locations where the expanding matter (about 1 solar mass was ejected) of the SN 1006 hits the interstellar medium, electrons are decellerated, and as Maxwell states, accellerations of charged material creates radiation. The difference between the distribution of both types of radiation is visualy explained in a pdf document of ESA (http://integral.esa.int/workshops/Jan20 ... sn1006.pdf). See sheet 3.

The article of Berezhko et al is worth reading, although it might be a little difficult for non professional astronomers (like me).

Hi Everybody,

Thanks for the helpful replies to my original question, it is much appreciated.
I notice that the debris cloud limb looks flattened/oblate at the point of the brightened yellow/white line and wondered if this is because the matter which is causing the brightness in the limb is also slowing the shock front down a little, resulting in the flattened edge at this point?

Andy Wade wrote:I notice that the debris cloud limb looks flattened/oblate at the point of the brightened yellow/white line and wondered if this is because the matter which is causing the brightness in the limb is also slowing the shock front down a little, resulting in the flattened edge at this point?

Right! A simple experiment. Go to a pond and throw two pebbles into the water, separated over a few meters. The wave fronts will interact. The resulting wave just between the two centers of the circular waves, is flattened. This is of course a 2D analogon. If you do not have a pond, use a bathtub, filled with water. Not too much water, to prevent a fight with your wive/friend or neighbours below.

As an explanation for the flattened yellow line i was thinking of a local densification of the interstellar medium. For an experiment on that situation, we need water, oil, maple sirup, molten chocolat etc, it gets a little too messy to perform such experiments.

Hello Henk21cm,

Thanks a mil for an amazing reply! I honestly don't know how you folks do it but, like Andy Wade, I have truly enjoyed being the beneficiary. Like starnut said, stick around long enough and the answers, where there can be answers, will come, or something to that effect.

Now, I've only asked this next question of one other person in this Forum but, after reading your reply, and more than a few others authored by you I need to ask you this as well: Just who are you really, and what have you done with Henk21cm?

H ubble has a nice image of the string
http://hubblesite.org/newscenter/archiv ... 2/image/a/

Made the High Energy Astrophysics Picture of the Week (HEAPOW)
HEAPOW: Once a Star (2008 July 07)
Chandra: SN 1006: Liberating Star Stuff

Andy Wade wrote:Save the cheerleader....

Can't wait for Heroes to come back. Villains 09/22
http://www.nbc.com/Heroes/nexton/

http://chandra.harvard.edu/chronicle/04 ... index.html

<<The brightest supernova observed was the supernova of 1006 AD, which was brighter than Venus and visible for several years. However, the remnant of SN 1006 has not attracted nearly as much attention as the supernova of 1054 AD, which produced the Crab Nebula. This is because SN 1006 was likely produced by a thermonuclear explosion that completely disintegrated a white dwarf star (a Type Ia explosion), leaving nothing behind except the expanding stellar debris. In contrast, the Crab Nebula was the product of the collapse of the core of a massive star. The collapse triggered a Type II supernova that ejected most of the star, but left behind a rapidly spinning neutron star. This cosmic dynamo produces a tornado of magnetic fields and high-energy particles that continue to light up the expanding debris.>>
---------------------------------------------------
SN 1006 : 10 times brighter than Venus - visible for 3 years

SN 1054 (Crab) : bright as Venus - visible for 21 months
SN 1572 (Tycho) : bright as Venus - visible for 18 months

SN 1604 (Kepler) : brighter than Jupiter - visible for 12 months
---------------------------------------------------
http://en.wikipedia.org/wiki/Supernova
http://en.wikipedia.org/wiki/Type_Ia_supernova
Type Ia supernova [e.g., SN 1006]

<<There are several means by which a supernova of this type can form, but they share a common underlying mechanism. If a carbon-oxygen white dwarf accreted enough matter to reach the Chandrasekhar limit of about 1.38 solar masses (for a non-rotating star), it would no longer be able to support the bulk of its plasma through electron degeneracy pressure and would begin to collapse. However, the current view is that this limit is not normally attained; increasing temperature and density inside the core ignite carbon fusion as the star approaches the limit (to within about 1%), before collapse is initiated. Within a few seconds, a substantial fraction of the matter in the white dwarf undergoes nuclear fusion, releasing enough energy (1–2 × 1044 joules) to unbind the star in a supernova explosion. An outwardly expanding shock wave is generated, with matter reaching velocities on the order of 5,000–20,000 km/s, or roughly 3% of the speed of light. There is also a significant increase in luminosity, reaching an absolute magnitude of -19.3 (or 5 billion times brighter than the Sun), with little variation.

One model for the formation of this category of supernova is a close binary star system. The larger of the two stars is the first to evolve off the main sequence, and it expands to form a red giant. The two stars now share a common envelope, causing their mutual orbit to shrink. The giant star then sheds most of its envelope, losing mass until it can no longer continue nuclear fusion. At this point it becomes a white dwarf star, composed primarily of carbon and oxygen. Eventually the secondary star also evolves off the main sequence to form a red giant. Matter from the giant is accreted by the white dwarf, causing the latter to increase in mass.

Another model for the formation of a Type Ia explosion involves the merger of two white dwarf stars, with the combined mass momentarily exceeding the Chandrasekhar limit. A white dwarf could also accrete matter from other types of companions, including a main sequence star (if the orbit is sufficiently close).

Type Ia supernovae follow a characteristic light curve—the graph of luminosity as a function of time—after the explosion. This luminosity is generated by the radioactive decay of nickel-56 through cobalt-56 to iron-56. The peak luminosity of the light curve was believed to be consistent across Type Ia supernovae (the vast majority of which are initiated with a uniform mass via the accretion mechanism), allowing them to be used as a secondary standard candle to measure the distance to their host galaxies. However, recent discoveries reveal that there is some evolution in the average lightcurve width, and thus in the intrinsic luminosity of Supernovae, although significant evolution is found only over a large redshift baseline.>>

Qev wrote:

orin stepanek wrote:

Andy Wade wrote:http://antwrp.gsfc.nasa.gov/apod/ap080704.html
Can anybody identify the white/yellow line that runs along the outer edge of this 'bubble' at top right? Is it just a thickening of matter that is highlighted, or something else?

All it said was " optical data in yellowish hues". I'm not sure what that means.

I believe the ribbon of bright emission at the upper-right is where the front of the expanding supernova shell
is beginning to impact a relatively dense region of interstellar material.
http://heritage.stsci.edu/2008/22/caption.html

I don't know anything about large hypothetical "relatively dense regions of interstellar material"
but two things we certainly can surmise about about an expanding Ia supernova explosion:

• 1) It will quickly impact a large companion giant star that is blocking almost one entire hemisphere
  
  2) and it will first impact the much less significant mass that makes up it's own accretion disk.

What if:

• 1) That large companion giant star is rapidly transformed into a "giant yellow smoke ring"
  (Tycho’s supernova's "giant smoke ring" appears to be blown almost directly away from us.).
  
  2) The thin remnant accretion disk somehow defines the blue X-ray band separating the two red radio lobes.

http://antwrp.gsfc.nasa.gov/apod/ap080704.html

neufer wrote: I don't know anything about large hypothetical "relatively dense regions of interstellar material"
but two things we certainly can surmise about about an expanding Ia supernova explosion:

• 1) It will quickly impact a large companion giant star that is blocking almost one entire hemisphere
  
  2) and it will first impact the much less significant mass that makes up it's own accretion disk.

What if:

• 1) That large companion giant star is rapidly transformed into a "giant yellow smoke ring"
  (Tycho’s supernova's "giant smoke ring" appears to be blown almost directly away from us.).
  
  2) The thin remnant accretion disk somehow defines the blue X-ray band separating the two red radio lobes.

http://antwrp.gsfc.nasa.gov/apod/ap080704.html

If the Type 1a supernova explosion results in a complete disintegration of the white dwarf and the blast wave impacts the close companion star, possibly blowing away the companion's outer layer, wouldn't the companion's core be still intact since it would be too dense to be destroyed by the blast? If so, wouldn't the companion's core still be detectable but moving away at a high speed from the center of the system due to the slingshot effect?

Gary

starnut wrote:

neufer wrote: I don't know anything about large hypothetical "relatively dense regions of interstellar material"
but two things we certainly can surmise about about an expanding Ia supernova explosion:

• 1) It will quickly impact a large companion giant star that is blocking almost one entire hemisphere
  
  2) and it will first impact the much less significant mass that makes up it's own accretion disk.

What if:

• 1) That large companion giant star is rapidly transformed into a "giant yellow smoke ring"
  (Tycho’s supernova's "giant smoke ring" appears to be blown almost directly away from us.).
  
  2) The thin remnant accretion disk somehow defines the blue X-ray band separating the two red radio lobes.

http://antwrp.gsfc.nasa.gov/apod/ap080704.html

If the Type 1a supernova explosion results in a complete disintegration of the white dwarf and the blast wave impacts the close companion star, possibly blowing away the companion's outer layer, wouldn't the companion's core be still intact since it would be too dense to be destroyed by the blast? If so, wouldn't the companion's core still be detectable but moving away at a high speed from the center of the system due to the slingshot effect?

Certainly not as high a speed ejection as the lighter outer layers.

There may well be nothing left but an insignificant (and hard to find) brown dwarf
(; perhaps the Spitzer IR telescope could be used to look for such things).

apodman wrote:Where do I file my request? Of course, due to the sluggish speed of light, it should have happened already (unless it's really close - unlikely) if I'm going to see it. What sense does it make to wish for a past event?

I keep saying Betelgeuse three times, but so far, nothing.

-Noel

NoelC wrote:I keep saying Betelgeuse three times, but so far, nothing.

Maybe you ought to try adding Eta Carinae.

neufer wrote: I don't know anything about large hypothetical "relatively dense regions of interstellar material"
but two things we certainly can surmise about about an expanding Ia supernova explosion:

• 1) It will quickly impact a large companion giant star that is blocking almost one entire hemisphere
  
  2) and it will first impact the much less significant mass that makes up it's own accretion disk.

Gary and Art, your remark triggered a thought. Initially there is the blast of the expoding star. The companion shields partly the blast. Art mentioned that the shielded area of the hemisphere could be as much as half the visible hemisphere. The blast encounters the companion and blows part of her atmosphere away. If the blast could have been treated as a wave, like in a pond, and if some structure was blocking the wave, it would bend around the object. In a matter of speach, the blast bends similarly around the companion. Alternatively the atmosphere at either side of the core of the companion can be conceived as two independent sources for a secundary blast.

Since the original blast has encountered the relative dense atmosphere of the companion, part of the kinetic energy of the blast is transfered to the companions atmosphere, which is at rest. As a result two things will happen:

1. The original blast looses some energy and thus velocity and travels somewhat slower than in the area where the blast never encountered an companion
2. Part of the atmosphere of the companion is blown away and becomes part of the explosion

This thought, highly speculative however, leads to three predictions:

1. The nebula has lost its radial symmetry. As seen from the earth it has a vertical mirror symmetry.
2. The original visual angle of the companion must be roughly conserved.
3. The shock front in the shielded area must have traveled less far than in the unshielded area. A circular pattern will have a dent

I took the liberty to do some image processing on the original image. First of all i digitally removed all stars, using the green image. Then i determined the original circular pattern, if there would not have been a companion, blocking the blast pattern of the exploding star. Then i determined the mirror axis, indicated by a dashed line, with V. Finally i guessed an area, in which the filament is visible. This is indicated with the two short lines at either side of the V line. Although i used a linear structure element for the removal of stars, in order to keep the filament, the filament is partly damaged in the operation. The green colour plane is not shown here. The filament is particularly clear in the red and green colour planes. In the blue colour plane the filament is more blurred and somewhat behind the filament in the red and green colour plane.

Another interesting point is the location of the radio lobes, relative to the mirror lne, like two ears, visible in the red colour plane. Such lobes are the fingerprint of Bremstrahlung.
The difference in distance relative to the center of the nebula and the edge, for the shielded and unshielded area is particularly pronounced in the blue colour plane. (Blue is most dented).

Interesting analysis, Henk. I was wondering if you recreated the RGB from the composite picture, or did you use the originals (see http://chandra.harvard.edu/photo/2008/sn1006c/more.html). This isn't a visible light picture (at least not completely). The blue is xray, red radio, and yellow (not green) is the visible spectrum. Does this change your analysis? Could the filament be evidence of the atmosphere of the companion star?

bystander wrote:Interesting analysis, Henk. I was wondering if you recreated the RGB from the composite picture, or did you use the originals (see http://chandra.harvard.edu/photo/2008/sn1006c/more.html).

Unfortunatedly the first: i used the larger image under the APOD, which is a combined image. The images at Chandra's site are better for the analysis. Saterday i'll try again with the easier Chandra images.

bystander wrote:and yellow (not green) is the visible spectrum. Does this change your analysis?

Considerably. In an RGB image a yellow line is a combination of a red and green line. So if you mention yellow, it explains why the filament is visible in the green and red colour plane, whereas in the blue it is hardly or not visible. (recognizing colours is not my best asset). Furthermore, since no stars have to be removed, and since the red and green image lack stars, it is much easier to determine the symmetry of the nebula: artefacts introduiced by the removal of the stars are missing. Additionally the images are available as TIFF, which is a lossless format, without the nasty DCT artefacts of a JPG image. Working with TIFF is like sitting in a smooth velvet couch, in stead of on a granite JPG chair. Your hint to Chandra is much appreciated.

bystander wrote:Could the filament be evidence of the atmosphere of the companion star?

I do not know. For me it is rather hard to understand why the blown away atmosphere did not disperse, since the he pressure of the atmosphere is considerably higher than the surrounding interstellar space.
Furthermore it would be a sheer coincidence that the axis through the centers of the two stars is exactly perpendicular to the direction between the stars and our sun.

henk21cm wrote:Your hint to Chandra is much appreciated.

Glad I could cause you more work!

The Chandra page said the stars were added from AAO2. You might be able to use the same data to get rid of them.
http://archive.stsci.edu/cgi-bin/dss_form

Also, there is a two color xray image on the Chandra page that might provide more insight to the xray data.

bystander wrote: Glad I could cause you more work!

Well, that does not matter, its hobby, the last A in JAA (just an amateur). As the subject reads, i have a legal question and i'm not very good in legal questions. I would appreciate some help. On http://chandra.harvard.edu/photo/image_use.html it is reported:

<<Quote: To request permission to use Chandra images, video or other media, please use our Permission Request Form. :etouQ>>

When i open the form, http://chandra.harvard.edu/edu/request_perm.html it reads:

<<Quote: The images on this web site may be used for non-commercial educational and public information purposes. Please credit images to "NASA/CXC/SAO" unless other credits are given. In that case, credit the appropriate organization(s) or person(s) as they are listed with the image on our site.

If you have further questions, or a special condition, please submit the following: (request form). :etouQ>>

On the first page it says: fill in the form, on the second page: only if you have special requests, which i do not have. Filling in a form when it is not necessary, causes Chandra extra work, nobody needs. Not filling in the form makes me a freeloader.

Like King Crimson: "Confusion is in my mind".

IANAL, but here's how I see it:

a. Non-commercial educational and public information purposes. --> Permission granted to use the images, but give credit.

b. All other purposes --> Fill in the form to ask for permission and conditions before using the images.

And I would put you and this forum in the (a) category.