ESO: SN 1987A: Seeing a Stellar Explosion in 3D

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ESO: SN 1987A: Seeing a Stellar Explosion in 3D

Post by bystander » Wed Aug 04, 2010 1:40 pm

Seeing a Stellar Explosion in 3D
European Southern Observatory | eso1032 | 04 Aug 2010
Astronomers using ESO’s Very Large Telescope have for the first time obtained a three-dimensional view of the distribution of the innermost material expelled by a recently exploded star. The original blast was not only powerful, according to the new results. It was also more concentrated in one particular direction. This is a strong indication that the supernova must have been very turbulent, supporting the most recent computer models.

Unlike the Sun, which will die rather quietly, massive stars arriving at the end of their brief life explode as supernovae, hurling out a vast quantity of material. In this class, Supernova 1987A (SN 1987A) in the rather nearby Large Magellanic Cloud occupies a very special place. Seen in 1987, it was the first naked-eye supernova to be observed for 383 years (eso8704), and because of its relative closeness, it has made it possible for astronomers to study the explosion of a massive star and its aftermath in more detail than ever before. It is thus no surprise that few events in modern astronomy have been met with such an enthusiastic response by scientists.

SN 1987A has been a bonanza for astrophysicists (eso8711 and eso0708). It provided several notable observational ‘firsts’, like the detection of neutrinos from the collapsing inner stellar core triggering the explosion, the localisation on archival photographic plates of the star before it exploded, the signs of an asymmetric explosion, the direct observation of the radioactive elements produced during the blast, observation of the formation of dust in the supernova, as well as the detection of circumstellar and interstellar material (eso0708).

New observations making use of a unique instrument, SINFONI, on ESO’s Very Large Telescope (VLT) have provided even deeper knowledge of this amazing event, as astronomers have now been able to obtain the first-ever 3D reconstruction of the central parts of the exploding material.

This view shows that the explosion was stronger and faster in some directions than others, leading to an irregular shape with some parts stretching out further into space.
The 3-D Structure of SN 1987A’s Inner Ejecta - K Kjær et al

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Re: ESO: SN 1987A: Seeing a Stellar Explosion in 3D

Post by Beyond » Wed Aug 04, 2010 3:57 pm

Does anyone list how many light years long this amazingly looking object is?
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Re: ESO: SN 1987A: Seeing a Stellar Explosion in 3D

Post by neufer » Wed Aug 04, 2010 4:40 pm

beyond wrote:Does anyone list how many light years long this amazingly looking object is?
The inner ring is ~0.66 lyrs in radius

0.66 lyrs ~ 168,000 lyrs x tan(0.808 arcseconds)
http://en.wikipedia.org/wiki/SN_1987A wrote:
<<The three bright rings around SN 1987A are material from the stellar wind of the progenitor. These rings were ionized by the ultraviolet flash from the supernova explosion, and consequently began emitting in various emission lines. These rings did not "turn on" until several months after the supernova, and the turn-on process can be very accurately studied through spectroscopy. The rings are large enough for their angular size to be measured accurately: the inner ring is 0.808 arcseconds in radius. Using the distance light must have traveled to light up the inner ring as the base of a right angle triangle, and the angular size as seen from the Earth for the local angle, one can use basic trigonometry to calculate the distance to SN1987A, which is about 168,000 light-years>>
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Re: ESO: SN 1987A: Seeing a Stellar Explosion in 3D

Post by Beyond » Wed Aug 04, 2010 5:00 pm

neufer wrote:
beyond wrote:Does anyone list how many light years long this amazingly looking object is?
The inner ring is ~0.66 lyrs in radius

0.66 lyrs ~ 168,000 lyrs x tan(0.808 arcseconds)
http://en.wikipedia.org/wiki/SN_1987A wrote:
<<The three bright rings around SN 1987A are material from the stellar wind of the progenitor. These rings were ionized by the ultraviolet flash from the supernova explosion, and consequently began emitting in various emission lines. These rings did not "turn on" until several months after the supernova, and the turn-on process can be very accurately studied through spectroscopy. The rings are large enough for their angular size to be measured accurately: the inner ring is 0.808 arcseconds in radius. Using the distance light must have traveled to light up the inner ring as the base of a right angle triangle, and the angular size as seen from the Earth for the local angle, one can use basic trigonometry to calculate the distance to SN1987A, which is about 168,000 light-years>>
AH - So the .66lyrs on my moniter is 1/4 inch. The object is 3 1/4 inches long. 13 x .66 = 8.58lyrs. The object is 8.58 lyrs long.
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Re: ESO: SN 1987A: Seeing a Stellar Explosion in 3D

Post by bystander » Wed Aug 04, 2010 6:49 pm

The object on your monitor is an artist's impression.

From a 2007 STScI article:
  • A dumbbell-shaped central structure that has now grown to one-tenth of a light-year long. The structure consists of two blobs of debris in the center of the supernova racing away from each other at roughly 20 million miles an hour.

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Re: ESO: SN 1987A: Seeing a Stellar Explosion in 3D

Post by neufer » Wed Aug 04, 2010 7:27 pm

bystander wrote:From a 2007 STScI article:
  • A dumbbell-shaped central structure that has now grown to one-tenth of a light-year long.

    The structure consists of two blobs of debris in the center of the supernova
    racing away from each other at roughly 20 million miles an hour.
Those blobs are the dolphin and the anti-dolphin!
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Re: ESO: SN 1987A: Seeing a Stellar Explosion in 3D

Post by Ann » Wed Aug 04, 2010 7:41 pm

Using the distance light must have traveled to light up the inner ring as the base of a right angle triangle, and the angular size as seen from the Earth for the local angle, one can use basic trigonometry to calculate the distance to SN1987A, which is about 168,000 light-years
That's great! Then we have a very good measurement of the distance to the Large Magellanic Cloud, don't we?

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Re: ESO: SN 1987A: Seeing a Stellar Explosion in 3D

Post by bystander » Wed Aug 04, 2010 8:06 pm

neufer wrote:Those blobs are the dolphin and the anti-dolphin!
Those are mighty fast dolphins!

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Re: ESO: SN 1987A: Seeing a Stellar Explosion in 3D

Post by neufer » Wed Aug 04, 2010 8:12 pm

Ann wrote:
Using the distance light must have traveled to light up the inner ring as the base of a right angle triangle, and the angular size as seen from the Earth for the local angle, one can use basic trigonometry to calculate the distance to SN1987A, which is about 168,000 light-years
That's great! Then we have a very good measurement of the distance to the Large Magellanic Cloud, don't we?
A reasonably good independent measurement of the distance to the LMC.
http://en.wikipedia.org/wiki/Large_Magellanic_Cloud wrote:
<<Determining a precise distance to the LMC, as with any other galaxy, was challenging due to the use of standard candles for calculating distances, with the primary problem being that many of the standard candles are not as 'standard' as one would like; in many cases, the age and/or metallicity of the standard candle plays a role in determining the intrinsic luminosity of the object. The distance to the LMC has been calculated using a variety of standard candles, with Cepheid variables being one of the most popular. Cepheids have been shown to have a relationship between their absolute luminosity and the period over which their brightness varies. However, Cepheids appear to suffer from a metallicity effect, where Cepheids of different metallicities have different period-luminosity relations. Unfortunately, the Cepheids in the Milky Way typically used to calibrate the period-luminosity relation are more metal rich than those found in the LMC. Recently, the Cepheid absolute luminosity has been re-calibrated using Cepheid variables in the galaxy NGC 4258 that cover a range of metallicities. Using this improved calibration, they find an absolute distance modulus of (m − M)0 = 18.41, or 48 kpc (~157,000 light years). This distance, which is slightly shorter than the typically assumed distance of 50 kpc, has been confirmed by other authors.

In the era of 8-meter-class telescopes, eclipsing binaries have been found throughout the Local Group. Parameters of these systems can be measured without mass or compositional assumptions. The light echoes of supernova 1987A are also geometric measurements, without any stellar models or assumptions. By cross-correlating different measurement methods, one can bound the distance; the residual errors are now less than the estimated size parameters of the LMC. Further work involves measuring the position of a target star or star system within the galaxy (i.e., toward or away from the observer).>>
Art Neuendorffer

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So long and thanks for all the fission

Post by neufer » Wed Aug 04, 2010 8:22 pm

bystander wrote:
neufer wrote:Those blobs are the dolphin and the anti-dolphin!
Those are mighty fast dolphins!
The dolphins, aware of the destruction of Sanduleak -69° 202a by the Vogons, left Sanduleak -69° 202a for an alternate dimension but not before replacing the destroyed Sanduleak -69° 202a with a new version and transporting EVERyone and EVERything to it.
Art Neuendorffer

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