Tycho Brahe’s 1572 supernova as a standard type Ia explosion revealed from its light echo spectrum
http://arxiv.org/abs/0810.5106
Type Ia supernovae (SNe Ia) are thermonuclear explosions of white dwarf stars in close binary systems. They play an important role as cosmological distance indicators and have led to the discovery of the accelerated expansion of the Universe. Among the most important unsolved questions are how the explosion actually proceeds and whether accretion occurs from a companion or via the merging of two white dwarfs. Tycho Brahe’s supernova of 1572 (SN 1572) is thought to be one of the best candidates for a SN Ia in the Milky Way. The proximity of the SN 1572 remnant has allowed detailed studies, such as the possible identification of the binary companion, and provides a unique opportunity to test theories of the explosion mechanism and the nature of the progenitor. The determination of the yet unknown exact spectroscopic type of SN 1572 is crucial to relate these results to the diverse population of SNe Ia. Here we report an optical spectrum of Tycho Brahe’s supernova near maximum brightness, obtained from a scattered-light echo more than four centuries after the direct light of the explosion swept past Earth. We find that SN 1572 belongs to the majority class of normal SNe Ia. The presence of a strong Ca II IR feature at velocities exceeding 20,000 km/s, which is similar to the previously observed polarized features in other SNe Ia, suggests asphericity in SN 1572.
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Explain this technique to me … what is the light echoing off?

dv said:

Tycho Brahe’s 1572 supernova as a standard type Ia explosion revealed from its light echo spectrum
http://arxiv.org/abs/0810.5106
Type Ia supernovae (SNe Ia) are thermonuclear explosions of white dwarf stars in close binary systems. They play an important role as cosmological distance indicators and have led to the discovery of the accelerated expansion of the Universe. Among the most important unsolved questions are how the explosion actually proceeds and whether accretion occurs from a companion or via the merging of two white dwarfs. Tycho Brahe’s supernova of 1572 (SN 1572) is thought to be one of the best candidates for a SN Ia in the Milky Way. The proximity of the SN 1572 remnant has allowed detailed studies, such as the possible identification of the binary companion, and provides a unique opportunity to test theories of the explosion mechanism and the nature of the progenitor. The determination of the yet unknown exact spectroscopic type of SN 1572 is crucial to relate these results to the diverse population of SNe Ia. Here we report an optical spectrum of Tycho Brahe’s supernova near maximum brightness, obtained from a scattered-light echo more than four centuries after the direct light of the explosion swept past Earth. We find that SN 1572 belongs to the majority class of normal SNe Ia. The presence of a strong Ca II IR feature at velocities exceeding 20,000 km/s, which is similar to the previously observed polarized features in other SNe Ia, suggests asphericity in SN 1572.
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Explain this technique to me … what is the light echoing off?

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Surely Brendon would have this answer.

interstellar dust and i presume interstellar gas clouds. at an angle to the direct light path to earth.

http://en.wikipedia.org/wiki/Light_echo

>Explain this technique to me … what is the light echoing off?

If I told you the answer, you’d know it; but by making you look it up you may learn something.

It’s echoing off all the missing ducks quacks.

interstellar dust and i presume interstellar gas clouds. at an angle to the direct light path to earth.
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I figured that was it, but that’s fucking amazing.

dv said:

interstellar dust and i presume interstellar gas clouds. at an angle to the direct light path to earth.
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I figured that was it, but that’s fucking amazing.

.

Yes, yes it is, isn’t it.

The most famous light echo is this one.

http://annesastronomynews.com/wp-content/uploads/2012/02/V838-Mon-These-images-are-showing-the-expansion-of-the-light-echo-from-May-20-2002-untill-Februari-8-2004.jpg

mollwollfumble said:

The most famous light echo is this one.

http://annesastronomynews.com/wp-content/uploads/2012/02/V838-Mon-These-images-are-showing-the-expansion-of-the-light-echo-from-May-20-2002-untill-Februari-8-2004.jpg

The second most famous light echo is extra-galactic. Hanny’s Voorwerp is the green light echo from a quasar off a cloud of intergalactic gas and dust.
http://static.vizworld.com/wp-content/uploads/2011/01/heic1102a.jpg