Could there have been some mass transfer between the then Red giant Pup and Sirius A back when the originally B4 star was evolving towards white dwarf-dom?

As I’ve already mentioned, at the end of the second paragraph of my post (#31) above, Sirius B — while it passed through the red giant stage — may have enriched the metallicity of its companion.

Could this have effected the “Dogstar” (Sirius A) and could we learn anything of that somehow?

According to the Wikipedia (Sirius) article, the spectrum of Sirius A shows deep metallic lines, indicating an enhancement in elements heavier than helium, such as iron — 316% greater proportion of iron to hydrogen in its atmosphere than that in the Sun’s atmosphere.

Also surprised to hear this as I too thought accretion was the main cause for type Ia Supernovae & not merger.

@ 31. IVAN3MAN AT LARGE :

Could there have been some mass transfer between the then Red giant Pup and Sirius A back when the originally B4 ( ) star was evolving towards white dwarf-dom? Could this have effected the “Dogstar” (Sirius A) and could we learn anything of that somehow? Does anyone know?

Also the “Little Dogstar” Procyon is coincidentally quite a similiar system & situation only with stars that are lower in spectral type (F5 V-IV & white dwarf) & thus slightly dimmer and slightly further away. (11 ly vs 9.) The two Procyonese stars are closer together (15 AU vs 19 AU) and thus harder to split too. See Kaler’s Stars site’s Procyon page :

http://stars.astro.illinois.edu/sow/procyon.html

Wonder if this finding means that these two (very remotely concievably) potentially dangerous supernova candidates

HR 8210 : http://jumk.de/astronomie/special-stars/hr-8210.shtml

& T Pyxidis : http://blogs.discovermagazine.com/badastronomy/2010/01/07/no-a-nearby-supernova-wont-wipe-us-out/

are safer & less dangerous than thought then?

Reviewing the (brief) answer I gave in my post above, I now realize that I should have been more specific, but I was in a rush. I had based my answer on the Sirius binary system, in which the two stars orbit around their common centre of gravity at a distance of about 20 astronomical units (approximately the distance between the Sun and Uranus) from each other over a period of 49.9 years. Sirius A, the brighter component, is a main sequence star of spectral type A1V, with a mass of about 2.1 times that of the Sun; whereas Sirius B, a white dwarf, is 0.98 solar masses, which is nearly double the average of 0.5 to 0.6 solar masses for white dwarfs, but packs that mass into a volume approximately the size of the Earth!

The age of the Sirius binary system has been estimated at around 230 million years. Since a white dwarf only forms after the star has evolved from the main sequence and then passed through a red giant stage, it is estimated that when Sirius B was less than half its current age, approximately 120 million years ago, the original star had a mass of about 5 solar masses and was a type B4-5 star when it still was on the main sequence before eventually shedding most of its mass after passing through the red giant stage; it may also have enriched the metallicity of its companion as a result.

It is predicted that Sirius A will have completely exhausted the store of hydrogen at its core within a billion years of its formation. At this point, it will also pass through a red giant stage, then eventually shed its outer layers and settle down to become a white dwarf; however, I do not think that this binary star pair are close enough for mass transfer to occur resulting in a nova or Type Ia supernova. (Just as well; otherwise, it might be curtains for all of us!)