If we can see a brown dwarf, it's probably (1) high-parallax as seen here = close (2) also high-parallax from the star(s) = far (3) which lightsource be dim and at least the dwarf (3) young. This combination allows our non-JWST telescopes to separate its light from its star's. Like this batch.
JWST isn't the survey-'scope. It's the 'scope we point at objects we're already interested in. VHS 1256 b was one of our earlier objects-of-interest, ascertained 2016 on account it's "only" 74 light years out so with high parallax. Now the Webb is in.
The press-release claims 360 AU and 17,000 years, elliptic orbit. I assume they got that year-length from an estimation of the main stars' mass, rounding the browndwarf's mass to zero. Indeed VHS 1256 (sans dwarf) is a binary, so its mutual dance and the two bodies' parallax have been measured for some time, constraining the barycentre mass nicely. It's all much like the Centauri triplet although much much less massive - the dwarf is constrained under 20 Jupiters.
I do not find in the paper how the press-release has ascertained eccentricity - the third body has only been measured since 2016 nu? Maybe it's too near (or too far) to match the ∼8" parallax. In this case, too near, given the paper's 150 AU.
We learn that the dwarf's composition is variable. All the elements in there, it seems, churn about. In fact they might even be combining and disintegrating into new compounds as they rise and fall in the "atmosphere" - which we should probably keep calling a Convective Zone as we call such on our own Sun. Although they don't know yet if this one is still burning deuterium.
As a young browndwarf as orbits beyond the snow-line it is a proxy for the dozens of other objects like it, including the 34 new ones. Which means if we find similar convection in other dwarfs, given allowances for mass, we should be able to guess at their age. Especially if it's a steal so not part of the original.
BACKDATE 9/10 9:20 AM MST - well poop, I had to drop the 6 September poast. Ah well.
No comments:
Post a Comment