We’re back with direct imaging with Masayuki Kuzuhara.
They used the #Subaru #telescope to observe nearby accelerating stars and search for substellar companions.
They discovered 4 substellar companions, one of which is the brown dwarf HIP 21152 B. The spectrum reveals water and methane. They further modelled the orbit, giving them a dynamical mass of around 28 Mjup.#ExSSV
Their effort resulted in two more brown dwarf discoveries and one planetary!
With planet orbit modelling they determine a mass of ~13-16 Mjup (me confused? Is that still considered a planet?)
And there’s more to come! Stay tuned #ExSSV
Next up, we’ve got Thomas Vandal on #JWST #interferometry as a tool to understand #planet #formation.
Directly imaged planets - albeit few - are crucial to help us understand planet formation scenarios.
Using JWST #NIRISS #AMI aperture masking interferometry, they targeted two systems, as part of an exploratory program.
On particular finding is that the choice of reference star is important. Longer exposures are needed to study the planets (reaching contrast). #ExSSV
Another program is probing the multiplicity of 20 Y dwarfs. #AMI will not work for faint primaries, so they use a thing called #kernel #phase, using the telescope as an interferometer.
The WISE-0336 system is a Y-Y binary. For the 19 other targets they didn’t find anything, so they are looking at detection limits. #ExSSV
Next up, we’ve got Jason Wang about the #Roman #coronagraph.
Fun fact: Nancy Grace Roman envisioned imaging reflect light planets and wrote a paper about it. Jason points out how fitting it is that this will be done with Roman.
The Roman coronagraph will provide a large increase in sensitivity and demonstrate some key technologies: dark hole digging, large deformable mirrors, …#ExSSV
The coronagraph is fully assembled: to the lower left you see the filters. In-air functional testing is complete so now they need to test it in vacuum.
Roman is expected to launch towards the end of 2026/mid of 2027! #ExSSV
Next up, we’ve got Melanie Rowland on protosolar D/H abundance in the coldest brown dwarf.
In recent years, the detection of isotopologues has become a thing for exoplanets and brown dwarfs.
#Deuterium traces #planet #formation #location and #evolution. Rocky planets are thought to get their ratio from comets. Ice giants are also enhanced due to D-enriched ice, while the gas giants are not. #ExSSV
Deuterium is more detectable at colder temperatures, in particular at 4.5 micron. HDO may be observable if CH4 is absent.
They looked at WISE 0855, the coldest known brown dwarf (gas giant analogue) They detected deuterium in this object using #JWST at high significance, consistence with proto-solar.
Next up, we’ve got Melodie Kao on #magnetospheric #imaging - help 😅
All strongly magnetised planets (in the solar system) have radiation belts: interestingly this alters biochemistry.
We’ve never directly characterised magnetospheres of planets outside the solar system, but auroras on brown dwarfs!
So they wanted to resolve this spatially: and they did! They think this is the first “Jupiter radiation analogue” outside the solar system #ExSSV
So what’s the source? It’s not stellar because this friend is lonely in space.
Jupiter serves as inspiration: Io ploughs through the plasma around (?) Jupiter. Could this be happening in brown dwarfs?
Maybe brown dwarf binaries can explain it? Nope maybe not because binarity enhances radiation belt occurrence.
The jury is still out on what’s happening! #ExSSV
Last for this session, we’ve got Brendan Bowler on spin-orbit angles beyond 10 AU for directly imaged planets and brown dwarfs.
Reasons for misalignment in the solar system may be primordial or post formation interactions, even stellar winds or planet nine.
Inclination differences of directly imaged planets provide clues about the true obliquity… I got a bit lost there, it seems to be hard to get the alignment completely because of some degeneracies. #ExSSV
For a sample of 21 systems, there is enough info to look at the inclination: 11/21 are confidently or likely misaligned.
What can we learn bout the underlying obliquity distribution: isotropic? Perfect aligned? Mixture?
The mixture case seems to be favoured for now.
The big picture? Hot Jupiters are misaligned around hot stars, warm Jupiters are aligned around cool stars, directly imaged planets are aligned around hot stars.
Bibiana Prinoth (moved!)
jacob ö+