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Stellar Astrophysics: Things That Are Too Hard for Keck. Judy Cohen (Caltech)+ Evan Kirby, the 0Z team and Branimir Sesar Astronomy in the TMT Era Tokyo, Oct 2013. Four Problems. Gravitational settling in the Sun & solar modeling Extremely metal-poor stars: CNO

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stellar astrophysics things that are too hard for keck

Stellar Astrophysics: Things That Are Too Hard for Keck

Judy Cohen (Caltech)+ Evan Kirby, the 0Z team and BranimirSesar

Astronomy in the TMT Era

Tokyo, Oct 2013

four problems
Four Problems

Gravitational settling in the Sun & solar modeling

Extremely metal-poor stars: CNO

Chemical Evolution in Nearby Galaxies

The total mass of the Milky Way + finding more ultra-faint galaxies – RR Lyr + HSC/Subaru

slide5
Richard, Michaud et al predict diffusion in low Fe/H dwarfsSize of effect reduced in response to our and others early work.
slide8
M92, same for Ti12, can’t achieve needed accuracy, spent > 4 HIRES/Keck nights on MSTO. HIRES with multiplex would be great !
adding n and o
Adding N and O
  • C from 4300 strong CH band. N,O not so easy
  • N from NH band, 3360 A
  • O from OH bands, 3200 A or near 1.6 microns
  • Weak lines, in regions hard to observe
  • Really need full set of CNO abundances for best understanding
chemical evolution of the local group kirby cohen many deimos keck
Chemical Evolution of the Local Group, Kirby, Cohen + many, Deimos/Keck
  • 2850 RGB stars in 8 dSph MW satellites, most distant Leo I at 260 kpc
  • 108 stars in 7 Ultra-Faint MW satellites, most distant CVnII at 160 kpc
  • 629 in 7 Local Group isolated dIrr, most distant VV 124 at 1,400 kpc
we are now at the limit of keck
We are now at the limit of Keck
  • Can’t do ultra-faints better – very few bright giants and can’t reach more numerous MS
  • No group has had success in finding more UF, PanStars none so far, PTF not suitable for this
  • Kirby, Cohen + no more MW satellites left close enough for Deimos
rr lyr total mass of the milky way with dark matter and finding more uf mw satellites
RR Lyr: Total Mass of the Milky Way with dark matter, and finding more UF MW satellites

RR Lyrae can be found in the PTF to ~100 kpc

A period + a rough Fe/H determines an accurate luminosity and distance

We have found ~100 RR Lyr at 70 < D < 100 kpc excluding more than 100 in the known dSph, with vr can infer total mass of MW out to 100 kpc.

Using RR Lyr as lamp-posts can we find the very low luminosity stellar systems/streams in which they presumably live ?

palomar transient factory rr lyrae stars 900 rr lyr 30 r 100 kpc
Palomar Transient Factory RR LyraeStars (~900 RR Lyr 30 < R < 100 kpc)

RR Lyrae stars between 70 and 100 kpc

Se~~

how to get beyond 100 kpc hsc
How to get beyond 100 kpc – HSC !!
  • Find the RR Lyr using HSC wide survey
  • Get periods using Keck (cadence project)
  • Get vr + rough Fe/H using Keck
  • Use known RR Lyr distance + matched filter algorithm to search HSC multi-color catalog for main sequence stars in the underlying low luminosity stellar system or stream
  • HSC is the ONLY way to do this !!!