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IPERCOOL What we have vs what we need - spectroscopy

IPERCOOL What we have vs what we need - spectroscopy. David Pinfield University of Hertfordshire 10th Dec 2010. Contents Why is spectroscopy so important? Facilities – what do we have? Objects – what do we need? Discussion & follow-on actions. Why is spectroscopy so important?.

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IPERCOOL What we have vs what we need - spectroscopy

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  1. IPERCOOLWhat we have vs what we need - spectroscopy David Pinfield University of Hertfordshire 10th Dec 2010 Contents Why is spectroscopy so important? Facilities – what do we have? Objects – what do we need? Discussion & follow-on actions

  2. Whyisspectroscopyso important? • Spectral types • Dictated by the presence and strength of the main absorbers • Basic level – tells us about Teff • Allow us to estimate spectroscopic distances • New important absorber = New spectral class • Histograms constrain the IMF and sub-stellar birth-rate

  3. Whyisspectroscopyso important? • Spectral type at different wavelengths • “Peculiar” objects – changing types at different wavelengths • Unresolved binarity? • Gravity and metallicity outliers? • Non typical abundances? • Activity? • Rapid rotation?

  4. Whyisspectroscopyso important? • Measuring bolometric flux • Need broad wavelength coverage (+mid IR) • Combined with parallax -> Luminosity • If theoretical radii are reliable, can get reliable Teffs • Keep monitoring results from transit surveys to check if radii are OK (e.g. Asher et al – Kepler, R(BD)=0.833+-0.021Rjup, consistent with models for age>1Gyr.... WTS?)

  5. Whyisspectroscopyso important? • Benchmark systems • Moving groups and clusters – young population, known age, metallicity • e.g. Wide companions – constrain age, metallicity, distance • Parallax measurements for faint (UCD) and brighter (primary) objects • Sub-giants & WDs particularly good • Triple systems even better (e.g. Companion = WD+star unresolved binary)

  6. Facilities - what do we have? • Gemini NIRI: JHK one by one (e.g. LAS) • Gemini GNRIS: JHK simultaneous (e.g. LAS) • VLT Xshooter: optical+JHK simultaneous (e.g. LAS) • HST: for fainter things (e.g. VIKING) • Spitzer: mid IR (Warm for ~5yrs, e.g. LAS) • SOAR: JHK simultaneous (brighter objects) • LAMOST: optical (improved efficiency for multiple systems?, clusters?)

  7. Objects - What do weneed? • UCDs probing new parameter-space (lower Teff, outliers in age, metallicity etc) • More benchmarks with well constrained physical properties (age, metallicity, distance) • Full spectral coverage at good SNR = lots of telescope time • NB: WISE will give us mid-IR constraints for free • To give reliable Fbol -> Luminosity -> Teff+logg • Holy grail = a Teff/logg/[M/H] grid with full optical-NIR-midIR spectral coverage • -> Establish optimal spectroscopic method to determine atmospheric properties (Teff/logg/[M/H]) spectroscopically • -> Allow derivation of physical properties (mass, age, metallicity) spectroscopically • = IMF+BR+unprecedented test-bed for ultracool atmosphere models

  8. Discussion & follow-on actions… • Expand existing samples beyond UKIDSS+SDSS • New surveys (VIKING, VHS, WISE...) • New techniques on (e.g. Y-only, NIR out-liers which are optical non-detections...) • Exploiting all existing routes for spectroscopic follow-up of samples • New collaborative proposals for spectroscopic follow-up

  9. Thanks for your attention

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