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Present: LGA+AO @ Gemini Observatory, Mauna Kea

Revealing the Environments of Young Brown Dwarfs Using Spectral Imaging. Present: LGA+AO @ Gemini Observatory, Mauna Kea. Tracy L. Beck Space Telescope Science Institute Baltimore, MD. Future: JWST @ L2 in 2014. First: What Flavor of “Spectral Imaging”?.

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Present: LGA+AO @ Gemini Observatory, Mauna Kea

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  1. Revealing the Environments of Young Brown Dwarfs Using Spectral Imaging Present: LGA+AO @ Gemini Observatory, Mauna Kea Tracy L. Beck Space Telescope Science Institute Baltimore, MD Future: JWST @ L2 in 2014

  2. First: What Flavor of “Spectral Imaging”? High Contrast, High Spatial Resolution Spectroscopy Techniques: • Longslit Spectroscopy • Step a longslit across an astronomical target • Very inefficient • Narrow-band Filter Imaging • Very low spectral resolution, poor continuum subtraction • Fabry-Perot Interferometry • Wide field high resolution spectral imaging, but small wavelength coverage • Integral Field Spectroscopy with Integral Field Units (IFUs) provide simultaneous resolved imaging spectroscopy in small 2-D imaging fields

  3. Telescope focus Spectrograph input Spectrograph output Pupil imagery Lenslets, OSIRIS (Keck) Datacube slit y Lenslets + fibres GMOS (Gemini) VIMOS (VLT) Fibres  x 1 Image Slicer GNIRS, NIFS (Gemini), SPIFFI+SINFONI (VLT) slit Mirrors 2 3 4 1 2 3 4 Integral Field Spectroscopy - NOT Just for Extragalactic Science! + AO Allows for high Spatial resolution (~14AU) Study of IR emission Lline features NIFS 3” 3” Figure courtesy of J. Allington-Smith (U. of Durham)

  4. The Near Infrared Integral Field Spectrograph (NIFS) at Gemini North Observatory, Mauna Kea • Near IR, AO-fed image slicing IFU for 1.0-2.5 micron spectra • R~5000 spectroscopy • 3” x 3” field with 0.”1x0.”04 (rectangular) Spatial Sampling • 1 pointing gives IFU spectra over one full IR band (Z, J, H or K) NIFS 3” R~5000 3” Individual Pixel Size 0.”04 0.”10

  5. How are IFUs Useful for Brown Dwarf Science?? An Intro to IRAS 04158+2805 • A closer look at the young, BD candidate - IRAS 04158+2805 • IRAS 04158 is seen in the optical largely in scattered light, with a ‘bipolar’ nebula structure typical of opaque disk material along the mid-plane (Glauser et al. ‘08) • It has an extended circum-source disk, inclined by ~63o From Glauser et al. 2008

  6. How are IFUs Useful for Brown Dwarf Science? IRAS 04158+2805 • Optical & IR Spectroscopy = M6 type (Beck 2007; Luhman 2006; White & Hillenbrand 2004) • Large discrepancies in estimated Av, Luminosity of very young sources is notoriously difficult to derive. • K-band (2.0-2.4m) IR spectrum with ‘best-fit’ from spectral template modeling (Beck 2007)

  7. Seiss et al. ‘00 IRAS 04158+2805… • Source is evolving vertically in the HR diagram, down Hayashi track (precise L* not so important) • YOUNG!!!! (<~1Myo!) • M6 type, commonly adopted SpT for young BD limit • HR Diagram fitting = substellar ~0.05Msolar (large unc’ty in models) • “BD Candidate” Baraffe et al. ‘98

  8. IRAS 04158+2805 • Andrews et al (‘08) detected the disk in sub-mm, high spatial resolution dust continuum and CO gas! • 883 m continuum dust emission extends out to >~500AU from the central source. • IRAS 04158 is a very young (<~1Myo) low mass star / BD candidate with a HUGE, extended ~1000+ AU diameter circumstellar disk • Measurement of weak signal of Keplerian motion in CO gas suggests that central source may be more massive than a single brown dwarf (stellar or binary BD). • Mdisk / Mstar could be ~20%! Much less than ~2-4% for T Tauri stars. Disk may be gravitaionally unstable. From Andrews et al. 2008

  9. How are IFUs Useful for Brown Dwarf Science? IRAS 04158+2805 • Low resolution IR Spectra show 2.12 micron molecular Hydrogen emission from this young, BD candidate! • Is this perhaps Quiescent emission from the candidate BD’s circumstellar disk? • K-band (2.0-2.4m) IR spectrum with ‘best-fit’ from spectral template modeling (Beck 2007)

  10. Gemini + NIFS Laser-Fed AO IFU Spectroscopy of IRAS 04158+2805 • R~5000 spatially resolved IFU spectroscopy, allows for *Extremely* accurate subtraction of continuum flux, from simultaneous multi-wavelength measurement of continuum (this is why GPI and next-gen planet hunting instruments will incorporate low-R IFUs) Model and Subtract out continuum flux, repeat for all ~1000 IFU spectra in the datacube to form a 2-D emission line image

  11. Laser-fed AO Spectral Imaging, IRAS 04158+2805 100 AU 1.644m [Fe II] (Reveals a Jet in Atomic Emission) 2m K-band (Scattered Light from the Disk Surface ) 2.12m H2 (Wide-Angle Outflow) • Goal - Determine if H2 gas traces disk material in the BD candidate environment - it doesn’t! • Data reveals that the H2 encompasses the Fast, on-axis outflow! • BLUE-shifted, collimated [Fe II] jet associated with the brighter lobe of the scattered light nebulosity - no redshifted jet detected • Jet Orientation consistent w/ 63o disk inclination

  12. Laser-fed AO Spectral Imaging, IRAS 04158+2805 100 AU 1.644m [Fe II] (Reveals a Jet in Atomic Emission) 2m K-band (Scattered Light from the Disk Surface ) 2.12m H2 (Wide-Angle Outflow) • Observational studies now suggest strong commonalities between the early evolution of some brown dwarfs and higher mass YSOs: • Circumstellar Disks (Wilking 1999; Natta 2002; Andrews 2008) • Mass Accretion Activity (Natta et al. 2004) • Only a small number (~4) have previously shown evidence for mass outflow (Whelan et al. 2007; 2009; Bourke et al.) • This data on IRAS 04158+2805 is the first 2-D spatially resolved image of a T Tauri-like micro-jet from a young, M6 spectral type BD candidate

  13. Ground-Based Laser-Fed AO Spectral Imaging of BD Environments • Lesson: Laser-Fed AO on large ground-based telescopes is a powerful means to reveal the inner environments of young BDs at high spatial resolution using IR emission lines… • Complication: BDs are optically very faint, but you need an optical tip-tilt guide star! (TTGS) • Observations of IRAS 04158+2805 were only possible with LGS AO because of the nearby r~17.6 magnitude guide star TTGS r~17.6mag IRAS 04158+2805 K~11.6 mag, R~21 AO TTGS Area Gemini Observing Tool View

  14. Spectral Imaging of BD Environments with JWST The James Webb Space Telescope The James Webb Space Telescope - operating at L2 in 2014 • 6.5m Segmented Primary • 4 Science Instruments: • NIRCam - Near-InfraRed Camera • NIRSpec - Near-InfraRed Spectrograph • TFI - Tunable Filter Imager • MIRI - Mid-InfraRed Instrument (M. Clampin’s talk, Tuesday) A schematic view of the JWST focal plane, including the placement of the science entrance apertures for each instrument. NIRSpec and MIRI have Integral Field Units for very sensitive high-contrast imaging spectroscopy of brown dwarf environments.

  15. JWST + NIRSpec - Future Option for Science on BDs and EPs A schematic of the NIRSpec layout, projected onto the detector plane. NIRSpec will observe 0.7-5m R=100, 1000 or 2700 spectroscopy in up to a ~3’ x ~3’ field with: • Multi-Object mode using the fixed, 4 quadrants of Micro-shutter arrays (MSAs) - for projects such as confirming free-floating Brown Dwarfs in clusters • fixed-slit spectroscopy using 4 longslits or a high S/N 1.”6 square wide aperture, for pointed spectroscopy, particularly for planet transit spectroscopy (limit effects of drift and telescope jitter) • or IFU spectroscopy to characterize young BD environments using high-contrast emission line spectral imaging (3” x 3” field) NIRSpec will be a prime instrument for measuring exoplanet spectra using NIR transit spectroscopy!

  16. JWST + NIRSpec - Future Option for Science on BDs and EPs JWST NIRSpec Instrument Characteristics and Science Modes: NIRSpec Predicted Sensitivity: S/N ~10 on continuum in R=100 mode on a point source of brightness 23rd mag at 3m in 10,000s exposure time (~2.8 hrs)

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