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Near-IR Spectral Properties of Young Brown Dwarfs

Near-IR Spectral Properties of Young Brown Dwarfs. Katelyn Allers, IfA-Hawaii. Mike Liu Mark Pitts Jonathan Leong Joan Najita Alan Tokunaga. Kelle Cruz Davy Kirkpatrick Adam Burgasser Greg Doppmann Dan Jaffe Kevin Luhman. Why should we search for young brown dwarfs?.

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Near-IR Spectral Properties of Young Brown Dwarfs

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  1. Near-IR Spectral Properties of Young Brown Dwarfs Katelyn Allers, IfA-Hawaii • Mike Liu • Mark Pitts • Jonathan Leong • Joan Najita • Alan Tokunaga Kelle Cruz Davy Kirkpatrick Adam Burgasser Greg Doppmann Dan Jaffe Kevin Luhman

  2. Why should we search for young brown dwarfs? • Exploring the low mass end of the IMF • Formation Mechanism: Ejection vs. Isolated Collapse • Disks around the lowest-mass objects Image Credits: NASA/HST; NASA/JPL-Caltech/T. Pyle

  3. Mass (A) MJup Mass (B) MJup 65±30 35±20 14±1 7±0.5 17.5±2.5 15.5±2.5 55±10 19±10/5 Not So Fast! Oph1622-2405 A & B

  4. dist BC AV Model Spectrum SpT Observed Spectrum Photometry Teff L*

  5. Just the M8’s

  6. Determining Gravity The 1.14 micron Na doublet is gravity sensitive, and through the late-M and early-L types is only weakly dependent on SpT.

  7. Na (1.14) K (1.169) K (1.177) K (1.253) TWA 3.87 0.75 1.73 0.50 2.47 0.32 1.60 0.26 Young 2.96 0.54 0.98 0.21 1.78 0.22 1.15 0.36 Is there an age (gravity) spread? Line EW’s

  8. Determining SpT Even though the overall shapes of the H-band differ, the slope of the blue end of the H-band is SpT sensitive, yet gravity insensitive.

  9. A Custom Filter for Determining SpT • Central wavelength: 1.45 microns • Filter width = 6% • Estimated Sensitivity: • H=19.9 mag (10 in 1 hour) • W~18.0 mag (10 in 1 hour) • Designed for 1.0 subtype uncertainty in SpT determination for 5% photometric accuracy W-band detections. • Designed for use in 1-5mm of pwv (Mauna Kea) J W H

  10. Conclusions • We need more young cluster and young field objects in analysis! (Please?) • Na and K lines are better gravity indicators than the shape of the H-band continuum • We don’t see an age spread indicated in the alkali line EW’s. • The 1.45 micron steam absorption feature is very sensitive to SpT.

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