new probes of substellar evolution from infrared parallax program(s) new probes of substellar...

New Probes

of Substellar Evolution

from Infrared Parallax Program(s)

Trent Dupuy

Art credit: R. Hurt (IPAC)

Trent Dupuy (CfA/SAO)

log(L b

Mass (M)

Hubble Symposium 2012

log(L b

Saumon & Marley (2008) “hybrid” tracks

Dahn et al. (2002), Tinney et al. (2003), Vrba et al. (2004), etc.

Main-sequence stars

Brown dwarfs Colder = dustier

Colder = more methane-rich

Dust clouds disperse

energy output= mass

Hubble Symposium 2012Trent Dupuy (CfA/SAO)

Main-sequence stars

Brown dwarfs

L/T transition

late-T

energy output= mass

Main-sequence stars

Brown dwarfs

energy output= mass

>M6dynamical

masses

Dynamical Masses for Visual Binaries

Kepler

P2 =α3d3

Mass (M)

10 Gyr

0.3 Gyr

0.1 Gyr

>M6≈3% distance≈10% mass

≈10% distance≈30% mass

starsbrown dwarfs“planetary mass”

Baraffe et al. (2003) COND tracks

USNO opticalPI: Dahn, Monet

Previously published parallaxes for L and T dwarfs

USNO IRPI: Vrba

NTT/SOFIPI: Tinney

Precision needed for ultracool binary masses

Trent Dupuy (CfA/SAO) Hubble Symposium 2012

CFHT Parallax Program - queue scheduled - Mauna Kea seeing - 3.6-m aperture - WIRCam’s large FOV

Credit: J.-C. Cuillandre (CFHT)

WIRCam ObservingStrategy

• use a single chip

• get ≈20−30 dithered frames per epoch

• J-band: always observe within ≈1 hr of transit (queue is ideal for this)

- OR -• narrow K-band for bright targets – no DCR

differential chromatic refraction

Δairmass < 0.03

Δairmass = 0.2

1. pixel coordinates of sources2. date/time (header)

WIRCam AstrometricAnalysis

• run SExtractor on the detrended images (no stacking!)

• cross-match sources between dithers

Apply custom distortion solution before solving for linear terms.(Also applied differential aberration and refraction offsets: 10-4 change to scale.)

• register dithers without using any catalog info

(i.e., ≈0.04 pixels)(i.e., ≈0.009 pixels)

divide by sqrt(Ndither)

• register dithers without using any catalog info

• compute median and rms of source positions

• Markov Chain Monte Carlo parallax fitter

• orbit motion correction applied to binaries with known orbits

• absolute parallax correction derived from Besancon Galaxy model

• c2 good for all targets, except 3 new astrometric binaries!

Parallax fits for 45 targets(79 objects)

CFHT parallaxes

median: 1.3 mas (2.5%)best: 0.7 mas (1.0%)

Combine new parallaxes with loads of Keck

LGS AO imaging (17 binaries)

And IRTF spectra…

Perform “spectral decomposition” for

all binaries with resolved near-IR photometry and

int.-light spectrum.(33 binaries)

Main-sequence stars

Brown dwarfs

M6−L2L2.5−L9L9.5−T4T4.5−T9

1. “L/T gap”

2. late-T dwarf diversity 3. J-band brightening

(a.k.a. “bump”)

The L/T “gap”

Paucity of brown dwarfs at certain J-H and J-K colors, but not H-K.

Implies that the last phase of cloud dispersal

occurs rapidly.

The L/T “gap”

Saumon & Marley (2008)

gap pileup

May also be tied to a theoretically predicted (but as yet unobserved)

lag and speed-up in luminosity evolution…

M6−L2L2.5−L9L9.5−T4T4.5−T9

1. “L/T gap”

2. late-T dwarf diversity

Trent Dupuy (CfA/SAO) Hubble Symposium 2012

rms about the polynomial fit in mags

“second” parameters like metallicity, gravity have bigger effect on T dwarfs than for earlier types…

M6−L2L2.5−L9L9.5−T4T4.5−T9

1. “L/T gap”

2. late-T dwarf diversity 3. J-band brightening

(a.k.a. “bump”)

J-band “bump”≈0.7 mag

H-band plateau≈0.0 mag

Y-band “bump”≈0.9 mag

Dust clearing has an even bigger

effect at ≈1.0 mm than at ≈1.2 mm.

Results Summary• CFHT parallaxes (paper 1):

– doubles sample of binaries, ≈tripled L/T transition sample– median (best) precision of 1.3 mas (0.7 mas) or 2.5% (1.0%)– 3 binaries w/ astrometric perturbations (1 new discovery)– Lots of extra data:

• Keck LGS AO + archival HST, VLT imaging• IRTF spectra (spectral decomposition analysis)

• New science with populous sample of ultracool dwarfs:– “L/T gap” observed for the first time– populous late-T sample reveals important 2nd parameters – J-band (and now Y-band) “bump”

High-precisionfor faint targets

1995 2002 20082010

Gl 570D

700 K700 K

550 K520 K

2M0415

CFBDS 0059UGPS 0722

CFBDSIR 1458BWD 0806-661B

Brown Dwarf Discoveries at 300 K?

Extremely cold companion discovered in our Keck LGS AO imaging

Warm Spitzer parallaxes of “room temperature” WISE Y-type dwarfs

Cycle 8 DDT Programco-Is: A. Kraus, M. Liu

Hubble Symposium 2011 @ Caltech(a.k.a. Apple’s next iPhone ad)

Thank You

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