Huddled&Masses&Yearning&to& Breathe&Free&&pono.ucsd.edu/~adam/presentations/0910princeton.pdf ·...

Huddled Masses Yearning to Breathe Free Unresolved Brown Dwarf Binaries Iden:fied with Low Resolu:on Near-‐Infrared Spectroscopy

Adam J. Burgasser UC San Diego/MIT

© 2009 Adam J. Burgasser

WHAT IS THE BROWN DWARF MULTIPLICITY

FRACTION IN THE FIELD?

10%?

20%?

50%?


Bate et al. (2009): 5-‐20% Lada (2006): 5-‐15%

Thies & Kroupa (2007): 5-‐15% © 2009 Adam J. Burgasser

Bate et al. (2009): 5-‐20% Lada (2006): 5-‐15%

Thies & Kroupa (2007): 5-‐15%

“BD binary frac:ons are low” But are they?


Pinfield et al. (2003): 40-‐61%

Lodieu et al. (2007): 28-‐44%

Maxted & Jeffries (2005): 32-‐45%


hcp://www.vlmbinaries.org 10-2 100 102 104

Projected Separation (AU)

0

5

10

15

20

25

30

Num

ber

of S

ourc

es

VLM Binaries Archive 93 sources ~4 AU


hcp://www.vlmbinaries.org 10-2 100 102 104 106

Angular Separation (marcs)

0

5

10

15

20

25

30

Num

ber

of S

ourc

es

VLM Binaries Archive 90 sources

50 mas


hcp://www.vlmbinaries.org 10-2 100 102 104 106

Angular Separation (marcs)

0

5

10

15

20

25

30

Num

ber

of S

ourc

es

VLM Binaries Archive 90 sources

50 mas

How many sources live

here?


Standard Ways to Find Tight BD Binaries

•  Radial velocity variables (e.g., Joergens 2006,2008; Basri & Reiners 2006; Blake et al. 2008) Pros: samples :ght physical separa:ons (

Spectral Binaries

Silvestri et al. (2006) WD-‐dM unresolved pair

Combined light spectra of dis:nct but comparably bright components

Pros: independent of angular & projected separa:on, can be done with low-‐resolu:on data (cheap), can characterize components

Cons: rare, no separa:on info, complex selec:on effects


Spectral Binaries

Silvestri et al. (2006) WD-‐dM unresolved pair

Combined light spectra of dis:nct but comparably bright components

Pros: independent of angular & projected separa:on, can be done with low-‐resolu:on data (cheap), can characterize components

Cons: rare, no separa:on info, complex selec:on effects

Spectral binaries are easily iden:fiable at the

L dwarf/T dwarf transi:on


The L dwarf/ T dwarf Transi:on*

*Spectral types L7-‐T5 1.0 1.5 2.0Wavelength (!m)

0

1

2

3

4

5

Nor

mal

ized

F

L7

L8

L9

T0

T1

T2

T3

T4

T5

ΔTeff ≈ 200-‐400 K ΔLbol ≈ 0.3 dex


The J-‐band bump

J-‐Ks color

MJ

Burrows et al. (2006) See also Dahn et al. (1999); Ackerman & Marley (2001); Marley et al. (2002); Tinney et al. (2003); Tsuji (2003,2005); Saumon & Marley (2008) © 2009 Adam J. Burgasser

Looper et al. (2008); Burgasser et al. (2006) See also Gizis et al. (2003); Cruz et al. (2004); Liu et al. (2006); Burgasser (2007,2008)

Primary Secondary

Combined Light Data

J

H

Ks

The J-‐band bump

Detected in resolved coeval binaries as well

2M 1404-‐3159 SD 0423-‐0414


Exploi:ng the L/T Transi:on “J-‐band” bump Deep minimum in LF

An enhanced binary frac:on of equal-‐

brightness components at the L/T transi:on


1.0 1.5 2.0Wavelength (µm)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

0518-2828

0825+2115 L7.5 (L7.0)

2331-4718 T5.0 (T5.0)

"2 = 58.9

2M 0518-‐2828 Archetype L/T Spectral Binary

Cruz et al. (2004); Burgasser et al. (2006)

Resolved (barely) with HST/NICMOS (50 mas ≈ 1.8 AU)


2M 0320-‐0446 An M/T Spectral/Spectroscopic Binary

Burgasser et al. (2008); Blake et al. (2008)

Spectroscopic binary with 0.67 yr period

(ΔV = ±7 km/s; M1 ≈ 0.08 M, M2 ≈ 0.05 M

ΔK = 4.3 mag


A Search for Unresolved L/T Binaries

•  Full sample of 253 SpeX prism spectra for 233 L3-‐T8 dwarfs from SpeX Prism Spectral Libraries*

•  Index selec:on of binary candidates •  Template library of 170 spectra (reject low g, subdwarfs, low S/N, known & candidate binaries)

•  Construct 13,581 unique binary combina:ons •  Compare single and binary templates to candidates and assess sta:s:cal significance of “becer fit”

* hcp://www.browndwarfs.org/spexprism © 2009 Adam J. Burgasser

Derived NIR Spectral Type

0.2

0.4

0.6

0.8

1.0

1.2

H2O

-J/H

2O

-H2252-1730 0423-0414

0423-0414

0518-2828

1404-3159

1021-0304

1534+1615

L0 L2 L4 L6 L8 T0 T2 T4 T6 T8

Index Selec:on

=> 20 candidates iden:fied (12 “strong” + 8 “weak”)

x6



0.0

0.2

0.4

0.6

0.8

1.0

1.2N

orm

aliz

ed F

!0247-1631

1520+3546 T0.0 (L7.5)

0050-3322 T7.0 (T6.5)

"2 = 1.99


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

0351+4810

0103+1935 L6.0 (L6.0)

0602+4043 T4.5 (T4.5)

"2 = 6.64


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

1039+3256

1043+1213 L7.0 (L8.0)

2254+3123 T4.0 (T4.0)

"2 = 2.56


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

1106+2754

1520+3546 T0.0 (L7.5)

0000+2554 T4.5 (T4.5)

"2 = 5.18


0.0

0.2

0.4

0.6

0.8

1.0

1.2

No

rmal

ized

F!

1324+6358

1043+2225 L8.0 (L9.0)

1214+6316 T3.5 (T4.0)

"2 = 6.17


0.0

0.2

0.4

0.6

0.8

1.0

1.2

No

rmal

ized

F!

1415+5724

1523+3014 L8.0 (L7.5)

0741+2351 T5.0 (T5.5)

"2 = 1.73


0.0

0.2

0.4

0.6

0.8

1.0

1.2

No

rmal

ized

F!

1435+1129

1043+1213 L7.0 (L8.0)

1615+1340 T6.0 (T6.0)

"2 = 19.9


0.0

0.2

0.4

0.6

0.8

1.0

1.2

No

rmal

ized

F!

1439+3042

0151+1244 T1.0 (T0.0)

2356-1553 T5.5 (T5.5)

"2 = 4.85


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

1516+0259

0318-3421 L7.0 (L6.5)

1048+0919 T2.5 (T2.5)

"2 = 1.97


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

1711+2232

0624-4521 L5.0 (L5.0)

1828-4849 T5.5 (T5.5)

"2 = 1.49


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

2139+0220

0830+4828 L9.0 (L9.5)

1214+6316 T3.5 (T4.0)

"2 = 1.83


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

0119+2403

0858+3256 T1.0 (T0.0)

2254+3123 T4.0 (T4.0)

"2 = 15.7


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

0909+6525

1750+4222 T2.0 (T1.5)

1048+0919 T2.5 (T2.5)

"2 = 2.53


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

0949-1545

1632+4150 T1.0 (T1.0)

1122-3512 T2.0 (T2.0)

"2 = 13.7


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

1207+0244

1036-3441 L6.0 (L6.5)

1209-1004 T3.0 (T3.0)

"2 = 6.14


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

2052-1609

1155+0559 L7.5 (L7.0)

1122-3512 T2.0 (T2.0)

"2 = 2.59



0.0

0.2

0.4

0.6

0.8

1.0

1.2N

orm

aliz

ed F

!0247-1631

1520+3546 T0.0 (L7.5)

0050-3322 T7.0 (T6.5)

"2 = 1.99


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

0351+4810

0103+1935 L6.0 (L6.0)

0602+4043 T4.5 (T4.5)

"2 = 6.64


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

1039+3256

1043+1213 L7.0 (L8.0)

2254+3123 T4.0 (T4.0)

"2 = 2.56


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

1106+2754

1520+3546 T0.0 (L7.5)

0000+2554 T4.5 (T4.5)

"2 = 5.18


0.0

0.2

0.4

0.6

0.8

1.0

1.2

No

rmal

ized

F!

1324+6358

1043+2225 L8.0 (L9.0)

1214+6316 T3.5 (T4.0)

"2 = 6.17


0.0

0.2

0.4

0.6

0.8

1.0

1.2

No

rmal

ized

F!

1415+5724

1523+3014 L8.0 (L7.5)

0741+2351 T5.0 (T5.5)

"2 = 1.73


0.0

0.2

0.4

0.6

0.8

1.0

1.2

No

rmal

ized

F!

1435+1129

1043+1213 L7.0 (L8.0)

1615+1340 T6.0 (T6.0)

"2 = 19.9


0.0

0.2

0.4

0.6

0.8

1.0

1.2

No

rmal

ized

F!

1439+3042

0151+1244 T1.0 (T0.0)

2356-1553 T5.5 (T5.5)

"2 = 4.85


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

1516+0259

0318-3421 L7.0 (L6.5)

1048+0919 T2.5 (T2.5)

"2 = 1.97


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

1711+2232

0624-4521 L5.0 (L5.0)

1828-4849 T5.5 (T5.5)

"2 = 1.49


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

2139+0220

0830+4828 L9.0 (L9.5)

1214+6316 T3.5 (T4.0)

"2 = 1.83


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

0119+2403

0858+3256 T1.0 (T0.0)

2254+3123 T4.0 (T4.0)

"2 = 15.7


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

0909+6525

1750+4222 T2.0 (T1.5)

1048+0919 T2.5 (T2.5)

"2 = 2.53


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

0949-1545

1632+4150 T1.0 (T1.0)

1122-3512 T2.0 (T2.0)

"2 = 13.7


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

1207+0244

1036-3441 L6.0 (L6.5)

1209-1004 T3.0 (T3.0)

"2 = 6.14


0.0

0.2

0.4

0.6

0.8

1.0

1.2

Norm

aliz

ed F

!

2052-1609

1155+0559 L7.5 (L7.0)

1122-3512 T2.0 (T2.0)

"2 = 2.59

We iden:fied 17/20 sources as probable binaries (index selec:on, becer fit to binary templates) – more than 2x known sample

3 are unresolved with HST/AO (Looper et al. 2008; Gelino et al. in prep)

2 have been subsequently resolved with AO (Gelino et al. in prep.)

12 are unobserved at high resolu:on


Spectral Type

0

20

40

60

80

Fra

ctio

n o

f B

ina

rie

s

L8 L9 T0 T1 T2 T3 T4 T5

0/12 (21) 1/9 (13) 6/9 (14) 6/10 (15) 8/17 (20) 3/7 (13) 1/10 (20)

eb = 15%

What about the binary frac:on?

53±7%

eb ≥ 15+3-‐1 %


Conclusions

•  Spectral binaries comprised of L dwarf/T dwarf pairs can measure the intrinsic BD binary frac:on

–  Indep. of physical separa:on (:ght pairs; e.g. 2m0320)

–  Indep. of angular separa:on (distant pairs, large samples)

–  Can be done cheap and fast with low-‐res spectral data

•  We have uncovered 17 (+3) probable binaries; a few confirmed, most awai:ng follow-‐up

•  The BD binary frac:on is ≥15% independent of separa:on distribu:on


Huddled Masses Yearning to Breathe Free Unresolved Brown Dwarf Binaries Iden:fied with Low Resolu:on Near-‐Infrared Spectroscopy

Adam J. Burgasser UC San Diego/MIT


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