The Galactic Orbits of Ultracool Subdwarfs Adam J. Burgasser UC San Diego/MIT
Robyn Sanderson (MIT) Adam Burgasser, Andrew West, John Bochanski (MIT) and Jackie Faherty (AMNH/SUNY Stony Brook) Nitya Kallivayalil 2009 (MIT) Adam J. Burgasser
Background & Motivation Orbit Calculations & Spectral Model Fits Results & Future Directions
What are Ultracool Subdwarfs?
What are Subdwarfs? What are What are ultracool Why study ultracool Kuiper (1939); Joy (1947) also Adams & Joy (1922); Adams (1935); Kuiper (1940); Chamberlain & Aller (1951)
Metallicity Effects in Subdwarf Spectra Metal- poor What are What are ultracool Why study ultracool Metal- rich Lepine et al. (2003) see also Mould (1976); Gizis & Reid (1997); Burgasser et al. (2006)
Metallicity Effects in Subdwarf Spectra What are What are ultracool Why study ultracool dwarfs subdwarfs extreme subdwarfs ultra subdwarfs Lepine, Rich & Shara (2007) also Gizis (1997); Burgasser & Kirkpatrick (2006)
Metallicity Effects in Subdwarf Spectra Metallicity What are What are ultracool Why study ultracool Temperature Lepine, Rich & Shara (2007) also Jao et al (2008)
Subdwarfs have Halo Kinematics What are What are ultracool Why study ultracool Cushing et al. (2009) also Gizis (1997); Lepine et al. (2004); Burgasser et al. (2008,2009)
What are Ultracool Subdwarfs? sdm8 sdm8.5 What are What are ultracool Why study ultracool sdm9.5 sdl4 sdl7 Ultracool subdwarfs are sources typed sdm7/esdm7/ usdm7 or later, and have T eff 3000 K Burgasser et al. (2008) also Gizis & Harvin (2007)
Cooler is Cloudier What are What are ultracool Why study ultracool Kirkpatrick et al. (1999); Burgasser et al. (2008) also Cushing 2009 et Adam al. (2006) J. Burgasser
L subdwarfs What are What are ultracool Why study ultracool Burgasser et al. (2003) also Burgasser (2004); Cushing et al. (2008)
Highly sensitive probes of metallicity 1.5 1.0 M0 M1 M2M3 M4 M5 M6 M7 M8 M9 L0 What are What are ultracool Why study ultracool LSR 1425+7102 0.5 2MASS 0142+0523 0.0 3500 J-K s 0.0 3400 3300 3200 3100 3000 SSSPM J1013-1356 SDSS J1256-0256 2MASS J0532+8246-0.5 2MASS J1626+3925 2900 2800-1.0 2700-0.5-1.0 2600 2500 2400 2300 2200 2100 2000-2.5-2.0-1.5 GAIA Cond-Phoenix models log g = 5.5 1 2 3 4 5 6 i -J Burgasser et al. (2009) also Scholz et al. (2004); Dahn et al. (2008); Schilbach et al. (2009)
Sample the Z-dependent stellar/substellar boundary 2M 0532+8246 sdl7 What are What are ultracool Why study ultracool Burgasser et al. (2008)
Examine Z-dependent chemistry in cool atmospheres What are What are ultracool Why study ultracool Witte et al. (2009) also Burrows et al. (2006) Do condensates clouds form in metal-poor atmospheres?
Orbits & Atmospheres: Motivation
Motivation: Different Properties of Inner/Outer Halo Inner/Outer Halo Kinematics & Colors in UCDs Galactic Streams & Substructure Program Outline Carollo et al. (2007) also Searle & Zinn (1978); Sommer-Larson & Zhen (1990); Chiba & Beers (2000)
Motivation: Kinematics & Atmospheres in Ultracool Dwarfs Inner/Outer Halo Kinematics & Colors in UCDs Galactic Streams & Substructure Program Outline Faherty et al. (2009) also Zapatero Osorio et al. (2007); Jameson et al. (2008)
Streams & Galactic Substructure Inner/Outer Halo Kinematics & Colors in UCDs Galactic Streams & Substructure Program Outline Belokurov et al. (2006); Klement et al. (2009) also Ibata et al. (1994); Majewski et al. (1999); Helmi (2008 review)
Orbits & Atmospheres: Ingredients Calculate Galactic orbits of UCSDs and examine constants of motion Identify distinct halo populations Inner/Outer Halo Kinematics & Colors in UCDs Galactic Streams & Substructure Program Outline Search for streams/groupings Determine atmospheric parameters Teff, [M/H], log g, clouds Search for correlations
Orbits
Gathering data positions and velocities Data Gathering Potential Models Variety of orbits Extrema Conserved Quantities Cushing et al. (2009); Schilbach et al. (2009) also Monet et al. (1995); Burgasser et al. (2008); Dahn et al. (2008)
Calculating Galactic Orbits 6 5 Enclosed Mass in Model I Data Gathering Potential Models Variety of orbits Extrema Conserved Quantities 4 disk M 10 10 Msun 3 bulge halo 2 total 1 0 0 2 4 6 8 10 12 r kpc Models I and II from Binney & Tremaine (2008)
Calculating Galactic Orbits 6 5 Enclosed Mass in Model II Data Gathering Potential Models Variety of orbits Extrema Conserved Quantities 4 disk M 10 10 Msun 3 bulge halo 2 total 1 0 0 2 4 6 8 10 12 r kpc Models I and II from Binney & Tremaine (2008)
Galactic Orbits: Wide Diversity Data Gathering +%&'()*!" # "!# 1%&'()*, -. / "!/!. Potential Models Variety of orbits Extrema Conserved Quantities!!"!!"!# " #!" $%&'()*!-!, " #!" 0%&'()*!/, 0%&'()*!", -. / "!#"" " #""?@><%&:A5* 1%&'()* -. / "!/!.!-!,!#"" " #""?@><%&:A5* Sanderson et al. (in prep.)
Galactic Orbits: Wide Diversity Data Gathering!" # ",- ",. Potential Models Variety of orbits Extrema +%&'()* " 0%&'()* " Conserved Quantities!#!",.!!"!!"!# " #!" $%&'()*!",- " #!" /%&'()*!. ",:!" ",. /%&'()* A 8 -. "!#"" " #"" BC6?%&<D4* 0%&'()* ",! "!",!!",.!",:!",-!#"" " #"" BC6?%&<D4* Sanderson et al. (in prep.)
Galactic Orbits: Wide Diversity Data Gathering. Potential Models *$%&'()! " 0$%&'() -, + "!+ Variety of orbits Extrema Conserved Quantities!!!,!-!! "! #$%&'()!. " +, -. /$%&'() /$%&'(). -, + "!!"" "!"" @A6>$%;B4) 0$%&'(). -, + "!+!,!-!.!!"" "!"" @A6>$%;B4) Sanderson et al. (in prep.)
Galactic Orbits: Extremum LSR 1610-004 Star: lsr1610!0040 Model: m4 Data Gathering 5 Potential Models 5 Variety of orbits Extrema Y (kpc) 0 Z (kpc) 0 Conserved Quantities!5!5 0 5 X (kpc)!5 0 5 10 R (kpc) 8 5 6 R (kpc) 4 Z (kpc) 0 2 0!500 0 500 Time (Myr)!5!500 0 500 Time (Myr) Sanderson et al. (in prep.)
Galactic Orbits: Extremum 2M 1227-0447 Star: 2mass1227!0447 Model: m4 Data Gathering 50 20 10 Potential Models Variety of orbits Extrema Y (kpc) 0 Z (kpc) 0 Conserved Quantities!10!50!50 0 50 X (kpc)!20 0 20 40 60 R (kpc) R (kpc) 70 60 50 40 30 20 10 0!1000!500 0 500 1000 Time (Myr) Z (kpc) 10 5 0!5!10!15!20!1000!500 0 500 1000 Time (Myr) Sanderson et al. (in prep.)
LSR 1610-0040 2M 1227-0447 Sun From +Z From +X
Conserved Quantities Data Gathering Potential Models 3 10 6 2 10 6 2M 1227-0447 prograde Variety of orbits Extrema Conserved Quantities 1 10 6 L z (km 2 s -1 ) 0-1 10 6-2 10 6-3 10 6 d/sd sd esd usd 2M 0616-6407 retrograde 1.0 0.8 0.6 0.4 Eccentricity Sanderson et al. (in prep.)
Spectral Model Fits
Spectral Model Fitting: Near-Infrared is Best Normalized f! 1.2 1.0 0.8 0.6 0.4 0.2 0.0 1.2 1.0 0.8 1.0 1.5 2.0 Wavelength (µm) SDSS J1256-0256 GAIA Cond-Phoenix model T eff = 2300 K log g = 5.5 (cgs) [M/H] = -1.0 " = 0.51 Near-infrared Normalized f! 0.6 0.4 SDSS J1256-0256 GAIA Cond-Phoenix model T eff = 2300 K log g = 5.5 (cgs) [M/H] = -1.5 " = 2.25 Motivation Results Orbits & Atmospheres Exemplary Cases Red Optical Burgasser et al. (2008) Drift-Phoenix models by Helling et al. (2008) 0.2 0.0 6500 7000 7500 8000 8500 9000 Wavelength (Angstroms)
Results: The Good Motivation Results 1.0 2MASS 1227-0447 T = 2900 K Orbits & Atmospheres 0.8 [M/H] = -2.0 log g = 5.0 (cgs) Exemplary Cases Normalized F! 0.6 0.4 " 2 = 6.06 DOF = 111 0.2 0.0-0.5 0.0 1.0 1.5 2.0 Wavelength (µm) [M/H] -1.0-1.5-2.0 0.100 0.001 0.010 0.500 0.001 Burgasser et al. (in prep) -2.5-3.0 2000 2500 3000 3500 T eff (K) 0.010
Results: The Good Motivation Results 1.0 2MASS 1626+3925 T = 2200 K Orbits & Atmospheres 0.8 [M/H] = -1.0 log g = 5.5 (cgs) Exemplary Cases Normalized F! 0.6 0.4 " 2 = 141. DOF = 111 0.2 0.0-0.5 0.001 0.0 1.0 1.5 2.0 Wavelength (µm) [M/H] -1.0-1.5-2.0 0.010 0.100 0.001 0.500 Burgasser et al. (in prep) -2.5-3.0 2000 2500 3000 3500 T eff (K)
0.001 Results: The Ugly Motivation Results 1.0 LSR 1610-0040 T = 2900 K Orbits & Atmospheres 0.8 [M/H] = -0.5 log g = 5.0 (cgs) Exemplary Cases Normalized F! 0.6 0.4 " 2 = 1035 DOF = 111 0.2 0.0 1.0 1.5 2.0 Wavelength (µm) [M/H] 0.0-0.5-1.0-1.5-2.0 0.001 0.010 0.100 0.500 Burgasser et al. (in prep) -2.5-3.0 2000 2500 3000 3500 T eff (K)
Results: The Ugly Normalized F! 1.0 0.8 0.6 0.4 LSR 0822+1700 T = 3300 K [M/H] = -2.5 log g = 5.0 (cgs) " 2 = 4.88 DOF = 111 Motivation Results Orbits & Atmospheres Exemplary Cases 0.2 0.0 Burgasser et al. (in prep) 1.0 1.5 2.0 Wavelength (µm) [M/H] 0.0-0.5-1.0-1.5-2.0-2.5 0.001 0.010 0.500-3.0 2000 2500 3000 3500 T eff (K) 0.100 0.500 0.010 0.001
Temperature v. Spectral Type 3500 3000 d/sd sd esd usd Motivation Results Orbits & Atmospheres Exemplary Cases T eff (K) 2500 2000 M6 M7 M8 M9 L0 L1 L2 L3 L4 L5 L6 L7 Spectral Type Burgasser et al. (in prep.)
Metallicity v. Metallicity Type Motivation Results [M/H] 0.0-0.5-1.0 d/sd sd esd usd Orbits & Atmospheres Exemplary Cases -1.5-2.0-2.5 0.8 0.6 0.4 0.2! Burgasser et al. (in prep.)
Eccentricity v. [M/H] 1.0 0.8 Motivation Results Orbits & Atmospheres Exemplary Cases Eccentricity 0.6 0.4 d/sd sd esd usd 0.0-0.5-1.0-1.5-2.0-2.5 [M/H] Burgasser et al. (in prep.)
Inclination v. [M/H] Inclination (degrees) 40 30 20 10 0 d/sd sd esd usd 0.0-0.5-1.0-1.5-2.0-2.5 [M/H] Motivation Results Orbits & Atmospheres Exemplary Cases Burgasser et al. (in prep.)
Angular Momentum v. [M/H] L z (km 2 s -1 ) 3 10 6 2 10 6 1 10 6 0 2M 1227-0447 d/sd sd esd usd Motivation Results Orbits & Atmospheres Exemplary Cases -1 10 6 0.0-0.5-1.0-1.5-2.0-2.5 [M/H] Burgasser et al. (in prep.)
usdm8.5 2M 1227-0447: a Stream Star? Motivation Results Orbits & Atmospheres Exemplary Cases Anticenter Stream (Grillmair et al. 2008) Several streams are prograde, [Fe/H] -2...-1 and reside entirely within 50 pc of the Sun Is 2M 1227-0447 a tracer of one? GD-1 Stream (Willett et al. 2009)
sd?m6pec LSR 1610-0040: Peculiar for Orbital Reasons? Motivation Results Orbits & Atmospheres Exemplary Cases Does an orbit plunging deep into the center of the Galaxy explain LSR 1610-0040 s peculiarities? Dahn et al. (2008) also Lepine et al. (2003); Reiners & Basri (2006); Cushing et al. (2006)
Summary
SUMMARY Ultracool subdwarfs display a wide variety of orbits prograde & retrograde, circular to highly elliptical, inclined to planar and sample the inner & outer halos There are very weak correlations between atmospheric and orbital properties, possibly obscured by uncertainties Orbital properties may explain origins of ultra-fast mover 2M 1227-0447 and peculiar LSR 1610-0040
FUTURE WORK Improve distances and RVs for known UCSDs FIRE spectrograph Explore action space in detail (J, J p ), compare with known streams Dedicated search for UCSDs SDSS, UKIDSS, PanSTARRS, SkyMapper, LSST Improved spectral models particularly for optical diagnostics (metal H bands, opacities) Apply to other populations
The FIRE Spectrograph Near-infrared Echellette for the Magellan Telescopes 0.85-2.35 µm in a single image λ/δλ~6000 cross-dispersed (50 km/s; 0.6 slit) λ/δλ~1000-2500 prismdispersed (high throughput) Commissioning January 2009 Simcoe, Burgasser, Schechter et al. (2008) Don t forget the swag!
FUTURE WORK Improve distances and RVs for known UCSDs FIRE spectrograph Explore action space in detail (J, J p ), compare with known streams Dedicated search for UCSDs SDSS, UKIDSS, PanSTARRS, SkyMapper, LSST Improved spectral models particularly for optical diagnostics (metal H bands, opacities) Apply to other populations
The Galactic Orbits of Ultracool Subdwarfs Adam J. Burgasser UC San Diego/MIT