The Galactic Orbits of Ultracool Subdwarfs

Transcription

1 The Galactic Orbits of Ultracool Subdwarfs Adam J. Burgasser UC San Diego/MIT

2 Robyn Sanderson (MIT) Adam Burgasser, Andrew West, John Bochanski (MIT) and Jackie Faherty (AMNH/SUNY Stony Brook) Nitya Kallivayalil 2009 (MIT) Adam J. Burgasser

3 Background & Motivation Orbit Calculations & Spectral Model Fits Results & Future Directions

4 What are Ultracool Subdwarfs?

5 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)

6 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)

7 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)

8 Metallicity Effects in Subdwarf Spectra Metallicity What are What are ultracool Why study ultracool Temperature Lepine, Rich & Shara (2007) also Jao et al (2008)

9 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)

10 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)

11 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

12 L subdwarfs What are What are ultracool Why study ultracool Burgasser et al. (2003) also Burgasser (2004); Cushing et al. (2008)

13 Highly sensitive probes of metallicity M0 M1 M2M3 M4 M5 M6 M7 M8 M9 L0 What are What are ultracool Why study ultracool LSR MASS J-K s SSSPM J SDSS J MASS J MASS J GAIA Cond-Phoenix models log g = i -J Burgasser et al. (2009) also Scholz et al. (2004); Dahn et al. (2008); Schilbach et al. (2009)

14 Sample the Z-dependent stellar/substellar boundary 2M sdl7 What are What are ultracool Why study ultracool Burgasser et al. (2008)

15 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?

16 Orbits & Atmospheres: Motivation

17 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)

18 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)

19 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)

20 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

21 Orbits

22 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)

23 Calculating Galactic Orbits 6 5 Enclosed Mass in Model I Data Gathering Potential Models Variety of orbits Extrema Conserved Quantities 4 disk M Msun 3 bulge halo 2 total r kpc Models I and II from Binney & Tremaine (2008)

24 Calculating Galactic Orbits 6 5 Enclosed Mass in Model II Data Gathering Potential Models Variety of orbits Extrema Conserved Quantities 4 disk M Msun 3 bulge halo 2 total r kpc Models I and II from Binney & Tremaine (2008)

25 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.)

26 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.)

27 Galactic Orbits: Wide Diversity Data Gathering. Potential Models *$%&'()! " 0$%&'() -, + "!+ Variety of orbits Extrema Conserved Quantities!!!,!-!! "! #$%&'()!. " +, -. /$%&'() /$%&'(). -, + "!!"" 0$%&'(). -, + "!+!,!-!.!!"" Sanderson et al. (in prep.)

28 Galactic Orbits: Extremum LSR 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)! R (kpc) R (kpc) 4 Z (kpc) 0 2 0! Time (Myr)!5! Time (Myr) Sanderson et al. (in prep.)

29 Galactic Orbits: Extremum 2M Star: 2mass1227!0447 Model: m4 Data Gathering Potential Models Variety of orbits Extrema Y (kpc) 0 Z (kpc) 0 Conserved Quantities!10!50! X (kpc)! R (kpc) R (kpc) !1000! Time (Myr) Z (kpc) !5!10!15!20!1000! Time (Myr) Sanderson et al. (in prep.)

30 LSR M Sun From +Z From +X

31 Conserved Quantities Data Gathering Potential Models M prograde Variety of orbits Extrema Conserved Quantities L z (km 2 s -1 ) d/sd sd esd usd 2M retrograde Eccentricity Sanderson et al. (in prep.)

32 Spectral Model Fits

33 Spectral Model Fitting: Near-Infrared is Best Normalized f! Wavelength (µm) SDSS J GAIA Cond-Phoenix model T eff = 2300 K log g = 5.5 (cgs) [M/H] = -1.0 " = 0.51 Near-infrared Normalized f! SDSS J 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) Wavelength (Angstroms)

34 Results: The Good Motivation Results 1.0 2MASS T = 2900 K Orbits & Atmospheres 0.8 [M/H] = -2.0 log g = 5.0 (cgs) Exemplary Cases Normalized F! " 2 = 6.06 DOF = Wavelength (µm) [M/H] Burgasser et al. (in prep) T eff (K) 0.010

35 Results: The Good Motivation Results 1.0 2MASS T = 2200 K Orbits & Atmospheres 0.8 [M/H] = -1.0 log g = 5.5 (cgs) Exemplary Cases Normalized F! " 2 = 141. DOF = Wavelength (µm) [M/H] Burgasser et al. (in prep) T eff (K)

36 0.001 Results: The Ugly Motivation Results 1.0 LSR T = 2900 K Orbits & Atmospheres 0.8 [M/H] = -0.5 log g = 5.0 (cgs) Exemplary Cases Normalized F! " 2 = 1035 DOF = Wavelength (µm) [M/H] Burgasser et al. (in prep) T eff (K)

37 Results: The Ugly Normalized F! LSR T = 3300 K [M/H] = -2.5 log g = 5.0 (cgs) " 2 = 4.88 DOF = 111 Motivation Results Orbits & Atmospheres Exemplary Cases Burgasser et al. (in prep) Wavelength (µm) [M/H] T eff (K)

38 Temperature v. Spectral Type d/sd sd esd usd Motivation Results Orbits & Atmospheres Exemplary Cases T eff (K) M6 M7 M8 M9 L0 L1 L2 L3 L4 L5 L6 L7 Spectral Type Burgasser et al. (in prep.)

39 Metallicity v. Metallicity Type Motivation Results [M/H] d/sd sd esd usd Orbits & Atmospheres Exemplary Cases ! Burgasser et al. (in prep.)

40 Eccentricity v. [M/H] Motivation Results Orbits & Atmospheres Exemplary Cases Eccentricity d/sd sd esd usd [M/H] Burgasser et al. (in prep.)

41 Inclination v. [M/H] Inclination (degrees) d/sd sd esd usd [M/H] Motivation Results Orbits & Atmospheres Exemplary Cases Burgasser et al. (in prep.)

42 Angular Momentum v. [M/H] L z (km 2 s -1 ) M d/sd sd esd usd Motivation Results Orbits & Atmospheres Exemplary Cases [M/H] Burgasser et al. (in prep.)

43 usdm8.5 2M : a Stream Star? Motivation Results Orbits & Atmospheres Exemplary Cases Anticenter Stream (Grillmair et al. 2008) Several streams are prograde, [Fe/H] and reside entirely within 50 pc of the Sun Is 2M a tracer of one? GD-1 Stream (Willett et al. 2009)

44 sd?m6pec LSR : Peculiar for Orbital Reasons? Motivation Results Orbits & Atmospheres Exemplary Cases Does an orbit plunging deep into the center of the Galaxy explain LSR s peculiarities? Dahn et al. (2008) also Lepine et al. (2003); Reiners & Basri (2006); Cushing et al. (2006)

45 Summary

46 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 and peculiar LSR

47 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

48 The FIRE Spectrograph Near-infrared Echellette for the Magellan Telescopes µm in a single image λ/δλ~6000 cross-dispersed (50 km/s; 0.6 slit) λ/δλ~ prismdispersed (high throughput) Commissioning January 2009 Simcoe, Burgasser, Schechter et al. (2008) Don t forget the swag!

49 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

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51 The Galactic Orbits of Ultracool Subdwarfs Adam J. Burgasser UC San Diego/MIT