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Source to Negative Superhumps. Michele M. Montgomery, UCF MNRAS, 2009, accepted 1/16. “Never do a calculation until you already know the answer.” J.A. Wheeler’s First Moral Principle. Wild Stars in the Old West II March 19, 2009. What are Negative Superhumps (and why should you care)?.

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Source to negative superhumps
Source to Negative Superhumps

Michele M. Montgomery, UCF MNRAS, 2009, accepted 1/16

“Never do a calculation until you already know the answer.” J.A. Wheeler’s First Moral Principle

Wild Stars in the Old West II

March 19, 2009


What are negative superhumps and why should you care
What are Negative Superhumps (and why should you care)?

AM CVn

Pneg=1011 s

Porb=1028 s

Ppos=1058 s

V603Aql

Pneg=0.134 d

Porb=0.1382 d

Ppos=0.146 d

Harvey et al., 1998, ApJ, 493, L105

Patterson et al. 1997


What are negative superhumps and why should you care1
What are Negative Superhumps (and why should you care)?

AM CVn

Pneg=1011 s

Porb=1028 s

Ppos=1058 s

V603Aql

Pneg=0.134 d

Porb=0.1382 d

Ppos=0.146 d

CBA

Harvey et al., 1998, ApJ, 493, L105

Patterson et al. 1997


What are negative superhumps and why should you care2
What are Negative Superhumps (and why should you care)?

CBA

AM CVn

Pneg=1011 s

Porb=1028 s

Ppos=1058 s

V603Aql

Pneg=0.134 d

Porb=0.1382 d

Ppos=0.146 d

CBA

Harvey et al., 1998, ApJ, 493, L105

Patterson et al. 1997


What are negative superhumps and why should you care3
What are Negative Superhumps (and why should you care)?

CBA

AM CVn

Pneg=1011 s

Porb=1028 s

Ppos=1058 s

V603Aql

Pneg=0.134 d

Porb=0.1382 d

Ppos=0.146 d

CBA

Harvey et al., 1998, ApJ, 493, L105

CBA

Patterson et al. 1997


Which systems show negative superhumps
Which Systems Show Negative Superhumps?

Montgomery (2009), Osaki (1985)

CV Tree Census


How do you generate negative superhumps
How Do You Generate Negative Superhumps?

  • Partial or Fully Tilted disk (Patterson et al. 1993, Wood, Montgomery, & Simpson, 2000; Montgomery 2004; Montgomery 2009)

  • Warped Accretion Disk (Petterson 1977, Murray & Armitage 1998, Terquem & Papaloizou 2000, Murray et al. 2002, Foulkes, Haswell, & Murray 2006)

  • Tidally Induced Warp (Bisikalo et al. 2004)

Montgomery (2004)

Foulkes, Haswell, & Murray (2006)


Suggested sources to negative superhumps
Suggested Sources To Negative Superhumps

  • Gravitational E as gas flows over edge to inner disk (Patterson et al. 1997)

  • Varying EK of gas stream as it impacts one face of disk through locus of points as secondary orbits CoM (Barrett et al. 1988)

  • Tidal field disturbing fluid flow in each of two disk halves (Wood, Montgomery, Simpson 2000)

  • Whole disk inclined out of orbital plane, gas stream flowing over or under edge of disk (Foulkes et al. 2006)

  • Bright spot transiting across face of disk as secondary orbits CoM (Wood & Burke 2007)

Foulkes, Haswell, & Murray (2006)


Does the bright spot transit disk face
Does the Bright Spot Transit Disk Face?

Montgomery (2009)

SPH Code

  • 100,000 particles

  • 0.35 ≤ q ≤ 0.55, M1=0.8M

  • ~10-10 M yr -1

  • P=(-1)u, =1.01

  • ,=0.5 (’=0.05)

  • M2-Porb (Smith & Dhillon 1998)

  • 2,3,4O Tilt at orbit 200

Murray & Armitage (1998)


Clues to source of negative superhumps
Clues to Source of Negative Superhumps

  • Degree of Disk Tilt (Montgomery 2009)

  • Mass Transfer Rate (Wood & Burke 2007)

  • Mass Ratio (Montgomery 2009)


Location in disk that powers the negative superhump
Location in Disk that Powers the Negative Superhump

Orbit 220

Frame 150 (min) Frame 220 (max)

Orbit 215

Frame 0 (min) Frame 0 (max)

Montgomery (2009)

AAS #214 - UCF UG Mark Guasch


Summary montgomery 2009
Summary(Montgomery 2009)

  • >3O disk tilt (agrees with Murray et al. 1998)

  • q, mass transfer rate, degree of tilt affect negative superhump signal strength

  • No harmonics in light curves of low mass transfer rate systems

  • Location in disk of negative superhump is innermost annuli

  • Source is innermost annuli emission that waxes and wanes with gas flow as secondary orbits CoM. Gas streams transitions from flowing over to under (and vice versa) at disk nodes twice per orbit.

  • For other conclusions, see Montgomery (2009)

    montgomery_at_physics.ucf.edu


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