source to negative superhumps

Source to Negative Superhumps

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

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QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture. Wild Stars in the Old West II

March 19, 2009

“Never do a calculation until you already know the

answer.” J.A. Wheeler’s First Moral Principle

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



Patterson et al. 1997

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


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




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



CBA




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



CBA



CBA



Which Systems Show Negative Superhumps?

CV Tree Census

Montgomery (2009), Osaki (1985)

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

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?

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

Montgomery (2009)

Murray & Armitage

(1998)

Clues to Source of Negative Superhumps

1. Degree of Disk Tilt (Montgomery 2009)

2. Mass Transfer Rate (Wood & Burke 2007)

3. Mass Ratio (Montgomery 2009)

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)

1. >3O disk tilt (agrees with Murray et al. 1998)

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

3. No harmonics in light curves of low mass transfer rate systems

4. Location in disk of negative superhump is innermost annuli

5. 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.

6. For other conclusions, see Montgomery (2009)

montgomery_at_physics.ucf.edu

source to negative superhumps

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