M. Shara, March 19, 2009 Ultra-Luminous Red Novae: Extreme CVs or Mergebursts? M. Shara and D. Zurek American Museum of Natural History Ofer Yaron Dina Prialnik Attay Kovetz Tel-Aviv University Howard Bond (under protest) Space Telescope Science Institute

M. Shara, March 19, 2009Overview A New Astrophysical Phenomenon? *M31-RV (Red Variable) *V838 Mon *Why these “can’t” be classical novae… New Nova models which mimic Red novae…prediction *Probable recovery of M31-RV *Is V838 Mon really in a cluster? ==>Occum is as sharp as ever

M. Shara, March 19, 2009 The Current Party line: “Luminous Red Novae are A New Astrophysical Phenomenon” *M31-Red Var, V4332 Sgr and V838 Mon could be all manifestations of a new class of astronomical objects *"Based on such comparisons, there is a fair possibility that all three objects belong to a new class of astronomical objects *In our opinion V838 Mon and V4332 Sgr are manifestations of a new class of eruptive variables *Our main goal is to point out that the energy source of the outburst of V838 Mon was, and still is, an accretion event, i.e., gravitational energy, rather than thermonuclear runaway *The spectral evolution and mainly the absence of any nebular phase excludes the simplest scenario of classical nova *V838 Mon's rapid transformation from a faint G or F star to a bright "later-than-M-class" star in a few months may represent a previously unobserved stage in stellar evolution, or perhaps a new kind of star altogether

M. Shara, March 19, 2009 M31-RV (Red Variable) of 1988 Mbol ~ -9.5 to -9.9 = 4-7 x 10 5 Lsun

M. Shara, March 19, 2009 M31 RV was RED

M. Shara, March 19, 2009 V838 Mon light-echo => 6 kpc distance => Lmax ~ 5x10 5 Lsun GAP

M. Shara, March 19, 2009 V838 Mon is VERY Red and Oxygen-Rich

M. Shara, March 19, 2009 CLAIMS: 1) CLASSICAL NOVAE AREN’T RED 2) CNe show coronal emission i.e. CNe CAN’T EJECT Msun ENVELOPES 3)Classical novae can’t reach M= -10 4) Classical novae don’t show 3 or 4 peaks in brightness 5) V838 Mon is in a “cluster” with 4 B stars…it must be very young RESPONSES: 1+2)M WD = 0.5 Msun, mdot= few x Msun/yr => 2x10 -3 Msun ENVELOPE which becomes HUGE, COOL, RED 3) Nova models making M = -9 is easy. A cold envelope with low opacity (kappa 2x10 -3 Msun ENVELOPE which becomes HUGE, COOL, RED 3) Nova models making M = -9 is easy. A cold envelope with low opacity (kappa <0.4) easily gives M= -13 4) Nova models mimic V838 Mon and M31 RV with multiple peaks 5) V838 Mon not associated with the line-of-sight B3 star OCCUM’s RAZOR : Red Novae are TNR-powered Classical novae

M. Shara, March 19, 2009 A Poorly Explored Corner of Classical Nova Phase Space: WD =0.5 Msun, mdot = 7x Msun/yr,Twd = 2x10 6 o K => Very slow, very red, very luminous nova Menvelope (ejected by TNR) = 1.4x10 -3 Msun 6 nuclear flashes Envelope Expansion 1 Year!

M. Shara, March 19, 2009 Model’s Light Curve and Temperature Match Key Observables COLD; <2,000 o K Lmax> 3x10 5 Lsun Pre-Max Rise 3-4 luminosity peaks

M. Shara, March 19, O : 14 N : 12 C Model 5.7 : 4.7 : 1.0 OXYGEN RICH Solar 2.1 : 0.25 : O : 14 N : 12 C Model 5.7 : 4.7 : 1.0 OXYGEN RICH Solar 2.1 : 0.25 : 1.0

M. Shara, March 19, 2009 A !TESTABLE! PREDICTION for the next Ultra-Luminous Red Nova 1 Year Plateau at L=1000 Lsun… No data for V838 Or M31 RV

M. Shara, March 19, 2009 The Field of M31-RV in M31(F435W)

M. Shara, March 19, 2009 HST F300W - Candidate candidate

M. Shara, March 19, 2009 UV-bright candidate in 1994 Gone in 2008! (>8x fainter) m(300)=21.4m(300)>23.7

M. Shara, March 19, 2009 Fading in 5 years in F435W (60% fainter) m(435)=24.1 m(435)=24.6

M. Shara, March 19, 2009 Constant in F555W over 9 years m(555)=23.7 m(555)=23.5

M. Shara, March 19, 2009 Constant in F814W over 9 years V-I = 0.3 m(814)=23.3 m(814)=23.2

M. Shara, March 19, 2009 V838 Mon and Comparison Star with HST/ACS v838 comp 0.1”

M. Shara, March 19, 2009 [FeII] in v838 spectrum-Kaminski poster Claim: It’s photoionization due to the B3V companion Counterclaim: Successive shell ejection at slightly different velocities=> collisions and weak shocks

M. Shara, March 19, 2009 Summary Summary *Very low WD mass + Very cold WD +Very low accretion rate  TNR in Massive WD envelopes (~10 -3 Msun), low ejection velocities, multiple light peaks and shells, oxygen-rich, weak shocks and ==> Lmax~10 6 Lsun *Good match to v838 Mon…hot remnant SOON! *HST- Recovered remnant at site of M31-RV is fading like a nova, NOT like a mergeburst TESTABLE PREDICTION for future Red Novae: There is a rise to L~1000 Lsun for ~1 year before “main eruption” to L ~ 10 6 Lsun