Modeling of the Vela complex including the Vela supernova remnant, the binary systemγ² Velorum, and the Gum nebula

Abstract

We study the geometry and dynamics of the Vela complex including the Vela supernova remnant (SNR), the binary system γ 2 Velorum and the Gum nebula. We show that the Vela SNR belongs to a subclass of non-Sedov adiabatic remnants in a cloudy interstellar medium (ISM), the dynamics of which is determined by the heating and evaporation of ISM clouds. We explain observable characteristics of the Vela SNR with a SN explosion with energy 1.4 × 10 50 erg near the step-like boundary of the ISM with low intercloud densities (∼10 −3 cm −3 ) and with a volume-averaged density of clouds evaporated by shock in the north-east (NE) part about four times higher than the one in the south-west (SW) part. The observed asymmetry between the NE and SW parts of the Vela SNR could be explained by the presence of a stellar wind bubble (SWB) blown by the nearest-to-the Earth Wolf-Rayet (WR) star in the γ 2 Velorum system. We show that the size and kinematics of γ 2 Velorum SWB agree with predictions of numerical calculations for the evolution of the SWB of M ini = 35 M star. The low initial mass of the WR star in γ 2 Velorum implies that the luminosity of the nuclear line of 26 Al, produced by γ 2 Velorum, is below the sensitivity of existing gamma-ray telescopes.

Modelling of the radio emission from the Vela supernova remnant

“…The distance and the age of the Vela SNR have been determined accurately enough to make it a perfect object for the investigation of physical processes. Several estimates of the distance to the remnant exist (see Sushch et al 2011, and references therein), the most reliable of which was determined from the VLBI parallax measurements of the Vela pulsar and is D Vela = 287 +19 −17 pc (Dodson et al 2003). Equatorial coordinates (J2000 epoch) of the Vela pulsar, which is assumed to be situated in the geometrical centre of the remnant, are α Vela = 08 h 35 m 20.66 s and δ Vela = −45 • 10 35.2 .…”

“…A shock velocity V sh of the middle-aged adiabatic SNR depends on the shock radius R sh and the age t age as V sh = 0.4R sh /t age . In the case of the Vela SNR, we know both R sh ∼ 20 pc (from the angular size and the distance to the Vela SNR) and V sh ∼ 660−1020 km s −1 (from the postshock temperature of 0.5-1.2 keV of the X-ray emitting gas) (Aschenbach et al 1995;Sushch et al 2011), which results in the hydrodynamical age of t age = (0.7−1.2) × 10 4 yr, which is close to the characteristic age.…”

“…The bulk of the X-ray emission is distributed all over the SNR without evidence of the main shock. Both features were recently explained in Sushch et al (2011) within the assumption that the Vela SNR progenitor supernova exploded on the border of the stellar wind bubble (SWB) of the nearby WolfRayet (WR) star in the binary system γ 2 Velorum and that the remnant expands in a highly inhomogeneous, cloudy, interstellar medium (ISM). Indeed, exploding at the border of the SWB, the remnant would expand into two media with different densities, A&A 561, A139 (2014) which in turn would cause a change of the X-ray luminosity and size from the NE part to the SW part of the remnant.…”

“…The hot evaporated gas component with the volume filling factor close to unity dominates the shock dynamics, while the cooler and denser component with the filling factor close to zero dominates the X-ray radiation from the remnant. The role of the initial intercloud ISM gas is negligible (Sushch et al 2011). …”

The molecular gas around the luminous blue variable star G24.73+0.69

“…These explosions usually occur when the progenitor star still lies close to its natal cloud and while other companion stars may still be in the MS or LBV/WR phase. As a consequence, several supernova remnants have been observed interacting with evolved massive stars (see Velázquez et al 2003;Sushch et al 2011) and molecular gas (see Jiang et al 2010, for an exhaustive list of SNR/MC associations).…”