Nova grains

A few silicon carbide and graphite grains appear to have come from novae (Chapter 3). 

These grains carry the signatures of explosive hydrogen burning, although the magnitudes 

20Ne/22 Ne ratios lower than predicted from models of AGB stars. Very low 20Ne/22Ne 

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Ernissee, J.J., and Abbott, W.H. (1975) Binding of mineral grains by a species of Thallassiosira. Nova. Hedwigia. Beth. 53, 241-252. 

Some 26A1 may also be produced by the classical nova explosions. In these the entire star does not explode rather, about 0.0001 solar masses of skin on a white dwarf experiences a thermonuclear runaway, some fraction of which is ejected in the nova outburst. This ejecta should contain live26 Al, especially from a subset of Mg-rich novae. Magnesium is the parent from which26 Al is created during the explosion. Dust grains that condense Al in the ejecta from the novae will carry excess 2 Mg from this initial content of26 Al, as Fred Hoyle and I pointed out in 1975-76. 

Laboratory studies of presolar dust grains also show that dust is formed in the mass ejected after an SN explosion, as will also be discussed in Section 2.2. Observations show that the ejected mass shells occasionally do form dust some time after the SN explosions (e.g. Bianchi Schneider 2007), but generally the efficiency of dust production seems to be rather low (Bianchi Schneider 2007 Zhukovska et al. 2008). Other important sources of stardust are red supergiants (mostly silicate dust). Most of the dust from red supergiants, however, is not expected to survive the shock wave from the subsequent SN explosion of the star (Zhukovska et al. 2008). Some dust is also formed by novae (Amari et al. 2001b), Wolf-Rayet stars (WRs, Crowther 2007), and luminous blue variables (LBVs, Voors et al. 2000), but the dust quantities formed by these are very small. Stardust - i.e. dust that is formed in stellar outflows or ejecta - in the interstellar medium is dominated by dust from AGB stars. 

Presolar grains exhibit large isotopic anomalies not only in their major elements, but also in many minor elements. Isotopic ratios vary over many orders of magnitude, indicative of contributions from different types of stellar sources, namely evolved stars, novae, and SN explosions. Isotope anomalies are also seen in objects with Solar System origin, which, however, are much smaller than those in presolar grains. For example, the calcium-aluminum-rich inclusions (CAIs), the earliest... 

Figure 2.6 Carbon- and nitrogen-isotopic compositions of presolar SiC grains. Predictions from stellar models are shown for comparison. Solar metallicity AGB star models Nollett et al. (2003), Type II SN Rauscher et al. (2002), novae Jose et al. (2004). For data sources see Lodders Amari (2005) Zinner (2007). Note that for the solar 14N/15N ratio the value inferred for Jupiter s atmosphere is shown.

A few grains have isotopic ratios that are best explained by a nova origin (Amari et al., 2001a). These grains have low and " N/ N ratios... 

Amari S., Gao X., Niftier E., Zinner E., Jose J., Hernanz M., and Eewis R. S. (2001a) Presolar grains from novae. 

Nichols R. H., Jr., Kehm K., Hohenberg C. M., Amari S., and Lewis R. S. (2003) Neon and helium in single interstellar Sic and graphite grains asymptotic giant branch, Woh-Rayet, supernova and nova sources. Geochim. Cosmochim. Acta (submitted). 

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