TY - JOUR

T1 - Search for 7Be in the outbursts of four recent novae

AU - Molaro, P.

AU - Izzo, L.

AU - Bonifacio, P.

AU - Hernanz, M.

AU - Selvelli, P.

AU - della Valle, M.

PY - 2020/3

Y1 - 2020/3

N2 - Following the recent detection of Be-7 II in the outburst spectra of classical novae, we report the search for this isotope in the outbursts of four recent bright novae by means of high-resolution Ultraviolet and Visual Echelle Spectrograph (UVES) observations. The Be-7 II lambda lambda 313.0583,313.1228 nm doublet resonance lines are detected in the high-velocity components of Nova Mus 2018 and ASASSN-18fv during outbursts. However, 7Be?II is not detected in ASASSN-17hx and possibly not in Nova Cir 2018, which shows that 7Be is not always ejected in the thermonuclear runaway. Taking into account the Be-7 decay, we find X(Be-7)/X(H) approximate to 1.5 x 10(-5) and 2.2 x 10(-5) in Nova Mus 2018 and ASASSN-18fv, respectively. A value of 7Be/H approximate to 2 x 10(-5) is found in five out of the seven extant measurements, and it can be considered as a typical 7Be yield for novae. However, this value is almost one order of magnitude larger than predicted by current theoretical models. We argue that the variety of high Be-7/H abundances could be the result of a higher than solar content of 3He in the donor star. The cases with Be-7 not detected might be related to the small mass of the white dwarf (WD) or to relatively little mixing with the core material of the WD. The Be-7/H, or Li-7/H, abundance is approximate to 4 dex above meteoritic abundance, thus confirming the novae as the main sources of Li-7 in the Milky Way.

AB - Following the recent detection of Be-7 II in the outburst spectra of classical novae, we report the search for this isotope in the outbursts of four recent bright novae by means of high-resolution Ultraviolet and Visual Echelle Spectrograph (UVES) observations. The Be-7 II lambda lambda 313.0583,313.1228 nm doublet resonance lines are detected in the high-velocity components of Nova Mus 2018 and ASASSN-18fv during outbursts. However, 7Be?II is not detected in ASASSN-17hx and possibly not in Nova Cir 2018, which shows that 7Be is not always ejected in the thermonuclear runaway. Taking into account the Be-7 decay, we find X(Be-7)/X(H) approximate to 1.5 x 10(-5) and 2.2 x 10(-5) in Nova Mus 2018 and ASASSN-18fv, respectively. A value of 7Be/H approximate to 2 x 10(-5) is found in five out of the seven extant measurements, and it can be considered as a typical 7Be yield for novae. However, this value is almost one order of magnitude larger than predicted by current theoretical models. We argue that the variety of high Be-7/H abundances could be the result of a higher than solar content of 3He in the donor star. The cases with Be-7 not detected might be related to the small mass of the white dwarf (WD) or to relatively little mixing with the core material of the WD. The Be-7/H, or Li-7/H, abundance is approximate to 4 dex above meteoritic abundance, thus confirming the novae as the main sources of Li-7 in the Milky Way.

KW - nuclear reactions, nucleosynthesis, abundances

KW - stars: individual: ASASSN-17hx

KW - stars: individual: Nova Mus 2018

KW - stars: individual: Nova Cir 2018

KW - stars: individual: ASASSN-18fv

KW - novae

KW - Galaxy: evolution

KW - EXPLOSIVE THERMONUCLEAR FORMATION

KW - GALACTIC EVOLUTION

KW - STELLAR EVOLUTION

KW - CLASSICAL NOVAE

KW - LI-7

KW - HE-3

KW - EMISSION

KW - NUCLEOSYNTHESIS

KW - CATALOG

KW - LITHIUM

U2 - 10.1093/mnras/stz3587

DO - 10.1093/mnras/stz3587

M3 - Journal article

VL - 492

SP - 4975

EP - 4985

JO - Royal Astronomical Society. Monthly Notices

JF - Royal Astronomical Society. Monthly Notices

SN - 0035-8711

IS - 4

ER -