Proposal Details - 0720007
26Al from the Closest Massive Stars: Sco-Cen (Diehl)

Proposal Abstract

We aim to measure radioactivity from massive stars in the immediate solar vicinity, supporting studies of the nearby supernova and massive-star activity. 26Al is a tracer of supernovae and winds from very massive stars, and complements observations of massive-star remnants such as supernova shells and pulsars. Indications of past supernova activity originating in the Sco-Cen association at distances of ~150 pc have been derived from the Local Bubble surrounding the Sun, from nearby loop structures such as Loop I, and also from 60Fe deposits in oceancrust material. COMPTELs all-sky measurement of 26Al gamma-rays indicated emission from the suspected region holding stars of ~5 Myr age (Upper Sco), and now a signal of 26Al from this region is also indicated from SPI data. We aim to exploit this unique opportunity and measure the intensity and kinematics of this nearby interstellar 26Al decay with INTEGRAL, through a special multi-year observing program of sufficient depth and minimizations of systematic effects. These observations also will support studies of other diffuse emissions and of source populations in the inner ridge of the Galaxy.

Observation Strategy (Recommended by TAC)

1 Ms in the standard 5x5 dithering mode centred on RA, Dec = 243.94, -26.169 (l, b = 350, 17.5).

Proposal grade: C

Data Rights (Recommended by TAC)

The TAC has allocated the following specific data rights to this proposal: line emission from 26Al (1.809 MeV), 60Fe (1.173 and 1.332 MeV), and positron/electron annihilation line (511 keV) as well as ortho- positronium continuum emission.

Exposure Map

The exposure maps are in galactic coordinates and units of ksec, and the colour scale is indicated at the bottom. The green lines provide the 100 ksec contour.