The JCMT Legacy Survey of the Gould Belt : a first look at Taurus with HARP

Davis, C.J.; Chrysostomou, A.; Hatchell, J.; Wouterloot, J. G. A.; Buckle, J. V.; Nutter, D.; Fich, M.; Brunt, C.; Butner, H.; Cavanagh, B.; Curtis, E.I.; Duarte-Cabral, A.; Di Francesco, J.; Etxaluze, M.; Friberg, P.; Johnstone, D.; Matthews, B.; Matthews, H.; Rawlings, J.M.C.; Richer, J. S.; Roberts, J.; Sadavoy, S.; Simpson, R.J.; Tothill, N.F.H.; Tsamis, Y.G.; Viti, S.; Ward-Thompson, D.; White, G.J.; Yates, J.

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Author

Davis, C.J.

Chrysostomou, A.

Hatchell, J.

Wouterloot, J. G. A.

Buckle, J. V.

Nutter, D.

Fich, M.

Brunt, C.

Butner, H.

Cavanagh, B.

Curtis, E.I.

Duarte-Cabral, A.

Di Francesco, J.

Etxaluze, M.

Friberg, P.

Johnstone, D.

Matthews, B.

Matthews, H.

Rawlings, J.M.C.

Richer, J. S.

Roberts, J.

Sadavoy, S.

Simpson, R.J.

Tothill, N.F.H.

Tsamis, Y.G.

Viti, S.

Ward-Thompson, D.

White, G.J.

Yates, J.

Abstract

As part of a James Clerk Maxwell Telescope (JCMT) Legacy Survey of star formation in the Gould Belt, we present early science results for Taurus. CO J= 3 –2 maps have been secured along the north-west ridge and bowl, collectively known as L 1495, along with deep 13CO and C18O J= 3 –2 maps in two subregions. With these data, we search for molecular outflows, and use the distribution of flows, Herbig–Haro (HH) objects and shocked H2 line-emission features, together with the population of young stars, protostellar cores and starless condensations to map star formation across this extensive region. In total, 21 outflows are identified. It is clear that the bowl is more evolved than the ridge, harbouring a greater population of T Tauri stars and a more diffuse, more turbulent ambient medium. By comparison, the ridge contains a much younger, less widely distributed population of protostars which, in turn, is associated with a greater number of molecular outflows. We estimate the ratio of the numbers of pre-stellar to protostellar cores in L 1495 to be ∼1.3–2.3, and of gravitationally unbound starless cores to (gravitationally bound) pre-stellar cores to be ∼1. If we take previous estimates of the protostellar lifetime of ∼5 × 105 yr, this indicates a pre-stellar lifetime of 9(±3) × 105 yr. From the number of outflows, we also crudely estimate the star formation efficiency in L 1495, finding it to be compatible with a canonical value of 10–15 per cent. We note that molecular outflow-driving sources have redder near-infrared colours than their HH jet-driving counterparts. We also find that the smaller, denser cores are associated with the more massive outflows, as one might expect if mass build-up in the flow increases with the collapse and contraction of the protostellar envelope.