Large‐Area Mapping at 850 Microns. II. Analysis of the Clump Distribution in the ρ Ophiuchi Molecular Cloud

Origin of the prestellar core mass function and link to the IMF – Herschel first results

“…While the early determination of the CMF by Motte et al (1998), based on only 57 prestellar condensations, was clearly limited by small-number statistics, similar results were consistently found by a number of independent groups in the past decade and the statistics improved somewhat over the years (e.g. Testi & Sargent 1998;Johnstone et al 2000Johnstone et al , 2001Motte et al 2001;Stanke et al Motte et al 2001, Johnstone et al 2001, and Nutter & Ward-Thompson 2007. A two-segment power-law fit and a log-normal fit are shown for comparison.…”

“…In particular, this has led to concerns that the shape of the CMF may be strongly affected by incompleteness effects at the low-mass end (e.g. Johnstone et al 2000). Third, there are hints that the star formation efficiency at the level of an individual core ( core ), corresponding to a global shift in mass scale between the CMF and the IMF, may vary from cloud to cloud, with values ranging from core ∼ 15% in Taurus (Onishi et al 2002), to core ∼ 30% in the Pipe (Alves et al 2007), to core ∼ 50-100% in Ophiuchus (Motte et al 1998).…”

Submillimetre Studies of Prestellar and Starless Cores in the Ophiuchus, Taurus and Cepheus Molecular Clouds

“…There have been many previous wide-field millimetre and submillimetre studies of the starless core population in the L1688 cloud (e.g. Motte et al 1998, hereafter MAN98;Johnstone et al 2000;Enoch et al 2008;Simpson et al 2008, hereafter S08;Simpson et al 2011). 3.1 Observations…”

“…The distribution of prestellar core masses is known as the Core Mass Function (CMF). An IMF-like CMF -a powerlaw distribution at high masses, with a turnover at low masses -has been found in all nearby star-forming molecular clouds for which a CMF has been observed, including Ophiuchus (Motte et al 1998;Johnstone et al 2000;Enoch et al 2007),…”

“…However, the external pressure is often a dominant term in the energy balance of starless cores (e.g. Johnstone et al 2000;Maruta et al 2010), and so it is necessary to parameterise this effect, typically in the manner described herein.…”