Glycolaldehyde in Perseus young solar analogs^⋆,⋆⋆

¹ INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
e-mail: codella@arcetri.astro.it
² ESO, Karl Schwarzchild Str. 2, 85748 Garching bei München, Germany
³ Excellence Cluster “Universe”, Boltzmannstr. 2, 85748 Garching bei München, Germany
⁴ Gothenburg Center for Advance Studies in Science and Technology, Department of Mathematical Sciences, Chalmers University of Technology and University of Gothenburg, 412 96 Gothenburg, Sweden
⁵ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
⁶ Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu – CNRS – Université Paris Diderot, CE Saclay, 91191 Gif-sur-Yvette Cedex, France
⁷ Université Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
⁸ CNRS, IPAG, 38000 Grenoble, France

Received: 12 November 2016
Accepted: 29 December 2016

Abstract

Context. The earliest evolutionary stages of low-mass protostars are characterised by the so-called hot-corino stage, when the newly born star heats the surrounding material and enrich the gas chemically. Studying this evolutionary phase of solar protostars may help understand the evolution of prebiotic complex molecules in the development of planetary systems.

Aims. In this paper we focus on the occurrence of glycolaldehyde (HCOCH₂OH) in young solar analogs by performing the first homogeneous and unbiased study of this molecule in the Class 0 protostars of the nearby Perseus star forming region.

Methods. We obtained sub-arcsec angular resolution maps at 1.3 mm and 1.4 mm of glycolaldehyde emission lines using the IRAM Plateau de Bure (PdB) interferometer in the framework of the CALYPSO IRAM large program.

Results. Glycolaldehyde has been detected towards 3 Class 0 and 1 Class I protostars out of the 13 continuum sources targeted in Perseus: NGC 1333-IRAS2A1, NGC 1333-IRAS4A2, NGC 1333-IRAS4B1, and SVS13-A. The NGC 1333 star forming region looks particularly glycolaldehyde rich, with a rate of occurrence up to 60%. The glycolaldehyde spatial distribution overlaps with the continuum one, tracing the inner 100 au around the protostar. A large number of lines (up to 18), with upper-level energies E_u from 37 K up to 375 K has been detected. We derived column densities ≥10¹⁵ cm^-2 and rotational temperatures T_rot between 115 K and 236 K, imaging for the first time hot-corinos around NGC 1333-IRAS4B1 and SVS13-A.

Conclusions. In multiple systems glycolaldehyde emission is detected only in one component. The case of the SVS13-A+B and IRAS4-A1+A2 systems support that the detection of glycolaldehyde (at least in the present Perseus sample) indicates older protostars (i.e. SVS13-A and IRAS4-A2), evolved enough to develop the hot-corino region (i.e. 100 K in the inner 100 au). However, only two systems do not allow us to firmly conclude whether the primary factor leading to the detection of glycolaldehyde emission is the environments hosting the protostars, evolution (e.g. low value of L_submm/L_int), or accretion luminosity (high L_int).