•A •• No. 11 - November 1991 Low Mass Star Formation in Southern Molecular Clouds Edited by Ba Reipurth Published by EUROPEAN SOUTHERN OBSERVATORY Karl-Schwarzschild-Straße 2, D-8046 Garching bei München Germany © Copyright ESO 1992 Low Mass Star Formation in Southern Molecular Clouds Edited by Bo Reipurth ESO Scientific Report No. 11 November 1991 Table of Contents Low Mass Star Formation in Orion 1 J. Brand and J.G.A. Wouterloot The Canis Majoris OBl Association 59 G.lT. IIerbig Low Mass Star Formation in Puppis and Vela 69 B. Pcttcrsson The Chamaeleon Dark Clouds and T-Associations 93 R.D. Schu'artz The Southern Coalsack - Where are a11 the Young Stars? 119 L.-A Nyman The Star Forming Region in Lupus 127 J. Kraulter Young Low Mass Stars in the Norma Cloud 149 B. Reipurth and J.A. Graham Star Formation in the Ophiuchus Molecular Cloud Complex 159 B.A. lVilking Star Formation in the Corona Australis Region 185 J.A. Graham The Serpens Molecular Cloud 197 C. Eiroa iii Foreword and Acknowledgements In July 1989 an ESO Workshop on "Low Mass Star 'Formation and Pre-Main Sequence Objects" was held in Garehing near Munieh, Germany. The papers presented were published as ESO Conference and Workshop Proceedings No. 33. As part of the scientific activities of the workshop, a special poster session was held in which all the major southern star forming regions were described one by one by researchers with extensive experience in each. The purpose of this mini poster session was to attract attention to the richness of the southern star forming regions. Foul' out of five of the nearest star forming cloud complexes are in the southern sky, and yet, for geographical reasons, most of the observational work on the formation of stars has been performed in the northern sky. With the growth in the number of large southern opticaljinfrared telescopes and in the sophistication of their instrumentation, and the advent of southern radio telescopes like the Swedish-ESO-Sub-Millimeter Telescope and the Australia Tele­ scope, the situation is fortunately improving. The poster session was weIl received, and it was decided to compile the information in the form of a small book, thus disseminating it to a larger audience. The present book is the result of the efforts, of the ten colleagues whose collaboration I asked for, and I would like to express to them my sincere thanks for the care and dedication they have put into this project.. The book gives an overview of each of the most important southern regions of low mass star formation, and lists extensive references to the literature, with the aim to facilitate and encourage observers to obtain new data and add to our growing understanding of th'ese regions and o'f the star formation processes in general. While the authors and the editor have gone to great pains to ensure that all important papers up to about mid-1991 are mentioned, the sheer vastness of the literature makes it unavoidable that we have missed some papers. Readers are welcome to send their comments, corrections 01' additions to either the editor 01' the individual authors. If we after some years feel that the book has had a useful impact, it is a possibility that we may prepare a later version, updated with the hopefully large amounts of studies which are going to be performed in these southern star forming clouds. I am grateful to ESO for publishing this work, and to my colleagues who in various ways helped the project, in particular to Doris Leiva, who typed all the manuscripts. Bo Reipurth v Low Mass Star Formation in Orion J. Brandl and J.G.A. Wouterloot2 1 Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 1-50125 Firenze, Italy 2 I. Physikalisches Institut, Universität Köln, Zülpicker Str. 77, D-5000 Köln 41, Germany Introduction This contribution presents an ovcrview of low-mass (i.c. less than several1\18 ) star formation in Orion, its accompanying phenomena, and the moleculaI' environment in which it takes place. We tried 1.0 collect from the literature all relevant material, and to present it such thaI. it can be used by observers to find their way around in this arnazingly rieh and very thoroughly studied complex. We have restricted ourselves 1.0 the region betwecn a=Sh2'lm al\(l a=5hSGm, 8=-11° and 8=+4° (1950.0). In this area are located the large moleclliar cornplcxes consisting of LlGlO, L1641, L1647, and L1617, L1627, 1.1630 (LI-G2); see figurc 1 (tah'n frolll Klltn('r d (11., K3-77). Our literature search encompasses more than 130 ycars of ohservational work on Orion. From this, lists were compiled of Ha emission line stars (including T Tauri and I1erhig Ae/Be stars), reOection nebulae, JIerbig-IIaro (1111) ohjects, moleclliar out.f1ow-, IR-, and X­ ray sources, H20 masers, and the moleclliar c1011ds in which all these ohjeds are clnbcdded. Papers concerning observations of the above rncnt.ioned type of ohjects an~ includcd in our search; those thaI. are directly rclated 1.0 observations of the ionized gas, or the exeiting stars of the prominent IllI regions NGC1976/1977 (Ori A) and NGC2024 (Ori B), 01' 1.0 thc densc moleculaI' cloud OMC1, are not. For these, sec e.g. Goudis (Gl-82) or Cenzd all< I St.ut.zki (G4-89). In the following, thc information colleetcd from thc literature is prescnted in the form of tables, giving a.o. object identifications, coordinates, and a list of rd<'rcnecs in which thesc objeets are discussed. The rcferences are eoded; note thaI. referenccs 1.0 papers publishcd before 1900 are marked with an asterisk. Duc 1.0 the sheer vastness of thc material, no attempt has been made 1.0 either provide a historical context 01' to discuss th(~ data collected here in the sense of reviewing and combining thc variolls parts. The literature seareh was carried out by going through all thc AstronolllY and Astrophysics Abstracts books (1969-1 up to and incillding 1990-1); for the major jourJIal~ (AA, Ap.J, AJ, MNRAS) the literature is cornpldc up 1.0 DeccrnlH'r 1WW. 1"01' t.!l(' I><'riod I><,fore 1!)()!), thc volurncs of the Astronomischer .Jahresbericht werc consulte<l. Very 01<1 refcrences were seleeted from cross-references in the papers themselves, and from Müller and Hartwig (Ml­ 18), and Schneller (SI-52, SI-57, and SI-61). An extensive list of literature on variable stars has been prepared by lIuth and Wenzel (Hl-S1). A large number of papers are on phenomena associated with low-mass star formation in Orion in general, rather than about any specific objeet. Some of these are broad reviews, others discuss general aspects of IIH-objects, young stellar objeets, outflows etc., using the Orion region objeets as examples. These references are included in our list, but will not always be found in any of the tables. Because these papers are useful, they are mentioned in the text, at the appropriate locations. With reference to the tables, it is important to realize that not all parts of the region under consideration have been equally thoroughly studied. Most surveys of Ha emission line stars and variable stars, for instance, have concentrated on an area of a size of several square dcgrces centered on the Trapezium cluster, and not all were carried out to the same limiting magnitude. Likewise, surveys of NIR sources have been limited to small areas near some of the reflcction nebulac, to IRAS sources in L1641, and to parts of L1630. Attempts at an unbiascd search for I1crbig-Haro objeets are hampered by the strong optical emission of more cxtcndcd objeets in the region. This means that a statistical study, based on the material gathered here, of the relative frequency of the various types of objeets is not a straightforward matter. With regards to the emission line stars, this situation is now improving, with the publication of the large-scale systematic survey being carried out at Kiso Observatory by Wiramihardja and collaborators (K2-S9, W2-89, WI-91). The area immediately around the Trapczium cluster remains a problem, however: because of the large number of stars, and the intensc ncbulosity, distinguishing individual emission line stars is impossible in this type (objective prisrn) of survey (see also the rcmarks at the end of seetion 1). 1. Ha Emission Line Stars A distillet dass of low-mass pre-main sequence stars are the T Tau irregular variables. Apart from variability, Olle of their characteristics is lIa emission. In fact, searches for T Tau stars are mainly carried out by means of I1a objeetive prism surveys. If a star with Ha emission is found in a hcavily obscurcd area (such as the Lynds clouds in Orion) it is almost certainly aT Tau star 01' a rclatcd objeet (Ilerbig, 1I2-(2). The stars found in this way still have to be studied spcetroscopically, in order to rule out thc possibility of dMe 01' Be stars, supergiants, 01' symbiotic stars. This has to be kept in mind when using Table 1, which lists all Ha emission line stars in Orion, found in tltc literature (unlcss we found proof of their definite llOn-T Tauri naülre). Tlte prcscncc of Call emission, fluorescent FeI emission lines (at 4063, 4132 A), anel strong LiI absorption will conllrm thc T Tau nature (112-62). Surveys of HO' emission linc stars have in most cascs concentrated on the Trapezium region (in NGC1976 in L16'10), and the region anHlnd thc I10rsehead Nebula (in IC434 in LI630).