Multiple Protostellar Systems (MPSs) are common at every evolutionary
stage, and yet their formation and evolution are still little understood. Models and
simulations predict that MPSs most likely form through fragmentation, but the ques-
tions of when and how are still left widely open. Continuum surveys of MPSs have
been performed at every evolutionary stage, but the results can only address the mul-
tiplicity distribution. To fully understand and constrain the formation and evolution
mechanisms of MPSs, the multiplicity, coevality, outflow and circumstellar environ-
ment must be addressed. MPSs present many chanllenges, as they can be deeply en-
tangled through dynamical evolution and internal interaction. Disentangling MPSs,
however, can prove to be rewarding, revealing not only insight into the system but
providing a true star formation laboratory. To achieve this goal, a thorough look
into a MPS is needed. In this work, we present one such thorough investigation into
the much debated protostellar system VLA1623, located in ρ Ophiuchi (L1688) at
a distance of 120pc. Here millimeter, submillimeter and infrared observations and
archival data along with data from literature are used to present an almost complete
picture VLA1623. The results and analysis presented in this work provide surprising
and interesting insight into this system, revealing VLA1623 to be a triple non-coeval
protostellar system, with each source driving its own outflow and two sources driving
jets as well as unevenly distributed circumstellar material. Finally, one component,
VLA1623B, is found to be an extremely young protostellar source with characteristics
between a starless core and a Class 0 object.

Abstract ii
Acknowledgements iii
List of Figures viii
List of Tables ix
1 Introduction 1
1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 VLA1623 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 Data . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1 Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1.1 SMA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1.2 ALMA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2 Archival Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.3 Collaborations and other data 9
3 Results . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1 Continuum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2 Outflows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.3 Circumstellar environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.3.1 SO (9-8) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.3.2 C17 O (3-2) & C18 O (2-1) . . . . . . . . . . . . . . . . . . . . . . . . 15
3.4 ALMA Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.4.1 12 CO (2-1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.4.2 C18 O (2-1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.4.3 DCO+ (3-2) . . . . . . . . 19
4 Analysis 23
4.1 Spectral Energy Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.2 Physical Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.2.1 Bolometric and Submillimeter Luminosities (Lbol & Lsubmm ) . . . . . 26
4.2.2 Envelope Mass (Menv ) . . . . . . . . . . . . . . . . . . . . . 26
4.2.3 Column and Number Densitites (NH2 & nH2 ) . . . . . . . . 27
4.2.4 On undersampled SEDs, luminosities and Error in derived physical
parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
4.3 Outflows and Jets . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
4.3.1 12 CO outflows . . . . . . . . . . . . . . . . . . . . . . . . . 28
4.3.2 Jets in H2 and IRAC 2 . . . . . . . . . . . . . . . . . . . . 29
4.4 Circumstellar Envelope . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.4.1 SO (9-8) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.4.2 C17 O (3-2) & C18 O (2-1) . . . . . . . . . . . . . . . . . . . 35
4.4.3 DCO+ (3-2) . . . . . . . . . . . . . . . . . . . . . . . . . . 38
5 Discussion 42
5.1 VLA1623W . . . . . . . . . . . . 42
5.2 VLA1623A . . . . . . . . . . . . 44
5.3 VLA1623B . . . . . . . . . . . . 45
5.4 A model for VLA1623’s outflows . . . . . . . . . . . . 46
5.5 Formation Scenario . . . . . . . . 46
6 Conclusions 49
Bibliography 50
A Equations and Methods to derive Physical Parameters 55
A.1 Total Mass Mtot . . . . . . . . . . . . . . . . . . . . . . . . 55
A.2 Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
A.2.1 Column Density NH2 . . . . . . . . . . . . . . . . . 55
A.2.2 Number Density nH2 . . . . . . . . . . . . . . . . . 56
A.3 Luminosity . . . . . . . . . . . . . . . . . . . . . . . . . . 56
A.3.1 Bolometric and Submillimeter Luminosity . . . . . . . . . . 56

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