Intro
Supervisor's Foreword
Preface
Acknowledgements
Contents
1 Introduction
1.1 Formation of Low-Mass (Solar-Type) Stars
1.2 Radio Astronomy
1.3 Astrochemistry in Star-Forming Region
1.3.1 1980s: Astrochemistry in High- and Low-Mass Star-Forming Region
1.3.2 1990s: Chemical Composition at a 103 au Scale
1.3.3 2000s: Chemical Diversity at a 102-103 au Scale
1.3.4 2010s: ALMA Era at 10-102 au Scale
1.4 Motivation for This Research
1.5 Outline of This Thesis
References
2 ALMA Observation
2.1 Principles of Interferometers

2.1.1 Coordinate System
2.1.2 Correlation Function and Cross Power Spectrum
2.1.3 Visibility
2.2 ALMA
2.2.1 ALMA Site
2.2.2 Antennas
2.2.3 Receivers
2.2.4 Backends
2.3 Observations with Interferometers
2.3.1 Calibration
2.3.2 Observed Intensity Distribution
2.3.3 CLEAN Method
References
3 Model Calculation
3.1 Introduction
3.2 Infalling-Rotating Envelope Model
3.2.1 Configuration of the Infalling-Rotating Envelope Model
3.2.2 Infalling-Rotating Envelope Model with Various Physical Parameters
3.3 Keplerian Model
3.4 Outflow Model

3.5 Physical Parameters of the Models
3.6 Examples of the Model Analysis
3.6.1 The L1527 Case
3.6.2 The TMC-1A Case
3.6.3 Some Caveats for the Model
References
4 L1527
4.1 Introduction
4.2 Results
4.2.1 Overall Distribution
4.2.2 Envelope
4.2.3 Outflow
4.3 Discussion
4.3.1 Direction of the Outflow
4.3.2 Angular Momentum
References
5 IRAS 15398-3359
5.1 Introduction
5.2 Observations
5.3 Results
5.3.1 Overall Distribution of H2CO and CCH
5.3.2 Outflow
5.3.3 Protostellar Envelope
5.3.4 Comparison with an Envelope Model

5.4 Discussion
References
6 IRAS 16293-2422 Source A
6.1 Introduction
6.2 Observation Data
6.3 Molecular Line Distribution
6.4 Velocity Structure
6.4.1 OCS
6.4.2 CH3OH and HCOOCH3
6.4.3 H2CS
6.5 Infalling-Rotating Envelope Model
6.5.1 OCS
6.5.2 CH3OH and HCOOCH3
6.5.3 H2CS
6.6 Discussion
6.6.1 Infalling-Rotating Envelope and Its Centrifugal Barrier
6.6.2 Origin of the Chemical Change Around the Centrifugal Barrier
6.6.3 Gas Kinetic Temperatures of H2CS
6.6.4 Abundance of HCOOCH3 Relative to CH3OH
6.7 Summary of This Chapter
References

7 IRAS 16293-2422 Source B
7.1 Introduction
7.2 Observation
7.3 Distribution
7.4 Kinematic Structure
7.4.1 Observed Features
7.4.2 Comparison of Molecular Distribution with the Source A Case
7.5 Modelling
7.5.1 Infalling-Rotating Envelope Model
7.5.2 Origin of the Inverse P-Cygni Profile
7.6 Outflow
7.7 Gas Kinetic Temperature
7.8 Abundance of Metafont Relative to CH3OH
7.9 Summary of This Chapter
References
8 L483
8.1 Introduction
8.2 Observation
8.3 Distribution
8.4 Kinematic Structure
8.4.1 Geometrical Configuration
8.4.2 CS