10:45 AM - 11:05 AM
[MIS06-06] Astronomical Observations at Radio Wavelengths Exploring the Origin of Bio-related Molecules
★Invited Papers
Keywords:Interstellar molecules, Protostars, Protoplanetary disks, Radio astronomy
Interdisciplinary efforts among various approaches are required to explore the origin of life. The issues to be addressed by astronomical observations are : (i) what level of complex materials (or molecules) can form in the interstellar medium, and (ii) how these materials are brought into a protoplanetary disk, which is the site of planet formation. Recent progress in study of interstellar gas chemistry has provided us with important informations relevant to these issues in two directions.
One of them is high resolution imaging of a protoplanetary disk at millimeter/submillimeter wavelengths by ALMA. A protoplanetary disk as well as the central star gain their masses in the protostellar stage at which the disk-star system is deeply embedded within the circumstellar envelope. High resolution observations with ALMA revealed that chemical composition of gas was altered at the accretion shocks of disk outer edge, showing the importance of studying gas compositions at small scales. It has been unraveled by dust continuum imaging at high-angular resolution that ring-like structure is ubiquitous in the disks around T Tauri stars, and these rings are believed to be high-pressure regions (so called "pressure bumps") that accumulate dust particles. While the formation mechanism of such regions is still unclear, they are intriguing structure in terms of the evolution of the disk material; it may correspond to a sublimation front of volatile species, and it may also prevent radial dust mixing. In this talk, I will present recent progress in observations of dust disk structure and gas chemistry, including results from Molecules with ALMA at Planet-forming Scales (MAPS), an ALMA Large program conducting systematic study of gas emission lines in five protoplanetary disks.
The other topic is progress of sensitive line survey in molecular clouds at millimeter-centimeter wavelengths, where line confusion and background continuum levels gets lower than submillimeter wavelengths. In recent years, new "large" interstellar molecules, consisting of more than 10 atoms, have been detected by using wideband receivers mounted on a large single telescope. What is particularly noteworthy is that they may be deeply related to the materials of life. Specifically, ethanolamine (NH_2CH_2CH_2OH), an element of the phospholipids that form the compartment in a living thing, and cyanomidyl radial (HNCN), the simplest species having NCN backbone that nucleobases contain, have been detected in a giant molecular cloud in the Sgr B2 complex. In addition, molecules that are promising precursors of amino acids (such as formamidine and methylamine) have also been detected. I will review these recent developments.
While more results are expected to be obtained from these instruments in the near future, a breakthrough in 2030s will be realized by ngVLA, the next-generation radio interferometer operated at wavelengths of 2.6mm-25cm. In the last part of this talk, I will introduce the outlook for the construction of ngVLA and discuss its expected role in the context of astrobiology.
One of them is high resolution imaging of a protoplanetary disk at millimeter/submillimeter wavelengths by ALMA. A protoplanetary disk as well as the central star gain their masses in the protostellar stage at which the disk-star system is deeply embedded within the circumstellar envelope. High resolution observations with ALMA revealed that chemical composition of gas was altered at the accretion shocks of disk outer edge, showing the importance of studying gas compositions at small scales. It has been unraveled by dust continuum imaging at high-angular resolution that ring-like structure is ubiquitous in the disks around T Tauri stars, and these rings are believed to be high-pressure regions (so called "pressure bumps") that accumulate dust particles. While the formation mechanism of such regions is still unclear, they are intriguing structure in terms of the evolution of the disk material; it may correspond to a sublimation front of volatile species, and it may also prevent radial dust mixing. In this talk, I will present recent progress in observations of dust disk structure and gas chemistry, including results from Molecules with ALMA at Planet-forming Scales (MAPS), an ALMA Large program conducting systematic study of gas emission lines in five protoplanetary disks.
The other topic is progress of sensitive line survey in molecular clouds at millimeter-centimeter wavelengths, where line confusion and background continuum levels gets lower than submillimeter wavelengths. In recent years, new "large" interstellar molecules, consisting of more than 10 atoms, have been detected by using wideband receivers mounted on a large single telescope. What is particularly noteworthy is that they may be deeply related to the materials of life. Specifically, ethanolamine (NH_2CH_2CH_2OH), an element of the phospholipids that form the compartment in a living thing, and cyanomidyl radial (HNCN), the simplest species having NCN backbone that nucleobases contain, have been detected in a giant molecular cloud in the Sgr B2 complex. In addition, molecules that are promising precursors of amino acids (such as formamidine and methylamine) have also been detected. I will review these recent developments.
While more results are expected to be obtained from these instruments in the near future, a breakthrough in 2030s will be realized by ngVLA, the next-generation radio interferometer operated at wavelengths of 2.6mm-25cm. In the last part of this talk, I will introduce the outlook for the construction of ngVLA and discuss its expected role in the context of astrobiology.