Observational study of planetary-mass objects ("free-floating planets")

2017 Fiscal Year Final Research Report

• Project/Area Number: 25870124
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Astronomy; Solid earth and planetary physics
• Research Institution: Saitama University
• Principal Investigator: OASA Yumiko 埼玉大学, 教育学部, 准教授 (10397820)
• Project Period (FY): 2013-04-01 – 2018-03-31
• Keywords: 星惑星形成 / 褐色矮星 / 惑星質量天体 / 光赤外線天文学

Outline of Final Research Achievements

The very low-mass objects such as brown dwarfs (BDs) and extrasolar planets that are impossible to generate energy by Hydorogen burning are so faint and cool. Isolated planetary-mass objects (PMOs), also called as "free-floating planets'', that are characterized by the masses below the Deuterium burning threshold but do not rotate the star have been recently discovered. It is unclear how they form and have contributed to the initial mass function (IMF).
In order to characterize YBDs, PMOs, and their IMFs, we have carried out sufficiently deep NIR photometry and multi-object deep spectroscopy with large telescope such as Subaru, UKIRT for various clusters and molecular clouds.　A few thousands of YBD/PMO candidates have been newly revealed in all regions.　It appears that their spatial distributions and derived IMFs at very low-mass side would be dependent on the forming environment.

Free Research Field

天文学