New Research Reveals Larger Milky Way and Revised Understanding of Stellar Distribution
TapTechNews July 12th news, Chinese astronomers deeply analyzed the data of the near-infrared stellar spectroscopic survey (APOGEE) and reconstructed the complete radial density distribution of stars in the Milky Way from the inside out. The measurement result shows that 'the Milky Way is larger than previously assumed'.
The relevant research results, titled 'The Broken-Exponential Profile and Larger Radius of the Milky Way Galaxy', were published in the international authoritative academic journal Nature Astronomy.
This research was led by Associate Professor Lian Jianhui from the Southwestern Institute of Astronomy, Yunnan University. Based on the first international large-scale near-infrared stellar spectroscopic survey (APOGEE), it comprehensively analyzed the non-uniformity, dust, and characteristics of stars in the APOGEE survey, and systematically reconstructed the true and complete surface density distribution of stars of different ages in the Milky Way from the nuclear bulge to the outer disk for the first time.
The research results of this work show that the disk structure of the Milky Way in the outer disk region (radius R > 24,000 light-years, and the solar system is located at about R 26,000 light-years) conforms to the classic exponential distribution; however, in the inner disk region (11,000 < R < 24,000 light-years), the stellar density remains almost flat and significantly deviates from the exponential distribution of the outer disk.
This result overturns the previously long-assumed hypothesis of a single exponential disk in the Milky Way and will have an important impact on the measurement of many key overall physical properties of the Milky Way.
According to the previous assumption based on the exponential disk, it was found that the radius of the Milky Way (about 10,000 light-years) is smaller than that of galaxies of the same mass and belongs to a compact galaxy.
However, based on the new stellar surface density distribution, we found that the radius of the Milky Way is almost twice that of the previous estimate (about 19,000 light-years) and is basically the same as the radius of neighboring galaxies of the same mass, indicating that the Milky Way is a typical disk galaxy in terms of galaxy size.
Associate Professor Lian Jianhui said:
Since the influence of dust extinction on photons with longer wavelengths decreases rapidly, near-infrared band observations can alleviate this problem to a large extent.
With the progress of astronomical observation techniques in recent years, especially the development of large-scale near-infrared stellar spectroscopic surveys, it provides unprecedented opportunities to solve this problem.
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