A groundbreaking study by Chinese scientists has unveiled that our galaxy, the Milky Way, is significantly larger than earlier estimates suggested. By analyzing data from the APOGEE near-infrared stellar spectroscopic survey, researchers discovered that the Milky Way's half-light radius extends to about 19,000 light-years, nearly double the previously thought size.
This new measurement aligns the Milky Way with other local disk galaxies of similar mass, indicating that our galaxy is a typical disk galaxy in terms of size. The team, led by Lian Jianhui of the Southwestern Institute for Astronomy Research at Yunnan University, highlighted the advantages of using near-infrared observations. \"Due to the rapid decrease in the effect of dust extinction on longer wavelength photons, observations in the near-infrared band can greatly alleviate this issue,\" explained Lian.
For years, astronomers have struggled to map the Milky Way's structure accurately due to the high line-of-sight extinction caused by dense regions near the sun's position. Collecting data from a vast number of stars across a wide spatial range has been time-consuming and costly. However, the use of near-infrared data has allowed the team to reconstruct the complete surface density distribution of stars of different ages, spanning from the galactic bulge to the outer disk.
The study revealed that while the outer disk of the Milky Way follows a classical exponential distribution, the inner disk shows a nearly flat stellar density, deviating from previous models. \"In the past, based on the assumption of an exponential disk, it was found that the Milky Way's half-light radius (about 10,000 light-years) was smaller than that of galaxies of similar mass, categorizing it as a compact galaxy,\" Lian noted. This latest research overturns that assumption, offering new insights into the galaxy's physical properties and evolutionary history.
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Chinese scientists say Milky Way larger than previously thought
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