How spiral-shaped galaxies get their iconic shape?
Our Milky Way galaxy has an elegant spiral shape with long arms filled with stars, but exactly how it took this form has long puzzled scientists.
BY
AMIT MALEWAR
DECEMBER 11, 2019
Magnetic fields in NGC 1086, or M77, are shown as streamlines over a visible light and X-ray composite image of the galaxy from the Hubble Space Telescope, the Nuclear Spectroscopic Array, and the Sloan Digital Sky Survey. The magnetic fields align along the entire length of the massive spiral arms — 24,000 light years across (0.8 kiloparsecs) — implying that the gravitational forces that created the galaxy’s shape are also compressing the its magnetic field. This supports the leading theory of how the spiral arms are forced into their iconic shape known as “density wave theory.” SOFIA studied the galaxy using far-infrared light (89 microns) to reveal facets of its magnetic fields that previous observations using visible and radio telescopes could not detect. Credits: NASA/SOFIA; NASA/JPL-Caltech/Roma Tre Univ.
Like early explorers mapping the continents of our globe, astronomers are busy charting the spiral structure of our galaxy, the Milky Way. According to a study by the Stratospheric Observatory for Infrared Astronomy, or SOFIA- magnetic fields play an essential role.
For the study, scientists measured magnetic fields along the spiral arms of the galaxy called NGC 1068, or M77. The fields are shown as streamlines that closely follow the circling arms.
The M77 galaxy is found 47 million light-years away in the constellation Cetus. It has a supermassive active black hole at its center that is twice as massive as the black hole at the core of our Milky Way galaxy. The swirling arms are loaded up with dust, gas, and areas of intense star formation called starbursts.
The observations reveal that magnetic fields closely follow the newborn-star-filled spiral arms. It stretches across the entire length of the massive arms — approximately 24,000 light-years across. This implies that the gravitational forces that created the galaxy’s spiral shape are also compressing its magnetic field, supporting the density wave theory.
More:
https://www.techexplorist.com/spiral-shaped-galaxies-iconic-shape/28457/
