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Astronomers find a huge relic of the disorganized tadpole galaxy | Astronomy



The altered galaxy "tadpole" has an elliptical head and a long straight tail, and is approximately one million light years, about 10 times larger than our own Milky Way Galaxy, according to the astronomer at Tel Aviv University. Dr. Noah Brosch and company -authors.

This image shows the HCG 98 group. The core of HCG 98 consists of both

This image shows the group HCG 98. The core of HCG 98 consists of the two "spots" in the center of the image. Each one is a galaxy very similar to our own Galaxy of the Milky Way. The tadpole structure covers the pair of central galaxies and was formed when the pair demolished a much smaller galaxy. Image credit: Brosch et al, doi: 10.1093 / mnras / sty2717.

The new galaxy is part of Hickson Compact Group 98 (HCG 98), a small group of galaxies located some 300 million light-years away from Earth.

"In compact group environments, we believe we can study" clean "examples of galaxy-galaxy interactions, learn how matter is transferred between members, and how newly enhanced matter can modify and influence the growth and development of the galaxy." said Dr. Brosch.

Dr. Brosch and his colleagues observed the HCG 98 group with a 28-inch (71 cm) telescope at the Wise Observatory and confirmed with additional observations with a similar 28-inch at the Polaris Observatory.

They also used Sloan Digital Sky Survey file images from the ICA Raya 82 Legacy Project.

"The extragalactic tadpole contains a system of two very normal" normal "disk galaxies, each approximately 40,000 light-years in diameter," said Dr. Brosch.

"Together with other nearby galaxies, the galaxies form a compact group."

"What makes this object extraordinary is that the tail alone is almost 500,000 light years long," added Professor Michael Rich, a member of the team and an astronomer at the University of California, Los Angeles.

"If it were within the distance of the Andromeda Galaxy, which is about 2.5 million light-years from Earth, it would reach a fifth of the way to our own Milky Way."

The giant "tadpole" was produced by the disruption of a small dwarf galaxy that was previously invisible and that mainly contained stars, astronomers found.

"When the gravitational force of two visible galaxies attracted the stars in this vulnerable galaxy, the stars closest to the pair formed the" head "of the tadpole," they said.

"The stars that remain in the victim galaxy formed the 'tail'."

The discovery is reported in the Monthly notices from the Royal Astronomical Society.

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Noah brosch et al. 2019. Hickson Compact Group 98: a complex group that merges with a giant tidal tail and a giant envelope. MNRAS 482 (2): 2284-2293; doi: 10.1093 / mnras / sty2717


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