The findings surprised astronomers because most galaxies form in association with a mysterious substance called dark matter or out of gas containing metals.

这一发现使天文学家感到吃惊，因为大部分星系形成都和“暗物质”有关，或者由富含气体的金属物质组成。

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Two years ago, residents in nearby Culver City evacuated their homes one night after a mysterious gas leak, prompting PXP to voluntarily shut down its operations until the county finishes an environmental review.

NPR: Oil Expansion Plans In L.A. Rile Residents