Hubble Captures NGC 4388, a Sideways Spiral Galaxy 60 Million Light-Years from Earth

Hubble’s most recent image focuses on NGC 4388, a sideways spiral galaxy undergoing tremendous change. It’s located 60 million light years away in the constellation Virgo, right in the midst of the Virgo Cluster, which contains over a thousand other galaxies. Because Hubble is looking at this galaxy from virtually straight on, what would ordinarily be a flat disk has transformed into a narrow, luminous line chock full of secrets just waiting to be unearthed.

Dark dust lanes cut through the bright middle band, throwing shadows on the innumerable stars behind them. However, there are also patches of deep red that indicate places where brand new stars are developing, as well as a plethora of small blue specks that indicate clusters of hot, young stars scattered along the faint spiral arms. If you look very carefully, you can just barely see a small halo of gas hanging around the whole thing, gradually receding into the darkness.

New measurements captured some extra light wavelengths, and suddenly a secret feature emerges: a massive plume of gas shooting out from the center, blazing a magnificent shade of blue as it stretches off to one side. This plume was absolutely invisible in the Hubble image from 2016, but it is now as visible as day. And why is it going so swiftly through the Virgo Cluster? Well, that’s all because of how it moves across the space between galaxies, which is filled with a thin, hot gas known as the intracluster medium. As the galaxy moves forward through this debris, it is really removing material from its disk.

At its heart is a supermassive black hole, a beast that weighs millions of times more than our sun. Gas is spiraling in toward it, heating up and emitting a vast amount of strong radiation. That will ionize the interior parts of the plume, making them glow. Further out, shock waves from the galaxies’ velocity may simply illuminate distant filaments. NGC 4388 is a Seyfert Type 2 galaxy, which implies it has an active nucleus hidden behind a thick veil of dust, but it still emits radiation in X-rays and other wavelengths. And those measurements in those wavelengths demonstrate the black hole’s influence spreads well beyond the center core.

NGC 4388’s appearance has been shaped over time by gravitational tugs from its sister galaxies in the cluster, and it now has the smooth outside edges of an elliptical galaxy as well as those distinct spiral characteristics right at the heart. Every detail in this image is the result of Hubble’s Wide Field Camera 3 using a mix of ultraviolet, optical, and narrowband filters to separate the starlight from the blazing gas.

NGC 4388 provides a vivid picture of how galaxies grow within dense clusters. Ram-pressure tearing the gas away could potentially slow down future star generation; in the meantime, the dynamic center keeps feeding and altering its environs.