Chaotic Dwarf Galaxy NGC 4395 (George Simon)

Chaotic Dwarf Galaxy NGC 4395

Chaotic, barred-spiral, dwarf galaxy NGC 4395 lies in our cosmic backyard, only about 14 million light years away. NGC 4395 is notable in a number of ways. To begin, it is a Seyfert Type I galaxy, with an actively feeding, supermassive black hole. It has long been known that its black hole is on the "small" side, as supermassive black holes go. Up until quite recently, its black hole's mass was thought to be about 300,000 solar masses. However, the method used to reach this estimate, while quite accurate for large galaxies like our own, yields much less reliable results for dwarf galaxies, since details in the nucleus of these galaxies are more difficult to resolve. In 2019, a team of astronomers using a technique better suited to dwarf galaxies measured the mass of NGC 4395's central black hole to be a mere 10,000 solar masses. Properly speaking, that makes the black hole an intermediate mass, rather than a supermassive, black hole.

NGC 4395 is also notable for lacking a central bulge. In this way, it is similar to M33. Not unexpectedly, the lack of a bulge in these galaxies corresponds to the presence of a "small" black hole at their center, or in the case of M33, no black hole at all.

Another notable feature of NGC 4395 is its extremely low surface brightness. This characteristic perhaps explains the relative paucity of amateur images of this target. I was not sure how much detail in the galaxy I would be able to resolve with my relatively meager 5 hours of integration time. On the night I gathered the data, I was also fighting worse-than-average seeing conditions (though the transparency was pretty good). In the end, I am more or less pleased with the result.

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Description: Reprocessed from scratch, with an eye toward better highlighting of the H-alpha regions in the galaxy.

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Description: A couple of small, cosmetic tweaks.

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Astrometry.net job	7389431
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Chaotic Dwarf Galaxy NGC 4395

Chaotic Dwarf Galaxy NGC 4395

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Chaotic Dwarf Galaxy NGC 4395

Chaotic Dwarf Galaxy NGC 4395

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