Tag: barred spiral

A serene spiral with a double blast

By Phil Plait | August 1, 2012 7:00 am

It’s been a while since I posted a devastating spiral galaxy picture, so why not now? I present NGC 1187, a gorgeous barred spiral about 60 million light years away:

[Click to galactinate, or grab the 3300 x 1900 pixel version.]

This image was taken with the Very Large Telescope to help astronomers study a star called Supernova 2007Y that exploded in this galaxy. Can you find it? Yeah, good luck with that; there are a gazillion stars in the picture. The folks at the European Southern Observatory helpfully circled it in this annotated version. Were you right?*

Anyway, this was the second supernova in NGC 1187 in recent times; it also hosted one in 1982 (which had faded into obscurity by the time the above image was taken). Most spirals have supernovae in them every century or three, so this was unusual but not necessarily weird. The rate is statistical so you might get two close together, or a long stretch without one. The last one in our Milky Way was about 170 years ago, and the last known before that was 400 years ago.

NGC 1187 is a gas-rich galaxy, and is forming lots of stars. That might lead to a higher-than-normal supernova rate, since that means more high-mass stars are being born, only to explode a few million years later. Both of the recent supernovae in NGC 1187 were of the same type – the core collapse of a high-mass star – so maybe this does play into it. I suppose time will tell. If we get an elevated rate over the next few decades, that’ll be interesting.

Astronomers will of course continue to study this galaxy and look for more supernovae. The science of that would be well worth the time, and in the meantime we would get even more lovely pictures of this spectacular island universe.

Image credit: ESO


* Liar.


Related Posts:

Discovery Channel telescope sees first light!
Setting the bar (about barred spiral galaxies)
More M95 supernova news: progenitor found!
Birth cry of a supernova

CATEGORIZED UNDER: Astronomy, Pretty pictures

Discovery Channel telescope sees first light!

By Phil Plait | July 23, 2012 12:30 pm

A new telescope has opened its eye to the heavens: the Discovery Channel Telescope – yes, that Discovery Channel – that’s part of the venerable Lowell Observatory. Sitting on a mountain top in Arizona, over the weekend the 4.3 meter telescope saw what astronomers call "first light": the first time it sees actual photons from the sky. Its first target: the lovely galaxy M 109:

[Click to galactinate, and also see pictures of the Whirlpool and Sombrero galaxies.]

M 109 is a barred spiral galaxy about 85 or so million light years away in the direction of Ursa Major, and is part of a loose group containing about 50 other galaxies both big and small. It’s the brightest in the group, and located on its far side from us.

The Discovery Channel Telescope is designed to see in optical light (the kind we see with our eyes) as well as near-infrared. I’m very glad to see it operational: as I’ve said here so many times, the more eyes we have on the sky, the better. The sky is wide and deep, and there’s so much to see and learn. With this new addition to our fleet of scientific instruments peering into the Universe, our understand will only grow.

Image credit: Lowell Observatory/DCT. Tip o’ the dew shield to astronomer Ian O’Neill for the news!


Related Posts:

The Milky Way’s (almost) identical twin
In the dark abyss, a slightly warped mirror on the Milky Way
Breaking: possible supernova in nearby spiral M95
Patchwork galaxy

CATEGORIZED UNDER: Astronomy, Pretty pictures

In the dark abyss, a slightly warped mirror on the Milky Way

By Phil Plait | February 3, 2012 7:00 am

There is just something wonderful when Hubble points to nearby spiral galaxies. Sprawling and detailed, we get both great resolution on smaller features as well as a jaw-dropping overview of a grand spiral… like, say, NGC 1073:

Yeah, I know. [Click to galactinate — I had to shrink it to fit here, and it lost a lot of the coolness when I did — or grab the 3900 x 3000 pixel version.]

NGC 1073 is a decent-sized spiral galaxy about 60 million light years away. It’s actually part of a small, tight group of galaxies many of which are far more famous (like NGC 1068). But 1073 is important because of a simple property: it looks like us.

While it’s not a perfect match, NGC 1073 does bear an interesting resemblance to our Milky Way galaxy (UGC 12158 looks more like our galaxy, but is far bigger, for example). Both have large, rectangular bars going across their centers. Bars are a bit odd, since you’d expect the arms just to wind all the way down to the center. But the gravity of a galaxy isn’t like the gravity of a solar system, with a big heavy star sitting in the center. Galaxies have their mass spread out over a long distance, so what gas and dust clouds and stars feel in the way of gravity is different, and bars are a natural outcome of that. However, they’re still not perfectly understood. Bars may form when galaxies collide, and they might be an indication of a galaxy reaching middle age. Perhaps there are other factors as well.

Studying galaxies like NGC 1073 will help us understand how bars form, and why we have one too. Remember, we’re stuck inside our galaxy and can’t see it from the outside (that picture above is an illustration based on detailed observations). It really helps our understanding of the Milky Way to observe galaxies like ours.

An important thing too is that the two galaxies are different in some ways: NGC 1073 has more open arms, for example, compared to our more tightly wound arms. Those differences are telling us something as well. What is it that makes one galaxy hold its arms closer in, and another to fling them out? Why does this galaxy have two arms, and that one three? If you can look at two galaxies that are alike except in one way, it’s easier to isolate the cause. So studying NGC 1073 is a great way to study ourselves.

It always makes me think of Nietzsche, who wrote on the nature of man, "And when you gaze long into an abyss, the abyss also gazes into you."

But on the nature of the Universe, it changes: "And when you gaze long into an abyss, your gaze falls back on yourself."


Related posts:

The Milky Way’s (almost) identical twin
Barred for life
Unwind with some spirals
Setting the bar
Sculpting a barred galaxy

CATEGORIZED UNDER: Astronomy, Pretty pictures

The Milky Way's (almost) identical twin

By Phil Plait | January 7, 2011 7:00 am

In my Top 14 Astronomy Pictures of 2010, I started off with a galaxy I called the Milky Way’s fraternal twin; it looks a lot like ours, but has some differences that were worth pointing out.

In one of those coincidences that makes me smile, only a few days later the folks at Hubble Space Telescope released another spiral galaxy image, and this one… well, it’s a beauty:

hst_ugc12158

That’s really something! It’s so pretty I made it my desktop image. Click it to see it in all its 2800 x 2400 pixel galactaliciousness.

The name of this galaxy is UGC 12158. It’s a face-on barred spiral; the bar refers to that rectangular block of stars in the center. Some spirals have a spheroidal central bulge, like Andromeda does, but quite a few have a bar-shaped hub. The Milky Way does, in fact, and observations using radio and infrared telescopes (able to pierce the dust obscuring our view) show that our bar is actually pretty hefty. The small picture here shows an illustration of the Milky Way based on these observations, and we think it’s a pretty accurate representation. The resemblance to UGC 12158 is obvious.

When I first saw this Hubble picture, I was impressed with the beauty of this galaxy I had never seen before. But then I realized something… Y’know, I have a lot of experience looking at Hubble images. I spent years working on them, and after a while you get a feel for them. It’s just practice, and you get what almost feels like instinct about some things. So when I saw this picture and I got that odd (but familiar) feeling in my head, I knew to pursue it. It didn’t take me more than a few seconds to nail it down: this galaxy is big. The size of the star images, the smoothness of the galaxy itself, the way the image feels… I just knew that this was no tiny galaxy.

So I went to the release page for it, and when I saw the distance, I was shocked: that galaxy’s not big, it’s freaking huge. Read More

CATEGORIZED UNDER: Astronomy, Pretty pictures

Setting the bar

By Phil Plait | September 24, 2010 7:00 am

Galaxies come in a lot of flavors. And even in the major categories (spiral, elliptical) there are sub-flavors… like barred spirals, which are truly cool and weird and awesome. Behold!

eso_ngc1365

Yowza. Click to engalacticate.

That’s NGC 1365, a barred spiral about 60 million light years away in the Fornax cluster, as seen by the HAWK-1 camera on the Very Large Telescope in Chile. HAWK-1 is sensitive to infrared light, from just outside our human eye’s range to wavelengths about four times longer than we can see. Those wavelengths are pretty good (though not perfect) at penetrating dust clouds in galaxies, which block visible light. So mostly what you see in images like this one is light from stars, along with gas clouds. Where you see dark lanes is where the dust is so thick it blocks even the infrared light, too.

The two major spiral arms are obvious enough, as well as some smaller ones (called spurs) too. These are not physical spirals; stars near the center of the galaxy revolve faster around the center than ones farther out, and so if the arms were "real" they’d quickly (well, over a few hundred million years) wind up into a tight little curl. But we see spiral arms in galaxies of all ages, so we know they’re not transient, and must be stable features.

Read More

CATEGORIZED UNDER: Astronomy, Pretty pictures

Sculpting a barred galaxy

By Phil Plait | June 17, 2010 7:19 am

I love big, splashy spiral galaxies. They are such eye candy, and of course their breadth and scale are magnificent. Sweeping, curved arms of stars and gas a hundred thousand light years long…

One of my favorites is NGC 253, a nearly edge-on spiral that lies roughly 11 million light years away in the constellation of Sculptor. I’ve seen it many, many times, but I was honestly surprised when a new image was released by the European Southern Observatory. I’ve never seen it like this:

eso_ngc253

Wow! Click to galactinate.

As you can see, it’s tilted pretty severely to our line of sight. You can clearly see the spiral arms, and the dust lanes wrapping around the galactic center. I was amazed to see the dust appears to be thicker on the top half than on the bottom. I was even more amazed to clearly see the bar — the elongated rectangular region in the center of the galaxy! That’s almost completely undetectable in a visible light image of the galaxy:
Read More

CATEGORIZED UNDER: Astronomy, Pretty pictures
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