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Daily Space: Lagoon Nebula [1]

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Date: 2022-08-27

Visible light image of a portion of the Lagoon Nebula taken by the Hubble telescope to celebrate 28 yrs in space.

At around 4,100 light years away, the Lagoon Nebula is in the middle distance when it comes to some of the more lovely nebulas in our sky. But it’s also over 100 light years across, which makes for a large and highly visible object. It’s an “emission nebula,” with it’s cloud of gas and dust lit from the energy of all those bright new stars. That combination of size and brightness makes the Lagoon Nebula a standout in the sky this month.

Inside that bright nebula is some dark matter. Not that dark matter (though yes, that’s there too), but just matter that happens to be actually dark in the normal sense. Something called “Bok globule.” These are clouds of interstellar dust so dense that they actually block the escape of light. They show up like spots, or even holes, in the otherwise bright nebula.

First described in the 1940s by Dutch-American astronomer Bart Bok, these points where it looks like there is nothing, are really where there is the most something. They’re where the real action is. In those Bok globules are the collapsing clouds and swirling disks that are on their way to birthing new stars and new planetary systems. In this stellar nursery, the Bok globules are the delivery room.

Looking at the Lagoon Nebula, those brilliantly blue, fresh from the factory stars are busy blowing away the dust and gloom, propelling it backwards with the force of their stellar wind and the sheer pressure of their let-there-be-so-so-much light. The blue stars out in front of the nebula were once part of the cloud, as well. They started out in Bok globules. They were once in the middle of a great cloud like that seen in the heart of the nebula. But these stars have had more time to tidy up their neighborhoods, They’ve stepped outside to see and be seen.

One neat feature of this nebula is that tornado-shaped structure in the middle. That shape is being generated by the birth of an enormous O-type star. A star that’s so energetic, it actually gives off most of its light in the ultraviolet range. Most o-type stars cool after the first five million years or so, turning into B-type stars on the so called “main sequence.” Many of the stars in that image of the Lagoon Nebula are B-type stars. They are among the brightest stars in the galaxy. The brilliant blue star Rigel is over 800 light years away, but is still the 7th brightest star in the sky. That’s how bright they are.

None of them are long for this universe. Stars this big, this bright, are doomed to burn for only a few million years. The smaller ones will go through a sequence not too different from that destined for our Sun — they will cool, swell, then gradually collapse into white dwarf stars that linger for billions of years. The biggest and brightest will do something else. They’ll burn ferociously through their hydrogen, then the helium, then march swiftly right on up the periodic table until they reach stubbornly fusion-resistant iron. Then they’ll explode as a supernova. That’s certainly the fate in store for that star that’s making the “tornado.” When that happens, we’ll all be glad for that 4,100 light years of padding between us and the Lagoon Nebula family.

Bart Bok, the astronomer who first characterized those eponymous globules, was actually a hugely popular science communicator in his day. He spent thirty years in the astronomy department at Harvard University, and forty years married to American astronomer Priscilla Fairfield Bok. Both of them were incredibly accomplished, and they constantly worked together on tasks that seemed to bring them constant joy. It’s hard to think of a better life than that. In an event recognizing the contributions of the couple, the Royal Astronomical Society wrote, "it is difficult and pointless to separate his achievements from hers." That also seems hard to beat.

"I have been a happy astronomer for the past sixty years, wandering through the highways and byways of our beautiful Milky Way." — Bartholomeus Jan "Bart" Bok

T-Minus Two Days and Counting

As of Saturday morning, the massive SLS rocket and the Orion capsule that make up the craft for the Artemis I mission around the Moon are sitting at Pad 39-B at Kennedy Space Center, with an expected launch on Monday morning at 8:33am EDT. Daily Kos will cover the event live, with coverage beginning around an hour before launch.

x Meteorologists with the @SpaceForceDoD Launch Delta 45 continue to predict a 70% chance of favorable weather for launch of #Artemis I on Aug. 29. The primary weather concern for the two-hour launch window remains scattered rain showers.



Learn more: https://t.co/U1yk9CtsQ5 pic.twitter.com/03cIjVC6bm — NASA's Kennedy Space Center (@NASAKennedy) August 26, 2022

The rocket looks kind of tiny in this image. It is anything but. This is the biggest thing to leave any pad, anywhere, since Saturn V.

For those who can’t wait, Saturday brings briefings from the mission management team, as well as a 2:30 PM EDT pre-launch news conference.

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[1] Url: https://www.dailykos.com/stories/2022/8/27/2119166/-Daily-Space-Lagoon-Nebula

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