Picturing Star Birth and Death

“Stars are born in “molecular clouds”. That is to say, “star nurseries” consist of gaseous clouds mostly consisting of Hydrogen and Helium. When stars form, about 98% of their mass consists of this hydrogen and helium with the rest consisting of (about 2%) oxygen, carbon and nitrogen. Lithium may be present, but it is rapidly depleted in stars and is only found on the surface of some stars.
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— Thorburn, 1996

The process of stellar birth is quite beautiful, as are the many gaseous regions in which they are born. Take a look at some of the following images:

This image of the Orion A molecular cloud was captured with the VISTA telescope (Pandey, 2017). This telescope is able to see in the infrared light spectrum. Why is this important? Many young stars are not visible to the naked eye because they do not emit enough light in the visible light spectrum. But, they do emit a lot of light in the lower-frequency infrared spectrum, thus making them visible. The VISTA telescope is a ground-based telescope in Chile operated by the European Southern Observatory.

Here’s an image of a stellar nursery being shredded by matter interactions within young stars. Here pictured is an image of Orion Molecular Core 1 at about 1350 light years’ distance (Yeager, 2017).

The article that mentions this particular of the Perseus Molecular Cloud discusses the conditions under which stars can be formed (Sanford, 2012). Basically, the gist of it is that all stars are formed from something called the “interstellar medium”. Remember the gaseous material mentioned earlier? That’s it. The interstellar medium is made of gas and dust that exists in between stars. Cold and dense gas is the type of gas that can overcome something called “gas pressure”; gas pressure is the sort of pressure that gives a balloon its shape; all of the gaseous molecules pushing against each other, moreso when hot, less so when cold (hence the balloons appearing rather deflated after an overnight stay on the cold patio). This molecular cloud is about 300 parsecs from Earth and is one of the most active within the solar neighborhood (the Orion sector of our galaxy).

Just how cold are these molecular clouds? They’re about 10 to 30 kelvin (-263 to -243 centigrade), colder than your coldest winter day here anywhere on Earth of course. Here can be seen the Eagle Nebula (“Molecular Clouds and Dark Nebulae,” n.d.). What is a nebula? It is a gaseous cloud formed from dead stars! Often times stars are formed from these stellar remnants that are expelled during a star’s death. In the case of our star, up to 50% of its material will be returned to the interstellar medium as a nebula.

Here, within the aforementioned Eagle Nebula, we see the so-called “Pillars of Creation”. Here is the image in visible light as seen from the Hubble Space Telescope (“Star Formation: The Eagle Nebula,” n.d.). It is likely that the shape of these pillars has changed over the years (or it may no longer exist at all!), but since the light from this nebula takes about 6,500 to 7,000 years to travel from there to Earth, we are actually looking at what the nebula looked like 6,500 to 7,000 years ago (Shiga, 2007). If you wanted to see what the pillars actually look like today (2020) from Earth, you’ll have to stick around for another 6,500 to 7,000 years to see….around the year 9020.

Here is that same area as viewed with a near-infrared instrument (“Star Formation: The Eagle Nebula,” n.d.). Both images are beautiful, but if you want to take a look at what’s behind those clouds, you’re not going to be able to do it by looking at visible light; looking at other wavelengths are needed to do that.

One-size-fits-all infrared imaging isn’t exactly correct, either. Here can be seen what a far-infrared image of the same celestial object looks like (“Star Formation: The Eagle Nebula,” n.d.).

Sometimes it’s the lack of information that can say a lot about an image. Here is the same image again, only this time you’re looking at x-ray emissions. One should note that most of the x-ray light in this case is emitted outside of the pillar areas (“Star Formation: The Eagle Nebula,” n.d.).

Here can be seen the spider nebula (“The Spider Nebula,” n.d.). This nebula exists about 3066 parsecs away, about opposite the center of the Milky Way galaxy. 3066 parsecs puts this object at about 10,000 light years away, a bit farther from us than the Pillars of Creation. The bowl that can be seen in the cloud nearby has been carved out from the light emitted from the newly formed stars to the right. This image was captured by the Spitzer Space Telescope.

This is an artist’s conception of a star being born, in this case a star within the L1014 Nebula.

This image is helpful in illustrating how stars are formed, often with what are referred to as “bipolar outflows” (“Artist’s Conception of L1014,” 2004). These bipolar outflows are jets of material being blasted away from the forming star. Star formation is not a gentle process!

If you wish to see something closer to a real-life image of this process of an “infant” star being born, here’s an image of a protostar taken by the Spitzer Space Telescope. The dark envelope surrounding this protostar is over 100 times the size of the solar system (“Protostellar Envelope and Jet : HH270 VLA1,” n.d.).

Here is another young star with bipolar outflows, photo by the Hubble Space Telescope. The jets can be seen clearing the immediate area around the outflows, disturbing the surrounding gas (“A Cosmic Lightsabre,” 2015).

If a star is massive enough, when it dies, it “goes supernova”. That is, instead of gently off gassing its outer remnants, it releases its contents through a cosmic blast of sorts. In this artist’s depiction, stellar remnants form a sort of accretion disc (“fallback disc”, as it is in this case termed) around the remaining stellar corpse (in this case, a pulsar) (“Stellar Rubble May Be Planetary Building Blocks,” n.d.). A pulsar is a magnetized rotating neutron star. Supernovas like this are where all of the heavy metals in the universe originate from.

This is a photo of the Crab Nebula taken by the Spitzer Space Telescope. In the year 1054, astronomers saw a “guest star” that was so bright it could be seen not just in the night time but also during the day for some months! Here is an example of a supernova that shone as bright as 400 million suns when it exploded. This object is about as far away as the “pillars of creation”, being about 6,500 light-years away. Earth is lucky to not have been very close to such an event, else it would have irradiated and destroyed all life on the planet. This nebula, visible in different wavelength spectrums, can be seen in the boxes directly below the image.

Here’s a NASA image (courtesy of the Hubble Space Telescope) of the Red Giant Nebula located in the Large Magellanic Cloud, a so-called “satellite” of the Milky Way, about 163,000 light-years away. It is sometimes called “The Cosmic Reef” because it looks like an underwater coral structure.

Here is an image of the Butterfly Nebula taken in 2009 by the Hubble Space Telescope, its “wings” covering a total area of 3 light-years (“The Butterfly Nebula,” 2017).

Here we see “Kepler’s Supernova”. It was first seen 400 years ago by, among others, Johannes Kepler himself. The supernova is rich in iron and is 14 light years wide, getting bigger and expanding at a rate of 4 million miles per-hour (“Spitzer View of Kepler ’ s Supernova Remnant,” 2004).

Lastly, a first within photos within the stellar graveyard. As mentioned before, low-mass stars die as nebulas. Higher mass stars die in a supernova explosion. But, then there are super massive stars that die as black holes. The forces that hold matter together within such a high-mass object collapse within itself, overwhelming all subatomic forces. Though the black hole emits no light of its own, black holes can indeed be “seen” with sophisticated (understatement) equipment. Using the event horizon telescope, a network of terrestrial telescopes interconnected all around the globe, pieces together radio band observations in order to create a computational array the size of Earth itself (Schroeder, 2019).

The universe is violent and unforgiving, but looking at these objects all the way from our little corner of the universe gives a great sense of wonder and humility!

Key Words:

Accretion: Something formed by a gradual increase.

Irradiated: Flooded with radiation, in this case referring to ionizing radiation.

Nurseries: An environment in which animals or, in this case stars, are bred.

Parsec: 31 trillion kilometers.