What's this beautiful creation of the universe captured by hubble?
This beautiful image that you see right now might look like CGI but it's actually one of the most
recent amazing photos taken by the Hubble telescope. This is an actual, rare and intriguing
object out there. The striking image features a relatively rare celestial phenomenon known as a
Herbig Haro-Object or HH for short. These Herbic Haro objects are one of the most
beautiful creations in our universe, which we can sometimes observe with our own telescopes.
This particular object, named HH111, was imaged by the Hubble space telescope’s Wide Field camera
3(WFC3). HH 111 is about 1300 light years (400 parsec) distant from earth and is embedded in
a cometary molecular cloud called L1617. These breathtaking objects develop under very specific
circumstances. So in this video we will talk about how this system works, what mechanism is
involved in the formation of these objects and what’s happening in this particular system!!
Long ago when our sun was forming it’s very likely that our sun might have also produced
HH objects. This is because HH objects are bright patches of nebulosity associated with
newborn stars. These are formed as a result of young stars releasing very powerful,hot
and narrow jets of partially ionised gas which then start colliding with the nearby clouds
of gas at a very high speed. HH objects are often found in the star forming regions and
many are often seen around a single star, aligned with its rotational axis.
Herbig haro objects are a temporary phenomenon that last around a few tens of thousands of years
and can change their visibility over timescales of a few years as they rapidly move away from their
parent star into the dense clouds of interstellar space. These HH objects were first observed in
the 19th century by Sherburne Wesley and were recognised as a distinct type of emission nebula.
The first astronomers to study them were Guillermo Haro and George Herbig. Herbig and Haro were
working independently on star formation when they first analysed these objects and
recognised they were a by-product of the star formation process. These objects generally are
a result of the interaction of the jet with the gas around the star. So how does all of this work?
Well it all starts with a very large cloud of gas. This gas coalesces and initiates the formation of
a star by essentially causing the gravitational collapse of the interstellar gas itself and there
are quite a lot of these clouds around the galaxy and we have analyzed a lot of them. As more and
more of the gas collapses, the density increases and so does the opacity. This means it's hard to
see through these clouds as they no longer can radiate much energy. This raises the temperature
of the cloud which prevents any further collapse reaching a hydrostatic equilibrium.
The gas continues to fall towards the core in a rotating disk. This core is called a protostar
present right in the middle of the system. It's not really a star yet, it's just a concentration
of matter that will spin really fast at some point. Scientific observations of protostars
shows that while material is falling into the central object and accretion disk as expected,
other material is being expelled from the system in both directions, perpendicular
to the plane of the disk which is also known as a bipolar outflow. If these materials form the
bipolar outflow is travelling at very high velocities, it is commonly called as jets.
The mechanism for producing these collimated bipolar jets is not entirely understood,
but it is believed that interaction between the accretion disk and the stellar magnetic field
accelerates some of the accreting material from within a few astronomical units of the star
away from the disk plane. These jets have a lot of influence on these stars including potentially
causing the star to lose a lot of mass it would have otherwise gathered. These jets seem to be
present in pretty much every star system. They are also responsible for recycling a lot of material
and allowing the creation of other stars in the future. Apart from that a lot of various magnetic
interactions are also happening at the same time, which is probably the reason for these jets.
This magnetic interaction sometimes feeds the star allowing it to grow larger.
As these jets grow larger in power they start throwing off a lot of mass and create the HH
formations that we observe. But more importantly these jets are responsible for removing the
excess angular momentum from the spinning and so apparently if these jets did not exist the stars
would not exist either. The star would spin so fast that they would eventually fall apart and
fail to maintain their shape. But in this case these jets they remove the angular momentum and
make the star slow down just a little bit just enough for it to start growing larger and larger
but since these objects are inside larger clouds these jets as they start moving away
from the star they start to collide with parts of the clouds that are more dense and as the
jets start hitting the clouds they create a much brighter patch of this what's known as nebulosity.
We have some really amazing photos of HH 34, HH 161 to just show that. In HH-34, we can easily
see the star throwing off this very hot jet which then hits the very dense patch of a gas,
creating a highly ionized gas that glows and emits a lot of energy. These objects can last around a
few tens of thousands of years and can change their visibility over timescales of a few years
as they rapidly move away from their parent star into the dense clouds of interstellar space.
They do change a lot and they actually emit different light at different frequencies and
also change the luminosity once in a while. This timelapse By NASA on the screen
[https://upload.wikimedia.org/wikipedia/commons/b/b9/HH_34_jet_video_HST.ogv] clearly shows the
change in this jet in around 14 years. We will link this timelapse in the description too.
So overall these jest are pretty well studied phenomena. Normally they are visible in infrared
but some are visible in optical light as well. Generally however the brightest of these Herbuc
Haro objects are found at the ends of the jet, where the material is ploughed directly into the
surrounding molecular cloud. In a very dynamic fashion, they evolve over timescales of years as
shown previously in the simulation. Typical HH objects have temperatures around 11,000 kelvin.
Once these were very rare but with an improvement in our technology they are relatively more.
Till date we have observed about 600 of these HH objects, all in regions of star formation.
These HH objects are also always on the move. They move as the jet sort of passes through the
cloud and extends farther and farther away from the star system or from the protostar system
but even in the period of a few years they can change enough to be visible to the human eye.
Even though it's a slow process, if you take pictures a few years apart
you can spot the difference, which is obviously the jet moving away. But how big is all of this?
Most of the HH objects lie within one parsec or 3.26 light years of the source, although some
have been observed to be several parsecs away. They are always located along the rotational
axis of the star because that’s where the jets are released which collide with the clouds.
But these are very different from the jets of a neutron star or a balck hole.
The speed in the HH jets is much slower, it's usually under a thousand kilometers per second
or normally a few hundred kilometers per second, so about a thousand times slower
than from a neutron star or a black hole. The reason why HH111 is special is because it's
a binary star HH system. The system very likely looks like the image that you see on your screens
[https://hubblesite.org/contents/media/images/2000/05/938-Image.html?news=true].
We can see a very large jet and a slightly smaller jet going in almost perpendicular direction which
means that the two stars here are misaligned. Also interestingly enough there is also a third star,
which is not producing any jets, which you can easily see on the top left corner. As
a matter of fact this star seems to have been kicked out from the system.
HH 111 is about 1300 light years (400 parsec) distant from earth, so you need a very powerful
telescope if you want to see any of this yourself. The new image of HH 111 was made from separate
exposures taken in the infrared region of the spectrum with Hubble’s Wide Field Camera 3 (WFC3).
Four filters were used to sample various wavelengths. The color results from
assigning different hues to each monochromatic image associated with an individual filter.
So telescopes and technology too are very important in our exploration of such objects. But
there is still a very interesting part about these HH objects left. HH objects are not only formed
because of stars but also smaller stars like brown dwarfs. In 2017 scientists discovered at least one
brown dwarf or proto brown dwarf that seems to be forming these jets and also hh objects as well.
But not much is known about them and much of the research is still going on.
In the future we will find more and more about these strange and beautiful objects
as our technology improves over time. Also this phenomenon seems to exist everywhere in the
universe and seems to help a lot of stars evolve in a certain way and those hets surely help a lot.
What do you guys think about these intriguing visual phenomena?
Can more HH objects exist around us? Let us know your thoughts and questions in the
comment section below. And don’t forget to like the video and subscribe to our channel
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