Top 5 Most Interesting Stars
Ever wondered what's going on up in the darkness of the universe, when you look up at the night sky? The billions of stars situated out of our reach are so pretty from distance. But some of the stars out there are going through or already went through some really interesting experiences and here are such 5 of the many more amazingly interesting stars: from the star that turns off every once in a while to the star that might be older than the universe itself!
PSR B1931+24 is a pulsar that turns on for a week and then turns off for a month. It's the only other pulsar that stops working for more than a few minutes. Still, can't beat our beloved PSR J1841-0500.
1. PSR J1841-0500: The Star That Likes To Take A Break Every Once In A While!
This star is located in the Scutum-Centaurus spiral arm of our galaxy, about 22.8 light years from Sun. It's a pulsar star; the type of star whose spin causes its light to pulse. It spins once in every 0.9 seconds- something very casual for any pulsar star. So what's interesting about this star? This star likes to disappears every once in a while!
It was discovered in December 2008 and at first was thought to be just a regular pulsar. Over the next 1 year scientists studied this star and right before when they were about to conclude the observations, this star disappeared! The group of scientists at first thought that there's some problem with their equipment but after several tests it was concluded that the pulsar was no longer there. The star turned off!
We know that about 100 out of 2000 known pulsars stop pulsating but only for a few minutes to hours. This process is called "nulling". Pulsars continuously emits radio pulses and we see them by catching these radio pulses. When they stop, they stop emitting the radio pulses as well, and therefore we can't see them during this period.
Scientists observed this mystery star for about a year and a half in the hope that the pulsar would return and then eventually it did in August 2011, after 580 days! Scientists knew that they have found a rare subspecies of pulsar.
It is still a mystery what causes these stars to go invisible. By measuring the radio pulses from the star scientists can measure how fast is it spinning. The massive currents in the magnetosphere of pulsars helps in the spinning of this star and when this current stops flowing the pulsars slows down and eventually stop. But what causes the stoppage of this current flow is not know yet.
580 days is the longest break that a pulsar has ever taken; implying that such breaks are quite rare.
Maybe somewhere out there a pulsar is taking a century old break?
2. Swift J1644+57: The Star That Got Eaten By A Blackhole
About 3.9 billion light years away in the constellation of Draco something happened. We all have heard about the "black holes" and the fact that it destroys anything that comes near it. Well, this time it's a star, Swift J1644+57.
The event took place in another, smaller galaxy. It was first noticed when scientist received a huge amount of X-rays and γ-rays from a previously quite part of the universe. On further observations it was found that the beam was coming from the center of another galaxy. Later on it was concluded that the beam was coming from a "jet" released after a black hole consumed a star. The jet accelerated away from the site of the event at 99.5% the light's speed!
Most of the galaxies contains a central super-sized black hole. According to the studies it's been suggested that the black hole involved in this event is 1 millions times larger than the mass of Sun!
This is what happens when a star fall into a black hole:
The star is ripped apart by the intense tides and leads to the formation of a gaseous disk that swirls around the black hole and gets heated up to millions of degrees. The innermost gas in the disk spirals towards the black hole, and because of the rapid motion and magnetism a dual, oppositely directed funnels are created through which some particles escape, known as jet. In case of Swift J1644+57 one of these jets pointed straight towards the Earth.
The timing considerations suggested that the star that got devoured was a white dwarf. This is for the first time that scientists witnessed this type of event from the beginning.
Another interesting fact is that the site of this event is so far away that it took 3.9 billion years for the light from there to reach Earth! So, it's pretty old event in actuality!
Watch NASA's illustration of a black hole devouring a star
3. PSR J1719-1438 and J1719-1438b: The Star That Turned Another Star In A Diamond!
If you've read my previous hub which was about the amazing planets in the universe, you might remember the diamond planet 55 Cancri e. Today I have one more such planet. But now we're discussing stars and not planets so what we have here is an ex-star, which is now a planet; and that too not just any planet but a diamond planet! Can you believe it? A star that turned into a planet?! Yes that did happen 4,000 light-years away in the constellation of Serpens.
It all started with the discovery of a millisecond-pulsar star, named PSR J 1719-1438. Pulsars are neutron stars that weighs half a million times as much as Earth but are only 20 km across. Their rotation makes them appear to pulse per rotation period and they spin up to 700 times/sec.
Later on, the motion of the pulsar suggested that it has a companion orbiting it.
Let's peek into the history of the two Stars PSR J1719-1438 and PSR J1719-1438b in very brief
There were two brother stars, PSR J 1719-1438 and PSR J 1719-1438b, forming a binary system. PSR J 1719-1438 then went into supernova and was a dying pulsar. But then it stripped the outer matter of its companion star, leaving behind only its carbon core, which has features that now classifies it as a planet. The transfer of the matter converted the dying star into an millisecond pulsar by spinning it to a very high speed. Thus a fast spinning pulsar was formed with a companion which was once a star but now a planet.
The planet PSR J 1719-1438b has a volume roughly equal to that of Jupiter but surprising it is 20 times more dense than Jupiter, making it the most densest planet of all. This planet is composed of carbon and oxygen. The high amount of pressure acting on this star-turned-planet and its high density suggests that the carbon of this planet is crystallized to form a giant diamond!
Another interesting fact about this system is that; PSR J 1719-1438b orbits PSR J 1719-1438 once in every 2.17 hours and is located at about 600,000 km, i.e the distance between this planet and the star is slightly less than Sun's diameter. That means this whole system would fit within the volume of our Sun.
4. HD 140283: The Star That's Older Than The Universe!
Now that sounds impossible. How can a star be older than universe? But believe it or not this star, HD 140283, is older than Universe according to the calculations. It is estimated that this star is 14.46 ± 0.8 billions years old, whereas the universe is 13.79 ± 0.021 billions years.
However, the exact age of the star and the universe cannot be predicted. There are uncertainties in the value. The age of this star is 14.46 ± 0.8 billions years. If you consider the lower limit i.e. if you minus 0.8 billion years it will come out to be 13.66 billion years, which is younger than the age of the universe i.e 13.79 ± 0.021 billions years. However, if you consider the upper limit, then it will be older than the universe. I guess we'll never know which one is it (or maybe in distant future), but it's a possibility, according to the current calculation methods.
Also known as the "Methuselah star", it is located about 190 light years away from us, in the constellation of Libra.
This star is the oldest star known. There are other features of this star that also suggest that it's a pretty old star. First of all it's a sub-giant star, i.e. it's not a red giant, rather heading towards the red giant stage ('nearing end' stage of a star). Secondly, it belongs to population II group of stars. Population II stars have a low content of metals. Now, in astronomy "metals" is anything that's not hydrogen or helium. Hydrogen and helium are the two elements that were produced by the big bang. So first generation of the stars (population III stars) had no metal at all. The first generation survived for only a few millions of years and then ended their lives in supernova explosions. A second generation of stars, population II, were then formed from the remnant of first generation, and this generation had some degree (but still low amount) of metals in them. Population I are the younger generations stars that has high levels of metal in them. Our Sun is an example of population I stars.
This star was born in a primeval dwarf galaxy and was later on gravitationally shredded and devoured by our emerging Milky Way galaxy over 12 billion years ago. It has an elongated orbit that encircles the milky way. Hence, it passes through our solar neighborhood, making it visible to naked eyes, with a speed of 800,000 miles per hour!
Well, this is the oldest star that we know of. Who knows there are much older stars somewhere out there?
5. HV 2112: The Star Inside A Star!
Discovered in 2014, HV 2112 is a red supergiant located about 1,99,000 light years away in the nearby dwarf galaxy called the Small Magellanic Cloud, or Nebucula Minor, in the Tucana constellation. The existence of this star was predicted about 40 years ago by physicist Kip Thorne and astronomer Anna Zytkow! In 1975 they proposed the existence of a hybrid object, known as Thorne-Zytkow object.
Thorne-Zytkow object is a type of star which is formed by the collision of a red giant or supergiant star with a neutron star. Basically what happens is: a star goes into supernova and leads to the formation of a neutron star. But then a passing by red supergiant star collides with the neutron star and absorbs it forming a hybrid star. So in other words its a star inside a star! From outside its a red supergiant whereas the core is formed by a neutron star! Isn't that cool??
These objects differ from a normal red supergiant in their chemical fingerprints. From the outside it sure looks like a red supergiant but inside it is rich in rubidium, strontium, yttrium, zirconium, molybdenum and lithium. The light emitted from HV2112 was studied and it was found that the light was highly rich in these elements. A normal red supergiant also have these components but not in such high amount.
This star is the only one of its kind! It is the first ever Thorne-Zytkow object to be discovered. But studies are still going on to confirm that HV 2112 is a hybrid star.
So let's see, which star you found the most interesting of all?
I have loved the stars too fondly to be fearful of the night.— Galileo