Hayashi tracks of protostars and Hertzsprung-Russell diagram

Hayashi tracks

The Hayashi tracks show the life of a star and how it occupies its place in the HR diagram.

The stars with masses less than Sun occupy the lower right part of HR diagram. They remain there for most of there life.

The stars like our Sun take some time to come in the main sequence section. Also, they remain there for quite a long time.

Stars more massive than our Sun are the ones who move to the main sequence fastest and also are the ones who die quickly. Also, these stars are very important for astronomers as they end up in a supernova explosion or a neutron star and even blackholes.

Hertzsprung-Russell diagram

The most famous diagram in astronomy is the Hertzsprung-Russell diagram. This diagram is a plot of luminosity (absolute magnitude) against the colour of the stars ranging from the high-temperature blue-white stars on the left side of the diagram to the low temperature red stars on the right side.

This diagram below is a plot of 22000 stars from the Hipparcos Catalogue together with 1000 low-luminosity stars (red and white dwarfs) from the Gliese Catalogue of Nearby Stars. The ordinary hydrogen-burning dwarf stars like the Sun are found in a band running from top-left to bottom-right called the Main Sequence. Giant stars form their own clump on the upper-right side of the diagram. Above them lie the much rarer bright giants and supergiants. At the lower-left is the band of white dwarfs - these are the dead cores of old stars which have no internal energy source and over billions of years slowly cool down towards the bottom-right of the diagram.

From the HR diagram, it can be observed that, 80% of the stars are found in the main sequence. Our Sun is at the position corresponding to 1 on luminosity axis and 6000K on temperature axis.

The reason why so many stars are in the Main sequence region is because majority of the stars are new and young. After about 5 billion years our Sun will be a red giant and it will move to the giants section in the HR diagram.

After the red giant phase of Sun is over, it will become a white dwarf star and hence, will move to the bottom part of HR diagram where there are the white dwarfs.

Magnetars

Another class of neutron star is known as a ‘magnetar’, due to their ultra-strong magnetic field. Their magnetic field intensity is indeed about 100 thousand millions Tesla, a thousand times more than an ordinary neutron star.

By comparison, Earth’s magnetic field is about five parts over 100 000 of a Tesla (most media used for data storage can be erased if they are exposed to a magnetic field of one thousandth of a Tesla).

Magnetars are a rare type of neutron star, with powerful magnetic fields making them prone to occasional violent outbursts. Only a small handful of these curious beasts have been found in our galaxy, but new research from the Chandra X-ray Observatory implies that they may be a lot more common than previously expected. They may simply be in hiding.

Gravitational waves

Albert Einstein's General Theory of Relativity predicted about gravitational waves way back in 1916. But even after so many years, we are still struggling to detect them!

What is a gravitational wave?
Most scientists describe gravitational waves as "ripples in space-time." Just like a boat sailing through the ocean produces waves in the water, moving masses like stars or black holes produce gravitational waves in the fabric of space-time. A more massive moving object will produce more powerful waves, and objects that move very quickly will produce more waves over a certain time period.

Gravity affects the shape of space and time. Paths of light and massive bodies curve under its influence. When something churns space-time with enough energy – say a supernova explosion or two black holes in orbit around each other – the distortion spreads out in ripples, like a rock dropped in a pond. Those ripples are called gravitational waves. These are very weak but, if the accelerating object has enough mass, it should be possible to spot them.

Invariance of c

We all have heard that speed of light (c) is constant and no one can go faster than c. Ever wondered why is it constant? How was it proved?

The speed of light in a vacuum is 186,282 miles per second (299,792 kilometers per second), and in theory nothing can travel faster than light. In miles per hour, light speed is, well, a lot: about 670,616,629 mph. If you could travel at the speed of light, you could go around the Earth 7.5 times in one second.

Blackbody force: Radiation induced attractive force stronger than Gravity?

Black-body radiation can give rise to a net attractive force between tiny objects. That is the claim made by physicists at the University of Innsbruck in Austria, who have calculated the strength of this new force between a speck of dust and a hydrogen atom. The team believes that in some situations the force could be more significant than gravity – which means that its presence could have important effects on the behaviour of clouds of gas and dust in space.

The new attractive force—which the scientists call the "blackbody force"—suggests that a variety of astrophysical scenarios should be revisited.

The discovery that blackbody radiation can impart an overall attractive force on nearby objects could have great significance for many astrophysical scenarios, in particular the interaction between interstellar gas and dust grains. The findings could also have applications in experimental set-ups, such as the effects of hot microstructured surfaces in vacuum chambers. However, the scientists note that the attractive blackbody force will be difficult to measure in the lab because it will be very weak under typical laboratory conditions.

Do we live in a brain or a brane?

Ever wondered how those pills and tablets you take work?

In our life we take many medicine prescribed by our doctors. But what happens to them once they are inside our body? How do these medicines know what they are supposed to do?

The most common route for medications
The most common route is taking medication by mouth (oral). From here the medication has a journey to make that starts from our mouths to the target area.

Medicines in the digestive system

When medicines reach the stomach, some will start to dissolve. A few medicines will be absorbed into the stomach lining, others will move onto the small intestine. However, a number of tablets that are in capsule form or specially coated, will remain intact until they reach the small intestine. This is because if the medicine wasn't protected in this way, the contents would be destroyed by the hydrochloric acid in the stomach. In addition some other medications have special coverings to protect the stomach lining as these tablets may induce higher levels of hydrochloric acid that is harmful.

Medications not processed fully by the stomach move into the small intestine. They are absorbed into the lining of the small intestine.

Ever dreamed of charging your electric car in less than two minutes?. Guess what? Your dream has just become true!

Tesla Motors unveiled a system that will let drivers swap out the battery in a Model S in about 90 seconds, which is less time than it takes to fill up a traditional car at the pump.

"The only decision you need to make when you come to one of our Tesla stations is, do you prefer faster or free,"said Elon Musk, Chief Executive Officer of Tesla.

Spontaneous Human Combustion

Spontaneous human combustion or SHC is in the news again as a boy from Tamil Nadu, India keeps catching fire when nothing combustible is around him. Doctors are baffled by this rare condition and say that he emits highly combustible gases from pores of his body.

Let's take a look at what exactly is this SHC?
The first record of spontaneous combustion dates back to 1641 when Danish doctor and mathematician Thomas Bartholin described the death of Polonus Vorstius – who drank wine at home in Milan, Italy, one evening in 1470 before bursting into flames.

Since then more reports of spontaneous combustion have been filed and linked to alcoholism.