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Speaker : Prof. H.P Singh

amol: Hello Sir, I am waiting for chat session
Kinkini:
Dear partcipants, we are going to start today's chat session at 3.30pm on all about stars and sun. Please remain online and join us
Prof.H.P. Singh:
Welcome all, Prof. Singh is here with us today for our chat sesion on "all about twinkling stars". You are welcome to ask questions to Prof. Singh on Sun and other stars. Please participate
swapnil:
Hello Sir,
swapnil:
May I know what is the difference between star and planet?
amol:
what is sun made up of?
Prof.H.P. Singh:
swapnil, tha major difference between a star and a planet is that the stars produce their own light while planets do not
amol:
how many types of stars are there?
Prof.H.P. Singh:
amol, Sun is made up of roughly 70 % Hydrogen, 28 % Helium and 2 % other heavier elements
Admin:
hello
Admin:
hello prof
Admin:
welcome sir
Prof. H. P Singh:
Hello everyone, Prof. Singh is here with us .Please goahead with your questions.
swati:
Hello Sir
swati:
May I know what is mean by CNO cycle?
Prof. H. P Singh:
CNO cycle is one of the ways stars produce energy by fusion in their cores
swati:
all stars goes through CNO cycle?
Prof. H. P Singh:
swati, CNO stands for Carbon, Nitrogen, Oxyegen
kanu:
good afternoon sir
Prof. H. P Singh:
Swati, the predominant way of energy production in low mass stars like the sun is the PP chain. More massive stars produce most of their energy by CNO cycle.
gaurav:
sir, WHY DO STARS TWINKLE
kanu: sir, what defines a galaxy?
swati:
what is the last element that can left after CNO then?
gaurav:
what is stellar scintillation
Prof. H. P Singh: Gaurav, the stars twinkle because the light from them travels through Earth's turbulent atmosphere before it reaches us.
amol:
can we see stat spots? like our sun's spot?
Prof. H. P Singh:
Hello Kanu, Galaxies are composed of millions of stars. Our Milky way is also a galaxy.
swati:
sir, what is the size of our milky way?
gaurav:
sir what is stellar scintillation
kanu:
sir how many galaxy r there?
Chota Don:
goodevng sir
krishan:
hello sir
Prof. H. P Singh:
amol, yes other stars also have spots like our sun. However, since discs of stars are not as resolved as the sun, it is difficult to 'see' them directly.
raj :
some star seems red, some blue ,and green why it is?
navneet kumar gupta:
good afternoon sir
swati:
Sir, what is the difference between star spectra and galaxy spectra?
Admin:
hello sir what is this dark matter
ravindra :
good after noon sir
Prof. H. P Singh:
swato,Milky way is several thousand light years across.
Chota Don:
sir,how do planets acquire rings?
amol:
Sir, do you belive on expansion of universe? or steady state ?
ravindra :
What is luminicity class and spectral type?
navneet kumar gupta:
when our sun became supernova what is sun size compere to present size
krishan:
what is Milky Way
Prof. H. P Singh:
swati, the spectrum from a galaxy is essentally a comosite spectrum from several stars in the field of view.
rajnee:
hello sir
Chota Don:
sir what is Black hole
kanu:
sir, can we know the age of any stars
Prof. H. P Singh:
ravindra, stars can be classfied according to their spectra, Main spectral types are assigned according to their surface temperature. Luminosity class is assigned based on the size of the star.
rajnee:
tell me about black hole
Prof. H. P Singh:
Milky way is the galaxy in which our solar system resides.
krishan:
How big are stars?
amol:
Sir, do you belive on expansion of universe? or steady state ?
search:
hello sir
raj :
sir, is there is a relation between lumnicity class and magnitude of star
rajnee:
sir how planets acquire rings?
swati:
sir, how can we measure the distance of stars which are too too long?
Prof. H. P Singh:
chota don, massive stars, stars more massive than around 30 solar masses end their lives as black holes. Their gravity is so strong that even light cannot escape their surface.
 rajnee: sir what is blue moon
 Prof. H. P Singh: Rajni, when our solar system formed and the planets formed, some debris are left which combines to form rings.
gaurav:
sir How big are stars?
ravindra :
What happend when sun complete his life ?
swati:
Sir, I read that you are working on synthesis of star spectra? what is mean by synthesis?
rajnee: how can we explain black whole
gaurav:
What are dark matter and dark energy
navneet kumar gupta:
Sir, Which unit use for mesurement lenth between to stars
Prof. H. P Singh:
navneet, the sun will eventually become a white dwarf with its size comparable to that of the earth. search: sir why Oort cloud not a disc
rajnee:
sir,how star born
Prof. H. P Singh:
navneet, there is no particular unit used. If the distance between them is too large, it is more convenient to use either LIGHT YEAR or PARSEC instead of KM.
raj :
sir once again i repeat why a star seems red, blue or any other colour. Is it due to doppler's effect or due to age of a star
thakur:
If there is no gravity in space, why do "shooting stars" fall?
rajnee:
sir, explain how jet propulsion enginess work?
Prof. H. P Singh:
rajnee, stars form by gravitational contraction of molecular gas clouds of Hydrogen.
rajnee:
sir,how a star born
Prof. H. P Singh: thakur, You do not see shooting stars in outer space. Shooting stars are meteorites that enter the earths atmosphere and burn because of friction.
search:
sir, if there is no gravity in space, why do shootings starts fall
kanu:
sir, how do we calculate the age of a star, is it possible....
abdul:
hi sir,
navneet kumar gupta:
sin, all the stars of universe get energy same process of sun or different
gaurav: sir What are dark matter and dark energy
Prof. H. P Singh:
raj, the star's color depends on its surface temperature. Cool stars appear red while hot stars appear blue. It has nothing to do with Doppler effect or age.
search:
sir, how can explain differ between sun and other stars
pradeep kumar:
Why are planets round
swati:
sir, when we say light travels through vacuume and vacuume menas nothing and light is particle then it does not look like a conflict with throries?
Prof. H. P Singh:
navneet, all stars on the main sequence produce energy by fusion reactions in their cores. rajnee: sir, how do planets rotate
Prof. H. P Singh:
swati, sounds needs a medium to propagate not light, which is an electromagnetic wave. gaurav: Why are planets round
swati:
but we say it is particle then it can not be a vaccumm!
raj :
that means there is no conection between color of star and its age?
Prof. H. P Singh:
gaurav, for all self gravitating bodies the most stable configuraion is a sphere.
search:
sir, who discover planet
rajnee: how planets rotates
Prof. H. P Singh:
search, different planets in our solar system were discovered by different people.
Admin:
sir what is dark matter ?
search: sir, how can u say that is planet
abdul:
sir i want to know about near by star sun, Question is : will our sun becomes a black hole?
Prof. H. P Singh:
abdul, the sun will not become a black hole
pradeep kumar:
sir What is a blue moon?
rajnee:
what mean by O B K M type starts
Meenakshi:
Good afternoon Sir
pradeep kumar: What is a blue moon?
search:
what is new definition of planets
Prof. H. P Singh:
rajnee, The stars are also classified by their spectra. Seven distinct classes are O B A F G K M. O being hottest and M being the coolest.
Meenakshi:
What is Nebulae
leena:
pranam sir
 Prof. H. P Singh: welcome, Meenakshi, Leena and Dr. Ananthi
Prof. H. P Singh:
Meenakshi, Nebulae are star forming regions.
search: now their r only 8 planets why
thakur:
sir how many full moons in a year
search:
where is ploto now
Prof. H. P Singh: search, Pluto was recently thrown out of the 'planet club'. Astronomers decided that it was too small.
swati: sir, how to define vaccuume? if light ie particle traveling through this then how one can define vaccuume?
leena:
main chand ke bare me janana chahti hun, me prasn hai kya hamlog kabhi bhi chand ke dusre side ko dekh payenge . mere kahne ka matlab kya 1000 year ya 10000 year ke bad chand ka rukh ulta hoga
rajnee:
why,acording which theory
Meenakshi:
Sir, How many Constellations in Universe?
rajnee:
may be in future their theory changed again
thakur:
how many full moons in a tropical year
search: how can they say,ploto not a member of planet now
abdul:
in what condition a star becomes a black hole.
search:
they can change their theory day by day
Prof. H. P Singh:
Menakshi, 88 constellations are popular.
search:
now they search next member of planets or not..
sukla:
what is the name of the star who is brighter then SUN
navneet kumar gupta:
sir , In one year How many minimum Ecilips
search:
sir,what is max temp of a star
Prof. H. P Singh:
abdul, If a star is more massive than say 30 times sun, its core will collapse to form a black hole.
search:
tell me abt ploto..
rajnee:
what a theory to discover a planet
Prof. H. P Singh:
search, O type stars can be as hot as 50,000 K
Meenakshi:
Sir, who is Biggest Constellations
Dr. Ananthi Jebasingh: Good Afternoon Sir
search:
what is main theory to discover a plannet
sukla:
what is the name of the star who is brighter then SUN
rajnee:
what s neutron star
Dr. Ananthi Jebasingh:
What is the temperature in the core of the sun? How do you measure it?
Chota Don:
sir,tell me about ploto
Chota Don:
where is ploto now???
sukla:
LIKE MILKY WAY GALAXY IS THERE ANY GALAXY WHICH HAS BEEN DESCRIBED
 Prof. H. P Singh: sukla, there are millions of stars which are brighter than the Sun. They do not appear so because of their distance.
sukla:
i am waiting for answers
Chota Don:
sir,ploto
ravindra :
i am waiting sir
Chota Don:
sir waiting ur reply
Prof. H. P Singh:
Dr. Jebasingh, The temperature of the core of the Sun is around 15 million Kelvin
Prof. H. P Singh:
Dr. Jebasingh, The temperature is estimated by theoretical modelling rather than by direct measurement.
thakur:
what is SETI
sukla:
what is the reason for formation of rings around the planet.why all planets don't have a rings.
Prof. H. P Singh:
chota don, Pluto is there where it was. It is just so that Astronomers have decided that it is too small to be called a planet.
Prof. H. P Singh:
thaku, SETI is SEARCH for EXTRATERRESTRIAL INTELLIGENCE
sukla:
why some planet rotate in clockwise direction and some in anticlockwise direction
Chota Don:
sir, but why
leena:
sir , apke uttar ka intezar kar rahi hun.
leena:
sir, apke uttar ki pratiksha kar rahi hun.
leena: sir, apke uttar ki pratiksha kar rahi hun.
leena:
sir, apke uttar ki pratiksha kar rahi hun.
leena:
sir, apke uttar ki pratiksha kar rahi hun.
Chota Don:
sir theory to define a planet
leena:
sir, apke uttar ki pratiksha kar rahi hun.
pradeep kumar:
What is the cosmic microwave
sukla:
wait---wait---wait
 Prof. H. P Singh: leena, there is no chance of looking at the other side of the moon in our lifetimes. But, you may like to go out in space and look at it from the other side.
Chota Don:
sir theory to define a planet
Chota Don:
sir theory to define a planet
Chota Don:
sir theory to define a planet
Chota Don:
sir theory to define a planet
gaurav:
arey leena shant ho jao
gaurav:
don don`t repeat
leena:
thank u sir, i am leaving.
swati:
sir what is mean by Neutron star?
Chota Don:
gaurav tell abt my question???
ram:
good after noon
sukla:
i am still waiting
rajnee:
life cycle of star
Prof. H. P Singh:
pradeep, do you mean cosmic microwave background ?
swati:
how to find the age of galaxy?
pradeep kumar: yes sir
swati:
what are AGN?
Prof. H. P Singh:
swati, Active Galactic Nuclei
search:
sir, what is Neutron Star
gaurav:
don.....we Can’t define ‘Planet?’ Go ask the Evolutionists! ...
Dr. Ananthi Jebasingh: Sir, What is a White Dwarf?
ram:
sir, why pluto is not listed in our solar system.
raj :
sir I am waiting for your answer.
raj : i repeat my question: that means there is no conection between color of star and its age?
sukla:
still waiting
Prof. H. P Singh:
chota don, The IAU members gathered at the 2006 General Assembly agreed that a "planet" is defined as a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.
ravindra :
What happend when sun complete his life ?
Prof. H. P Singh:
raj, The color of a star changes as the star evolves. Sun, for example, is presently is yellow and it will become cooler and redder in 2 billion years.
Prof. H. P Singh:
Dr.Jebasingh, White dwarf is a compact object, not as compact as a neutron star or a black hole. Low mass stars end their lives as white dwarfs.
ravindra :
thank u sir, one personal question, are do u bleave in god. if yes than say how much?
search:
sir, define balck hole?????
Dr. Ananthi Jebasingh:
thank you Sir, What is meant by light pollution?
search:
sir, define balck hole?????
search:
sir, define balck hole?????
search:
sir, define balck hole?????
rajnee:
sir, how long out solar system exists
Prof. H. P Singh:
ravindra, In arounf 5 billion years, sun will be unable to produce energy by fusion in its core because it will have exhausted all its fuel. The gravity will then make its core collapse to form a White Dwarf.
rajnee: sir, how long our solar system exists
Prof. H. P Singh:
search, black hole is a compact object, with gravity so huge that even light cannot escape it.
thakur:
is planet a pluto
Prof. H. P Singh:
rajnee, around 4.5 billion years.
Prof. H. P Singh:
thakur, not any more.
rajnee:
what is quasar
rajnee:
what are the phase in life cycle of stars
Admin:
sir what is dark matter ?
gaurav:
what is CBT planet
Prof. H. P Singh:
Dr. Jebasingh, Astronomers require dark skies for observations. Light pollution in the bigger cities forces astronomers to seek sites in far off mountains.
Admin:
is it not paradoxical ?
Admin:
matter which is not "matter" ?
Admin:
yet is important to hold "theory " together
Prof. H. P Singh:
admin, we have not been able to account for all the mass in the visible universe. Astronomers, therefore, believe that there has to be some unaccounted missing matter or dark matter
Prof. H. P Singh:
rajnee, they are quasi static radio sources.
gaurav:
sir last ques. .. what is cosmic variance
navneet kumar gupta:
sir which is milkey way nearest Galaxies
Prof. H. P Singh:
navneet, the nearest large galaxy is Andromeda II
ravindra :
sir i repeat , do u bleav god , if yes , say how much. do u regularly go mandir , do u attending religious function in social?
Prof. H. P Singh:
navneet, Andromeda is around 2 million light years away.
Prof. H. P Singh:
yes, I believe in god, it is just that she happens to be my mother.
 rajnee: what is new theory regards balck hole given by prof. steven hawkings
Dr. Ananthi Jebasingh:
What is gravitational microlensing?
rajnee:
what is new theory regards balck hole given by prof. steven hawkings
rajnee:
what is new theory regards balck hole given by prof. steven hawkings
rajnee:
what is new theory regards balck hole given by prof. steven hawkings
rajnee:
what is new theory regards balck hole given by prof. steven hawkings
navneet kumar gupta:
sir, how many galaxies identify by scientiest
rajnee:
what is magnatosphere
rajnee:
recently i read in newspaper that their is presence of methane gas on one of the moon of jupiter rajnee: is it true that it is the begining of life on that moon
rajnee:
is it true that it is the begining of life on that moon
rajnee:
is it true that it is the begining of life on that moon
rajnee:
is it true that it is the begining of life on that moon
Prof. H. P Singh:
Dr. Jebasingh, distant self-gravitating systems can act as objects can bend light coming from objects behind them. This is a case of gravitational lensing.
rajnee: sir,, please give me ans
Prof. H. P Singh:
Thank you very much for this live chat session and participating in the chat mode. If you have any further query, please mail your query at hpsingh@physics.du.ac.in