What is a star ?

Question

What is a star ?

Answer 1

stars are massive balls of plasma that generate energy using nuclear fussion, in which hydrogen is converted to helium as itmoves towards the surface giving off massive amounts of left over heat and energy

Answer 2

Stars are essentially huge balls of gas (mainly hydrogen). The extaordinarily amounts of bright light and heat they emit is caused by nuclear reactions happening within the star. Perhaps the easiest way of describing what is happening inside a star is to explain how they are born:

Stars are born in vast clouds of gas and dust. Dense clumps start to form in these clouds and these clumps start to exert gravitational pull. They start to suck in more gas from the surrounding cloud and this increases their gravitational pull which sucks in more gas. This cycle continues and just like a haystack in summer the inside of the protostar starts to get very hot. If enough material is is hoovered up from the surrounding gas and dust, the protostar will hit a critical point in its life. As the core temperature reaches about 10 million degrees centigrade it ignites, nuclear reactions begin and as they say in Hollywood a star is born.

With its own gravity trying to collapse the star inwardly and the nuclear reactions trying to blow the star apart it manages to find an equilibrium and will settle down to burn for anything between a few million years and thousands of million years. (Our sun is about half way through its 10,000 million year life cycle.)

Answer 3

huge balls of hydrogen

Answer 4

A star is a massive, luminous ball of plasma. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth. Other stars are visible in the night sky, when they are not outshone by the Sun. For most of its life, a star shines because thermonuclear fusion in its core releases energy that traverses the star's interior and then radiates into outer space. Almost all elements heavier than hydrogen and helium were created by fusion processes in stars.

Astronomers can determine the mass, age, chemical composition and many other properties of a star by observing its spectrum, luminosity and motion through space. The total mass of a star is the principal determinant in its evolution and eventual fate. Other characteristics of a star are determined by its evolutionary history, including the diameter, rotation, movement and temperature. A plot of the temperature of many stars against their luminosities, known as a Hertzsprung-Russell diagram (H–R diagram), allows the age and evolutionary state of a star to be determined.

A star begins as a collapsing cloud of material composed primarily of hydrogen, along with helium and trace amounts of heavier elements. Once the stellar core is sufficiently dense, some of the hydrogen is steadily converted into helium through the process of nuclear fusion.[1] The remainder of the star's interior carries energy away from the core through a combination of radiative and convective processes. The star's internal pressure prevents it from collapsing further under its own gravity. Once the hydrogen fuel at the core is exhausted, those stars having at least 0.4 times the mass of the Sun[2] expand to become a red giant, in some cases fusing heavier elements at the core or in shells around the core. The star then evolves into a degenerate form, recycling a portion of the matter into the interstellar environment, where it will form a new generation of stars with a higher proportion of heavy elements.[3]

Binary and multi-star systems consist of two or more stars that are gravitationally bound, and generally move around each other in stable orbits. When two such stars have a relatively close orbit, their gravitational interaction can have a significant impact on their evolution.[4

*Vietnamese:Một ngôi sao là một thiên thể chứa chủ yếu vật chất ở trạng thái plasma, khối lượng khoảng từ 1020 đến 1040 kg, duy trì ở nhiệt độ hàng nghìn độ K, do đó tỏa ra bức xạ vật đen tương ứng có cực đại trong phổ nhìn thấy đến UV gần, nhờ các phản ứng nhiệt hạch trong lòng. Các ngôi sao thường có hình dạng gần hình cầu, tự duy trì trạng thái cân bằng thủy động lực học, nhờ sự cân bằng giữa áp suất bức xạ điện từ phát ra từ bên trong với trường hấp dẫn của bản thân.

Các sao thường là trung tâm của một hệ hành tinh, trong đó các hành tinh và các thiên thể khác (như sao chổi, khí và bụi, ...) chịu ảnh hưởng lực hấp dẫn của sao trung tâm và bay quanh sao trung tâm. Mặt Trời là ngôi sao gần chúng ta nhất và là ngôi sao trung tâm của Hệ Mặt Trời.

Có những hệ gồm hai sao bay xung quanh nhau, tạo thành sao đôi. Các sao đôi thường không có hành tinh bay quanh, do hệ như vậy không cân bằng bền. Cũng lý do này, các hệ gồm 3 sao thường có một sao đôi, hai sao bay sát nhau, và một sao đơn nằm xa. Các nhóm gồm nhiều sao có mối liên kết hấp dẫn với nhau cũng thường chứa các sao đôi và sao đơn bên trong. Ở khoảng cách lớn hơn, các sao tụ tập, cùng với các dạng thiên thể khác, thành các thiên hà.

Môn học nghiên cứu các ngôi sao là thiên văn sao.

Answer 5

a ball of gas

Answer 6

A sun witch is like a huge ball of gas with heat and fire.

www.google.com

try that!

Answer 7

A huge ball of gass and plasma.