Stellar NurseriesKarena Fiore

What is a Stellar Nursery?

Also known as molecular clouds, a stellar nursery is a dense region in space where new stars are made. A stellar nursery is located within a nebula

These interstellar clouds have high concentrations of molecular hydrogen and helium.

Temperatures range from 10 to 30 K

History

Nebulas were first recorded around 150 AD by Ptolemy

The first true nebula was mentioned in 954 by Abd al-Rahman al-Sufi in his Book of Fixed Stars. The nebula was distinct from surrounding star clusters

Al-Sufi also catalogued other nebulas such as the Omicron Velorum Cluster and Brocchi’s Cluster

History

In the late 1700s, the Herschels published three catalogs that listed thousands of nebulas and star clusters they had found

An updated version of the Herschels catalog was published in 1888 by J.L.E. Dreyer The New General Catalogue (NGC) is a compilation of clusters,

nebulas, and galaxies

Ways a Stellar Nursery is Formed

A cloud of gas becomes so dense that it collapses under its own gravity

A shockwave from a supernova (ex. The Crab Nebula)

When a low-mass star has lost most of its material, its temperature increases and it emits UV radiation that will ionize the surrounding gas This is a planetary nebula

The Crab Nebula (NGC 1952)

Structure of a Stellar Nursery

It is composed of mainly hydrogen and helium There are trace amounts of the other elements (under 1%)

There is also plasma (ionized gas) within the nebula

Width of millions of miles to hundreds of light years across

Planetary nebulas have a central star

Star Formation

Interstellar clouds are at a state of hydrostatic equilibrium gas pressure and the internal gravitational forces balance each other

Certain events will happen to trigger star formation Molecular clouds collide

Shockwaves of a supernova explosion

Galactic collisions

This will trigger a gravitational collapse within the nebula

Star Formation

As a molecular cloud fragment collapses under gravity, it becomes a protostar This is the early stage of a forming star

When a protostar reaches 10 million K in its core, it becomes a main-sequence star It is now able to undergo hydrogen fusion

Stars

Stars are born in clusters because the cloud in which they are formed is thousands of times more massive than each star

Brand new stars are main-sequence stars

High mass stars expand to become giants and supergiants These stars fuse hydrogen, helium, carbon, oxygen, etc.

Low mass stars eventually become white dwarfs Outer layers of star have been ejected and nuclear fusion has ceased

Life Span of a Stellar Nursery

Nebulas exist for a few million years

The radiation pressure from new stars drive away the gas of a nebula The dissipated nebula cannot be considered a stellar nursery anymore

There is not enough concentrated hydrogen and helium gas to form new stars

Cat’s Paw Nebula (NGC 6334)

In September of 2013, a newly discovered stellar nursery was found approximately 5,500 light years from Earth

 It was found with ArTeMiS, a wide-field sub-millimeter-wavelength camera It can sense interstellar dust grains that can be found inside a nebula

Cat’s Paw Nebula (NGC 6334)

Bibliography

http://en.wikipedia.org/wiki/Star_formation

http://en.wikipedia.org/wiki/Molecular_cloud

http://en.wikipedia.org/wiki/Nebula

http://www.universetoday.com/65067/newly-discovered-stellar-nurseries-in-the-milky-way/

http://www.kidsastronomy.com/nebulae.htm

www.nasa.gov

Bennett, Jeffrey O. The Essential Cosmic Perspective. 5th ed. San Francisco: Addison-Wesley, 2009. Print.

http://news.discovery.com/space/astronomy/cats-paw-nebula-star-forming-region-vista-eso-130925.htm

http://en.wikipedia.org/wiki/Star