astronomy 1

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Rocket clouds
astronomy 1 by Mind Map: astronomy 1

1. emission nebulae

1.1. associated with hot young 0 and B stars

1.1.1. produce>ultraviolet radiation

1.2. formed of ionized gases that emit light of > wavelengths

1.3. most common source of ionization; high-energy photons emitted from a nearby hot star

2. dark nebulae

2.1. vast cloud of gas molecules/dust grains

2.1.1. dust grains formed in the outer region of stars:cool supergiants

2.2. ice condense on->form 'mantle':increse size->30nm

2.3. low density(mainly made of h20)

2.4. vast size->appear dark->scatter all light->hardly see

2.4.1. visible light emitted from center of our Galaxy is 100% extinguished by thedust clouds between us and its center

2.5. appearance affected by

2.5.1. hot stars disrupted by radiation pressure stellar winds is a flow of gas ejected from the upper atmosphere of a star

2.5.2. shock from nearby supernovaes

2.5.3. gravitational effects from others

2.6. obsreve->use lowest magnification->contrast btweeen dark nebulae and the backgroung star fields

3. reflection nebula

3.1. shine by light reflected from stars within

3.2. select light from a particular wavelength

3.3. hard to obeserve'cause

3.3.1. interstellar reddening

3.3.2. light shine upon grains->blue light is scatter

3.4. some types reside within the same cloud f emission nebula

3.4.1. ex:trifid nebula

4. molecular clouds

4.1. density+size permit formation of molecules(c0,h2,h20)->stars

4.2. low temp->hard to observe

4.3. gigiantic and made of mainly h20

4.4. >than the average density of our galaxy~<the air we breath

4.5. occurs in spiral arms of our galaxy

5. protostars

5.1. very young star that is still gathering mass from its parent molecular cloud

5.2. FORMATION:cloud fragment collapses under the force of self-gravity and an opaque, pressure supported core forms inside the collapsing fragment.

5.3. the infalling gas is depleted, leaving a pre-main-sequence star, which contracts to later become a main-sequence star at the onset of Hydrogen fusion.

5.4. outer layer:cooolll and opaque->energy released as radiation from shrinkage of inner parts cannot escape.only way:::CONVECTION.

5.4.1. the heat transfer due to the bulk movement of molecules within fluids

5.4.2. -> temperature remains more or less constant as the protostar shrinks, luminosity decreases because the radius decreases evolutionary track moves downward on the H-R diagram. temperature drops (to carry the heat outward)=>pressure drops more (as there is less and less weight bearing down u go out), so the density drops a great deal

5.4.3. outward by convection inner ,radiation in stars of mass > 4M

5.4.4. outward by radiative in >0.8>4.+convection in outer layer

5.4.5. outward by convection of the stars with mass of less than 08M.

5.5. cloud of denser materials clumped->rotate

5.5.1. conservation og angular momentum

5.5.2. materials flatten->form PROTOSTELLAR DISK

6. t_tauri star

6.1. protostars change luminousity irregular in just few days

6.2. structure formed by diffuse material in orbital motion around a massive central body.

6.3. absorb +emit light in their spectrums

6.4. mainly sorrounded by accretion disk

6.4.1. significant fraction on star's mass

6.5. has spectral line of lithium

6.6. less thn 1M,1 million yo

7. bioplar outflow

7.1. comprises two continuous flows of gas from the poles of a star.

7.2. In collapsing cloud of gas and dust, th magnetic field dragged to the centre

7.2.1. no rotationally supported disc can form, unless the tiny grains are removed from the cloud by growing or coagulating into bigger grains

8. formation of stars strigger

8.1. O+B type stars->emits immense amount of radiation

8.1.1. ->surround gas ionize

8.1.2. h|| region formed in bigger molecular clouds orion nebulae is a HII region.short-lived blue stars created in these regions emit copious amounts of ultraviolet light that ionize the surrounding gas

8.2. expansion

8.2.1. stellar winds+radiation from o,b stars carve out cavity->expands h|| regions

8.2.2. stellar winds supersonic->shock wave associated with->expand+collide with molecular clouds compress cloud further new o+B star formation occur origginal O+B type->disperse

9. galactic strar clusters

9.1. are group of young stars

9.2. high mass star evolve(give off gas/heat) faster t low-mass star

9.2.1. ->high-mass star shine brightly

9.2.2. low-mass star cocoon by dust mantles radiation from new hot/bright star may disturb low-mass star->reduce final mass

9.3. trapezium (orion nebuae)

9.3.1. large clusters

9.3.2. contain A,H,G type stars

10. SUN

10.1. structures

10.1.1. core temp+pressure enough for nuclear fusion h20->h release energy helium join->helium core

10.1.2. radiative core energy transfer by radiation than convection

10.1.3. tacocline boundary btween 2 zones

10.1.4. convection zone close to surface sun is cool+diffuse to occurs convection =>outward heat transfer outward by primaliry photons of x-ray (transport energy affect by opacity of gas photon flow)

10.1.5. phophosphere deepest part observe with visible light sun->gaseous->not have visible defined surface =>VISIBLE SURAFCE HAS 2 PARTS gas <dense earth atmosphere

10.1.6. atmosphere gas halo around the sun can see during solar eclipes contain chromosphere CORONA solar transition region heliousphere

11. proton-proton chain

11.1. h20->h

11.2. proton's kinetic energy high enouf to overcome mutual electrostatic

11.2.1. :force btween 2 electric charged particles

11.3. deuterium producing in sun are rare

11.3.1. deuterium->h2:one of 2 stable isotopes of h