Question

Based on what you learned about the Orion Nebula and evidence for theories of star formation, select all of the correct statements from following list.

a) The Orion Nebula is an emission nebula.
b) There is evidence that the stars in the Orion Nebula are young.
c) The Orion Nebula shines only from reflection of the light from the stars within it.
d) Many stars in the Orion Nebula are surrounded by disks of gas and dust.
e) Evidence of active star formation is found at ultraviolet wavelengths.
f) There is much more of the Orion Nebula than is visible.
g) The fact that many stars in the Orion Nebula are surrounded by disks of gas and dust proves that these disks are long-lasting.

Answer 1

The Orion Nebula is an emission nebula containing young stars, evidenced by hydrogen emission and circumstellar disks around some stars, indicating active star formation. It also has a greater extent in the infrared spectrum, though the longevity of circumstellar disks is not confirmed by their presence.

Step-by-step explanation:

The Orion Nebula is a vibrant example of a star-forming region, providing insights into the processes of stellar birth. Line (a) is true as the Orion Nebula is an emission nebula, characterized by the red glow of hydrogen gas ionized by nearby young, hot stars, as evidenced by the first line in the Balmer series of hydrogen. Line (b) is accurate since hydrogen emission and the presence of circumstellar disks revealed by the Hubble Space Telescope indicate the youth of stars within the nebula. Line (d) is corroborated by images showing circumstellar disks, analogous to the early solar nebula, suggesting that these are sites of ongoing planet formation.

However, line (c) is incorrect because the Orion Nebula is not solely a reflection nebula; it shines predominantly due to the ionization of gases. Line (e) is also true; evidence of star formation in nebulae like Orion can indeed be found in ultraviolet wavelengths because young stars emit significant amounts of ultraviolet radiation. Line (f) holds validity because infrared observations, which can penetrate dust clouds better than visible light, reveal more detail and extend the apparent size of the nebula. Line (g) is misleading; while many stars are surrounded by disks, the longevity of such disks varies and is not guaranteed to be long-lasting by their mere presence in images.