Orion Arm

[9] The 1 Gyr population have been employed because they are significantly more-evolved objects than the gas in HMSFRs tracing the Local Arm.

Investigations have been carried out to compare both the stellar density and gas distribution along the Local Arm.

Researchers have found a marginally significant arm-like stellar overdensity close to the Local Arm, identified with the HMSFRs, especially in the region of 90° ≤ l ≤ 190°.

[8] The researchers have concluded that the Local Arm segment is associated only with gas and star-forming clouds, showing a significant overdensity of stars.

These differences in pitch angles and offsets between the stellar and HMSFR-defined spiral arms are consistent with the expectation that star formation lags behind gas compression in a spiral density wave that lasts longer than the typical star formation timescale of 107 − 108 years.

Figure 1.The observed structure of the Milky Way 's spiral arms [ 1 ]
A rough artist's depiction of the Orion Arm within the Milky Way, with features marked.
Molecular clouds around the Sun inside the Orion-Cygnus Arm
Rosette Nebula Crab Nebula Orion Nebula Trifid Nebula Lagoon Nebula Omega Nebula Eagle Nebula North America Nebula Rigel Orion's Belt Polaris Sun Betelgeuse Deneb Perseus Arm Orion Arm Sagittarius Arm
Orion and neighboring arms (clickable map)
Rosette Nebula Seagull Nebula Cone Nebula California Nebula Heart Nebula Orion Nebula Soul Nebula North America Nebula Cocoon Nebula Gamma Cygni Nebula Veil Nebula Trifid Nebula Crescent Nebula Lagoon Nebula Omega Nebula Eagle Nebula Cat's Paw Nebula Eta Carinae Nebula Crab Nebula Messier 37 Messier 36 Messier 38 Messier 50 Messier 46 Messier 67 Messier 34 Messier 48 Messier 41 Messier 47 Messier 44 Messier 45 Messier 39 Messier 52 Messier 93 Messier 7 Messier 6 Messier 25 Messier 23 Messier 21 Messier 18 Messier 26 Messier 11 Messier 35 NGC 2362 IC 2395 NGC 3114 NGC 3532 IC 1396 IC 2602 NGC 6087 NGC 6025 NGC 3766 IC 4665 IC 2581 IC 2944 NGC 4755 NGC 3293 NGC 6067 NGC 6193 NGC 6231 NGC 6383 Tr 14 Tr 16 Messier 103 Messier 29 HPer Chi Per Col 228 O Vel Perseus Arm Orion Arm Sagittarius Arm Star cluster Nebula
The nearest nebulae and star clusters (clickable map)
The Milky Way Galaxy
The Milky Way Galaxy