light years in size,[4][clarification needed] and is defined by its neutral-hydrogen density of about 0.05 atoms/cm3, or approximately one tenth of the average for the ISM in the Milky Way (0.5 atoms/cm3), and one sixth that of the Local Interstellar Cloud (0.3 atoms/cm3).[dubious – discuss][5]
The exceptionally sparse gas of the Local Bubble is the result of
supershell.[7] Other research suggests that the subgroups Lower Centaurus–Crux (LCC) and Upper Centaurus–Lupus (UCL), of the Scorpius–Centaurus association created both the Local Bubble and the Loop I Bubble, with LCC being responsible for the Local Bubble and UCL being responsible for the Loop I Bubble.[8] It was found that 14 to 20 supernovae originated from LCC and UCL, which could have formed these bubbles.[9]
Description
The Solar System has been traveling through the region currently occupied by the Local Bubble for the last five to ten million years.[10] Its current location lies in the Local Interstellar Cloud (LIC), a minor region of denser material within the Bubble. The LIC formed where the Local Bubble and the Loop I Bubble met. The gas within the LIC has a density of approximately 0.3 atoms per cubic centimeter.
The Local Bubble is not spherical, but appears to be narrower in the
Loop III Bubble. In 2019, researchers found interstellar iron in Antarctica which they relate to the Local Interstellar Cloud, which might be related to the formation of the Local Bubble.[12]
Local stars in the galactic plane (click for rotation)
Observation
Launched in February 2003 and active until April 2008, a small space observatory called
Cosmic Hot Interstellar Plasma Spectrometer (CHIPSat) examined the hot gas within the Local Bubble.[13] The Local Bubble was also the region of interest for the Extreme Ultraviolet Explorer mission (1992–2001), which examined hot EUV sources within the bubble. Sources beyond the edge of the bubble were identified but attenuated by the denser interstellar medium. In 2019, the first 3D map of the Local Bubble was reported using observations of diffuse interstellar bands.[14]
In 2020, the shape of the dusty envelope surrounding the Local Bubble was retrieved and modeled from 3D maps of the dust density obtained from stellar extinction data.[15]
Impact on star formation
As the bubble expands it sweeps interstellar gas and dust which collapse to form new stars on its surface but not inside. The Sun entered the bubble around five million years ago.[16][17]Local Bubble and its molecular clouds
In January 2022, a paper in the journal Nature found that observations and modeling had determined that the action of the expanding surface of the bubble had collected gas and debris and was responsible for the formation of all young, nearby stars.[18]
^"Our local galactic neighborhood". Interstellar.jpl.nasa.gov. National Aeronautics and Space Administration (NASA). 8 February 2000. Archived from the original on 21 November 2013. Retrieved 23 July 2013.
Media related to Local Bubble at Wikimedia Commons
