| Interstellar cloud | |
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.png) Diagram of surrounding stars and artist's conception of the Local Interstellar Cloud | |
| Observation data | |
| Constellation | None,Solar System is inside the nebula[1] |
| Physical characteristics | |
| Dimensions | 30 ly (9.2 pc) |
| Designations | Local Cloud, LIC |
| See also:Lists of nebulae | |
TheLocal Interstellar Cloud (LIC), also known as theLocal Fluff, is aninterstellar cloud roughly 30light-years (9.2 pc) across, through which theSolar System is moving. This feature overlaps with a region around the Sun referred to as thesolar neighborhood.[2] It is unknown whether theSun is embedded in the Local Interstellar Cloud, or is in the region where the Local Interstellar Cloud is interacting with the neighboringG-Cloud.[3] Like the G-Cloud and others, the LIC is part of theVery Local Interstellar Medium which begins where theheliosphere andinterplanetary medium end,[4] the furthest that probes have traveled.
The Solar System is located within a structure called theLocal Bubble, a low-density region of the galacticinterstellar medium.[5] Within this region is the Local Interstellar Cloud (LIC), an area of slightly higher hydrogen density. It is estimated that the Solar System entered the LIC within the past 10,000 years.[6]It is uncertain whether the Sun is still inside of the LIC or has already entered a transition zone between the LIC and the G cloud.[3][6][7]A recent analysis estimates the Sun will completely exit the LIC in no more than 1,900 years.[8]
The cloud has a temperature of about 7,000 K (7,000 °C; 12,000 °F),[9] about the same temperature as the surface of the Sun. However, itsspecific heat capacity is very low because it is not very dense, with 0.3 atoms per cubic centimetre (5/cu in). This is less dense than the average for the interstellar medium in theMilky Way (0.5/cm3 or 8/cu in), though six times denser than the gas in the hot, low-density Local Bubble (0.05/cm3 or 0.8/cu in) which surrounds the local cloud.[5][10] In comparison,Earth's atmosphere atthe edge of space (i.e. 100 km above sea level) has around 1.2×1013 molecules per cubic centimeter, dropping to around 50 million (5.0×107) at 450 km (280 mi).[11]
The cloud is flowing outwards from theScorpius–Centaurus association, astellar association that is a star-forming region,[12][13] roughly perpendicular to the Sun's own direction, if assumed to be two dimensional.[clarification needed]
In 2019, researchers found interstellariron-60 (60Fe) inAntarctica, which they relate to the Local Interstellar Cloud.[14]
In 2009,Voyager 2 data suggested that the magnetic strength of the local interstellar medium was much stronger than expected (370 to 550picoteslas (pT), against previous estimates of 180 to 250 pT). The fact that the Local Interstellar Cloud is strongly magnetized could explain its continued existence despite the pressures exerted upon it by the winds that blew out the Local Bubble.[15]
The Local Interstellar Cloud's potential effects on Earth are greatly diminished by thesolar wind and theSun's magnetic field.[9] This interaction with theheliosphere is under study by theInterstellar Boundary Explorer (IBEX), aNASA satellite mapping the boundary between the Solar System and interstellar space.
Media related toLocal Interstellar Cloud at Wikimedia Commons| Included | Earth →Solar System →Local Interstellar Cloud →Local Bubble →Gould Belt →Orion Arm →Milky Way →Milky Way subgroup →Local Group→Local Sheet→Virgo Supercluster→Laniakea Supercluster →Local Hole →Observable universe →Universe Each arrow (→) may be read as "within" or "part of". |
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| Related | |
