Interstellar cloud in the Milky Way Galaxy
The
Local Interstellar Cloud
(
LIC
), also known as the
Local Fluff
, is an
interstellar cloud
roughly 30
light-years
(9.2
pc
) across, through which the
Solar System
is moving. This feature overlaps with a region around the Sun referred to as the
solar neighborhood
.
[2]
It is unknown whether the
Sun
is embedded in the Local Interstellar Cloud, or is in the region where the Local Interstellar Cloud is interacting with the neighboring
G-Cloud
.
[3]
Like the G-Cloud and others, the LIC is part of the
Very Local Interstellar Medium
which begins where the
heliosphere
and
interplanetary medium
end,
[4]
the furthest that probes have traveled.
Structure
[
edit
]
The Solar System is located within a structure called the
Local Bubble
, a low-density region of the galactic
interstellar 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, its
specific 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 the
Milky Way
(0.5/cm
3
or 8/cu in), though six times denser than the gas in the hot, low-density Local Bubble (0.05/cm
3
or 0.8/cu in) which surrounds the local cloud.
[5]
[10]
In comparison,
Earth's atmosphere
at
the edge of space
(i.e. 100 km above sea level) has around 1.2
×
10
13
molecules per cubic centimeter, dropping to around 50 million (5.0
×
10
7
) at 450 km (280 mi).
[11]
The cloud is flowing outwards from the
Scorpius?Centaurus association
, a
stellar association
that is a star-forming region,
[12]
[13]
roughly perpendicular to the Sun's own direction, if assumed to be two dimensional.
In 2019, researchers found interstellar
iron-60
(
60
Fe) in
Antarctica
, which they relate to the Local Interstellar Cloud.
[14]
Interaction with solar magnetic field
[
edit
]
In 2009,
Voyager 2
data suggested that the magnetic strength of the local interstellar medium was much stronger than expected (370 to 550
pico
teslas
(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 the
solar wind
and the
Sun's magnetic field
.
[9]
This interaction with the
heliosphere
is under study by the
Interstellar Boundary Explorer
(IBEX), a
NASA
satellite mapping the boundary between the Solar System and interstellar space.
See also
[
edit
]
References
[
edit
]
- ^
"NAME LIC"
.
SIMBAD
.
Centre de donnees astronomiques de Strasbourg
. Retrieved
March 15,
2014
.
- ^
Gargaud, Muriel; et al., eds. (2011).
"Solar Neighborhood"
. pp. 1526?1527.
doi
:
10.1007/978-3-642-11274-4_1460
.
ISBN
978-3-642-11271-3
. Retrieved
2022-07-01
.
;
- ^
a
b
Gilster, Paul (September 1, 2010).
"Into the Interstellar Void"
.
Centauri Dreams
.
- ^
Linsky, Jeffrey (2020-03-23), "What lies immediately outside of the heliosphere in the very local interstellar medium (VLISM): morphology of the Local Interstellar Cloud, its hydrogen hole, Stromgren Shells, and 60Fe accretion",
Egu General Assembly Conference Abstracts
, Copernicus GmbH: 1410,
Bibcode
:
2020EGUGA..22.1410L
,
doi
:
10.5194/egusphere-egu2020-1410
,
S2CID
226032795
- ^
a
b
"Our Local Galactic Neighborhood"
. Interstellar Probe Project. NASA. 2000. Archived from
the original
on 2013-11-21
. Retrieved
2012-08-08
.
- ^
a
b
Frisch PC, et al. (September 2011).
"The Interstellar Medium Surrounding the Sun"
.
Annual Review of Astronomy and Astrophysics
.
49
(1): 252.
Bibcode
:
2011ARA&A..49..237F
.
doi
:
10.1146/annurev-astro-081710-102613
. Retrieved
2021-12-28
.
- ^
Linsky JL, et al. (November 18, 2019).
"The Interface between the Outer Heliosphere and the Inner Local ISM"
.
The Astrophysical Journal
.
886
(1): 41.
arXiv
:
1910.01243
.
Bibcode
:
2019ApJ...886...41L
.
doi
:
10.3847/1538-4357/ab498a
.
S2CID
203642080
.
- ^
Linsky JL, et al. (March 2020).
"New results concerning the environment of the heliosphere, nearby interstellar clouds, and physical processes in the inter?cloud medium"
.
Journal of Physics: Conference Series
.
1620
(1): 012010.
Bibcode
:
2020JPhCS1620a2010L
.
doi
:
10.1088/1742-6596/1620/1/012010
.
S2CID
225188522
.
- ^
a
b
"Near-Earth Supernovas"
. NASA Science. NASA. January 6, 2003
. Retrieved
February 1,
2011
.
- ^
Boulanger, F.; et al. (2000). "Course 7: Dust in the Interstellar Medium". In
Casoli, F.
; Lequeux, J.; David, F. (eds.).
Infrared Space Astronomy, Today and Tomorrow
. Les Houches Physics School. Grenoble, France. August 3?28, 1998. Vol. 70. p. 251.
Bibcode
:
2000isat.conf..251B
.
- ^
United States Committee on Extension to the Standard Atmosphere (October 1976).
U.S. Standard Atmosphere, 1976
.
NOAA
,
NASA
and
U.S. Air Force
. pp. 210?215.
OCLC
3360756
.
- ^
Nemiroff, R.; Bonnell, J., eds. (February 10, 2002).
"The Local Interstellar Cloud"
.
Astronomy Picture of the Day
.
NASA
. Retrieved
December 21,
2016
.
- ^
Nemiroff, R.; Bonnell, J., eds. (February 17, 2002).
"The Local Bubble and the Galactic Neighborhood"
.
Astronomy Picture of the Day
.
NASA
. Retrieved
December 21,
2016
.
- ^
Koll, Dominik; et al. (August 2019). "Interstellar
60
Fe in Antarctica".
Physical Review Letters
.
123
(7). 072701.
Bibcode
:
2019PhRvL.123g2701K
.
doi
:
10.1103/PhysRevLett.123.072701
.
hdl
:
1885/298253
.
PMID
31491090
.
S2CID
201868513
.
- ^
Opher, M.; et al. (December 24?31, 2009).
"A strong, highly-tilted interstellar magnetic field near the Solar System"
(PDF)
.
Nature
.
462
(7276): 1036?1038.
Bibcode
:
2009Natur.462.1036O
.
doi
:
10.1038/nature08567
.
PMID
20033043
.
S2CID
205218936
.
Further reading
[
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]
External links
[
edit
]