The
Local Bubble is a cavity in the
interstellar mediumIn astronomy, the interstellar medium is the gas and dust that pervade interstellar space: the matter that exists between the star systems within a galaxy. It fills interstellar space and blends smoothly into the surrounding intergalactic space...
(ISM) of the
Orion ArmThe Orion Arm is a minor spiral arm of the Milky Way galaxy some 3,500 light years across and approximately 10,000 light years in length. The Solar System and Earth are within the Orion Arm. It is also referred to as the Local Arm, the Local Spur or the Orion Spur.The Orion Arm is named for its...
of the
Milky WayThe Milky Way, or simply the Galaxy, is the galaxy in which the Solar System is located. It is a barred spiral galaxy that is part of the Local Group of galaxies...
. It is at least 300
light yearsLight Years is the seventh album by Australian singer Kylie Minogue and was released in 2000. It reached number two in the United Kingdom and one on the Australian album charts and number two in New Zealand being certified platinum there . Light Years is largely seen as Minogue's "comeback" album...
across and has a neutral
hydrogenHydrogen is the chemical element with atomic number 1. It is represented by the symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly flammable diatomic gas with the molecular formula H
2...
density of about 0.05 atoms per cubic centimetre, or approximately one tenth of the average for the ISM in the
Milky WayThe Milky Way, or simply the Galaxy, is the galaxy in which the Solar System is located. It is a barred spiral galaxy that is part of the Local Group of galaxies...
(0.5 atoms/cc), and half that for the "Local Fluff," or
Local Interstellar CloudThe Local Interstellar Cloud, casually called the Local Fluff, is the interstellar cloud through which the Solar System is currently moving. The Solar System entered the Local Interstellar Cloud at some time between 44,000 and 150,000 years ago and is expected to remain within it for another...
(0.1 atoms/cc). The hot diffuse gas in the Local Bubble emits X-rays. The very sparse, hot gas of the Local Bubble is the result of
supernovaA supernova is a stellar explosion. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months. During this short interval, a supernova can radiate as much energy as the Sun could emit over...
e that exploded within the past two to four million years.
The
Local Bubble is a cavity in the
interstellar mediumIn astronomy, the interstellar medium is the gas and dust that pervade interstellar space: the matter that exists between the star systems within a galaxy. It fills interstellar space and blends smoothly into the surrounding intergalactic space...
(ISM) of the
Orion ArmThe Orion Arm is a minor spiral arm of the Milky Way galaxy some 3,500 light years across and approximately 10,000 light years in length. The Solar System and Earth are within the Orion Arm. It is also referred to as the Local Arm, the Local Spur or the Orion Spur.The Orion Arm is named for its...
of the
Milky WayThe Milky Way, or simply the Galaxy, is the galaxy in which the Solar System is located. It is a barred spiral galaxy that is part of the Local Group of galaxies...
. It is at least 300
light yearsLight Years is the seventh album by Australian singer Kylie Minogue and was released in 2000. It reached number two in the United Kingdom and one on the Australian album charts and number two in New Zealand being certified platinum there . Light Years is largely seen as Minogue's "comeback" album...
across and has a neutral
hydrogenHydrogen is the chemical element with atomic number 1. It is represented by the symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly flammable diatomic gas with the molecular formula H
2...
density of about 0.05 atoms per cubic centimetre, or approximately one tenth of the average for the ISM in the
Milky WayThe Milky Way, or simply the Galaxy, is the galaxy in which the Solar System is located. It is a barred spiral galaxy that is part of the Local Group of galaxies...
(0.5 atoms/cc), and half that for the "Local Fluff," or
Local Interstellar CloudThe Local Interstellar Cloud, casually called the Local Fluff, is the interstellar cloud through which the Solar System is currently moving. The Solar System entered the Local Interstellar Cloud at some time between 44,000 and 150,000 years ago and is expected to remain within it for another...
(0.1 atoms/cc). The hot diffuse gas in the Local Bubble emits X-rays. The very sparse, hot gas of the Local Bubble is the result of
supernovaA supernova is a stellar explosion. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months. During this short interval, a supernova can radiate as much energy as the Sun could emit over...
e that exploded within the past two to four million years. The most likely candidate for the remains of this supernova is "
GemingaGeminga is a neutron star approximately 552 light-years away from the Sun in the constellation Gemini. Its name is both a contraction of "Gemini gamma-ray source", and gh'è minga "it's not there" in the Lombard dialect of Milan .- Pulsar :...
" ("Gemini gamma-ray source"), a
pulsarPulsars are highly magnetized, rotating neutron stars that emit a beam of electromagnetic radiation. The observed periods of their pulses range from 1.4 milliseconds to 8.5 seconds. The radiation can only be observed when the beam of emission is pointing towards the Earth. This is called the...
in the
constellation GeminiGemini is one of the constellations of the zodiac. Its name is Latin for "twins", and it is associated with the twins Castor and Pollux in Greek mythology. Its symbol is . It lies between Taurus to the west and the dim Cancer to the east, with Auriga and Lynx to the north and Monoceros and Canis...
.
Description
The
Solar SystemThe Solar System consists of the Sun and those celestial objects bound to it by gravity, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago...
has been travelling through the region currently occupied by the Local Bubble for the last five to ten million years. Its current location lies in the
Local Interstellar CloudThe Local Interstellar Cloud, casually called the Local Fluff, is the interstellar cloud through which the Solar System is currently moving. The Solar System entered the Local Interstellar Cloud at some time between 44,000 and 150,000 years ago and is expected to remain within it for another...
, a minor region of denser material within the Bubble. The cloud formed where the Local Bubble and the Loop I Bubble met. The gas within the LIC has a density of approximately 0.1 atoms per cubic centimeter.
The Local Bubble is not spherical, but seems to be narrower in the galactic plane, becoming somewhat egg-shaped or elliptical, and may widen above and below the galactic plane, becoming shaped like an hourglass.
The Local Bubble abuts other bubbles of less dense ISM, including, in particular, the
Loop I Bubble. The Loop I Bubble was created by supernovae and
stellar windA stellar wind is a flow of neutral or charged gas ejected from the upper atmosphere of a star. It is distinguished from the bipolar outflows characteristic of young stars by being less collimated, although stellar winds are not generally spherically symmetric.Different types of stars have...
s in the
Scorpius-Centaurus AssociationThe Scorpius-Centaurus Association is the nearestOB Association to the Sun. This stellar association is composed of three subgroups The Scorpius-Centaurus Association (sometimes called Sco-Cen) is the nearestOB Association to the Sun. This stellar association is composed of three subgroups The...
, some 500 light years from the
SunThe Sun is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 99.86% of the Solar System's mass....
. Other bubbles abutting the Local Bubble are the
Loop II Bubble and the
Loop III Bubble.
The Loop I Bubble contains star
AntaresAntares is a red supergiant star in the Milky Way galaxy and the sixteenth brightest star in the nighttime sky...
(also known as Alpha Scorpii) as shown on the diagram above right.
See also
- Loop I Bubble
The Loop I Bubble is a cavity in the interstellar medium of the Orion Arm of the Milky Way. From our Sun's point of view, it is situated towards the Galactic Center of the Milky Way galaxy. Two conspicuous tunnels connect the Local Bubble with the Loop I cavity .The Loop I Bubble is located...
- Gould Belt
The Gould Belt is a partial ring of stars about 3000 light years across, tilted toward the galactic plane by about 16 to 20 degrees. It contains many O- and B-type stars, and may represent the local spiral arm of which the Sun is a member — about 325 light years from its center. It is thought to be...
- Orion Arm
The Orion Arm is a minor spiral arm of the Milky Way galaxy some 3,500 light years across and approximately 10,000 light years in length. The Solar System and Earth are within the Orion Arm. It is also referred to as the Local Arm, the Local Spur or the Orion Spur.The Orion Arm is named for its...
- Perseus Arm
The Perseus Arm is a major spiral arm of the Milky Way galaxy.The Milky Way is a barred spiral galaxy with four major arms and at least two minor arms or spurs. The Perseus Spiral Arm, with a radius of approximately 10,700 parsecs, is located between the Cygnus Arm and the Sagittarius Arm...
- Superbubble
Superbubble is the astronomical term used to describe a cavity hundreds of light years across filled with 106 K gas blown into the interstellar medium by multiple supernovae and stellar winds...
- List of nearest stars
External links