Rho Ophiuchi cloud complex
Encyclopedia
The Rho Ophiuchi cloud complex is a dark nebula
of gas and dust that is located 1° south of the star
ρ Ophiuchi of the constellation Ophiuchus
. At an estimated distance of , this cloud is one of the closest star-forming
regions to the Solar System
.
This cloud covers an angular area of on the celestial sphere
. It consists of two major regions of dense gas and dust. The first contains a star-forming cloud (L1688) and two filaments (L1709 and L1755), while the second has a star-forming region (L1689) and a filament (L1712–L1729). These filaments extend up to 10–17.5 parsecs in length and can be as narrow as 0.24 parsecs in width. Some of the structures within the complex appear to be the result of a shock front passing through the clouds from the direction of the neighboring Sco OB2 association
.
Temperatures of the clouds range from 13–22 K, and there is a total of about 3,000 times the mass of the Sun
in material. Over half of the mass of the complex is concentrated around the L1688 cloud, and this is the most active star-forming region. There are embedded infrared
sources within the complex. A total of 425 infrared sources have been detected near the L1688 cloud. These are presumed to be young stellar object
s, including 16 classified as protostar
s, 123 T Tauri star
s with dense circumstellar disk
s, and 77 weaker T Tauri stars with thinner disks. The last two categories of stars have estimated ages ranging from 100,000 to a million years.
The first brown dwarf
to be identified in a star-forming region was Rho Oph J162349.8-242601, located in the Rho Ophiuchi cloud. One of the older objects at the edge of the primary star-forming region was found to be a circumstellar disk seen nearly edge on. It spans a diameter of 300 AU
and contains at least twice the mass of Jupiter
. The million-year-old star at the center of the disk has a temperature of 3,000 K and is emitting 0.4 times the luminosity of the Sun.
Dark nebula
A dark nebula is a type of interstellar cloud that is so dense that it obscures the light from the background emission or reflection nebula or that it blocks out background stars . The extinction of the light is caused by interstellar dust grains located in the coldest, densest parts of larger...
of gas and dust that is located 1° south of the star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
ρ Ophiuchi of the constellation Ophiuchus
Ophiuchus
Ophiuchus is a large constellation located around the celestial equator. Its name is from the Greek "serpent-bearer", and it is commonly represented as a man grasping the snake that is represented by the constellation Serpens. Ophiuchus was one of the 48 constellations listed by the 2nd-century...
. At an estimated distance of , this cloud is one of the closest star-forming
Star formation
Star formation is the process by which dense parts of molecular clouds collapse into a ball of plasma to form a star. As a branch of astronomy star formation includes the study of the interstellar medium and giant molecular clouds as precursors to the star formation process and the study of young...
regions to the Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
.
This cloud covers an angular area of on the celestial sphere
Celestial sphere
In astronomy and navigation, the celestial sphere is an imaginary sphere of arbitrarily large radius, concentric with the Earth and rotating upon the same axis. All objects in the sky can be thought of as projected upon the celestial sphere. Projected upward from Earth's equator and poles are the...
. It consists of two major regions of dense gas and dust. The first contains a star-forming cloud (L1688) and two filaments (L1709 and L1755), while the second has a star-forming region (L1689) and a filament (L1712–L1729). These filaments extend up to 10–17.5 parsecs in length and can be as narrow as 0.24 parsecs in width. Some of the structures within the complex appear to be the result of a shock front passing through the clouds from the direction of the neighboring Sco OB2 association
Scorpius-Centaurus Association
The 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 or Sco OB2) is the nearestOB Association to the Sun. This stellar association is composed of three...
.
Temperatures of the clouds range from 13–22 K, and there is a total of about 3,000 times the mass of the Sun
Solar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
in material. Over half of the mass of the complex is concentrated around the L1688 cloud, and this is the most active star-forming region. There are embedded infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
sources within the complex. A total of 425 infrared sources have been detected near the L1688 cloud. These are presumed to be young stellar object
Young stellar object
Young stellar object denotes a star in its early stage of evolution.This class consists of two groups of objects: protostars and pre–main sequence stars. Sometimes they are divided by mass - massive YSO , intermediate mass YSO and brown dwarfs....
s, including 16 classified as protostar
Protostar
A protostar is a large mass that forms by contraction out of the gas of a giant molecular cloud in the interstellar medium. The protostellar phase is an early stage in the process of star formation. For a one solar-mass star it lasts about 100,000 years...
s, 123 T Tauri star
T Tauri star
T Tauri stars are a class of variable stars named after their prototype – T Tauri. They are found near molecular clouds and identified by their optical variability and strong chromospheric lines.-Characteristics:...
s with dense circumstellar disk
Circumstellar disk
A circumstellar disk is a torus, pancake or ring-shaped accumulation of matter composed of gas, dust, planetesimals, asteroids or collision fragments in orbit around a star. Around the youngest stars, they are the reservoirs of material out of which planets may form...
s, and 77 weaker T Tauri stars with thinner disks. The last two categories of stars have estimated ages ranging from 100,000 to a million years.
The first brown dwarf
Brown dwarf
Brown dwarfs are sub-stellar objects which are too low in mass to sustain hydrogen-1 fusion reactions in their cores, which is characteristic of stars on the main sequence. Brown dwarfs have fully convective surfaces and interiors, with no chemical differentiation by depth...
to be identified in a star-forming region was Rho Oph J162349.8-242601, located in the Rho Ophiuchi cloud. One of the older objects at the edge of the primary star-forming region was found to be a circumstellar disk seen nearly edge on. It spans a diameter of 300 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
and contains at least twice the mass of Jupiter
Jupiter mass
Jupiter mass , is the unit of mass equal to the total mass of the planet Jupiter . Jupiter mass is used to describe masses of the gas giants, such as the outer planets and extrasolar planets. It is also used in describing brown dwarfs....
. The million-year-old star at the center of the disk has a temperature of 3,000 K and is emitting 0.4 times the luminosity of the Sun.
Gallery
External links
- Astronomy Picture of the DayAstronomy Picture of the DayAstronomy Picture of the Day is a website provided by NASA and Michigan Technological University . According to the website, "Each day a different image or photograph of our universe is featured, along with a brief explanation written by a professional astronomer."The photograph is not necessarily...
- The Colorful Clouds of Rho Ophiuchi 2007 September 3
- Young Stars in the Rho Ophiuchi Cloud 2009 November 13
- Rho Ophiucus Wide Field 2010 May 24