The Ophiuchus Superbubble is an astronomical phenomenon located in the

Ophiuchus Ophiuchus () is a large constellation straddling the celestial equator. Its name comes from the Ancient Greek (), meaning "serpent-bearer", and it is commonly represented as a man grasping a snake. The serpent is represented by the constella ...

constellation, with a center around ℓ ≈ 30 °. This giant

superbubble A superbubble or supershell is a cavity which is hundreds of light years across and is populated with hot (106 K) gas atoms, less dense than the surrounding interstellar medium, blown against that medium and carved out by multiple supern ...

was first discovered in a 2007 study of extraplanar

neutral hydrogen The hydrogen line, 21 centimeter line, or H I line is the electromagnetic radiation spectral line that is created by a change in the energy state of neutral hydrogen atoms. This electromagnetic radiation has a precise frequency of , w ...

in the disk-halo transition of the Galaxy. The top extends to

galactic latitude The galactic coordinate system is a celestial coordinate system in spherical coordinates, with the Sun as its center, the primary direction aligned with the approximate center of the Milky Way Galaxy, and the fundamental plane parallel to an a ...

s over 25°, a distance of about 7 kpc. The

Green Bank radio telescope The Robert C. Byrd Green Bank Telescope (GBT) in Green Bank, West Virginia, US is the world's largest fully steerable radio telescope, surpassing the Effelsberg 100-m Radio Telescope in Germany. The Green Bank site was part of the National Radi ...

has measured more than 220,000 HI spectra both in and around this structure.

Structure

The movable 110 meter antenna of a radio telescope made it possible to take pictures of several neighboring regions of the sky, resulting in a folded mosaic in which an area filled with

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...

was highlighted. Near this area the interstellar gas is disturbed and many ejections are evident. The total mass of HI in the system is ≈ 10⁶ M☉, with an equal mass of H⁺. The base of the structure consists of HI "whiskers" measuring several hundred pc wide and its halo extends over more than 1 kpc. The "whiskers" have a vertical density structure suggesting that they are the walls of the bubble and were created by a lateral rather than an upward movement. They resemble the vertical streaks of dust seen on

NGC 891 NGC 891 (also known as Caldwell 23, the Silver Sliver Galaxy, and the Outer Limits Galaxy) is an edge-on unbarred spiral galaxy about 30 million light-years away in the constellation Andromeda. It was discovered by William Herschel on October ...

Geographical

The superbubble is located 23 thousand light-years from the Earth, and the object itself is "raised" 10 thousand light-years above the plane of the galaxy. According to the Kompaneets model of an expanding bubble, the age of this system is ≈ 30 Ma, and its total energy content is ~ 10^53

erg The erg is a unit of energy equal to 10−7joules (100 nJ). It originated in the Centimetre–gram–second system of units (CGS). It has the symbol ''erg''. The erg is not an SI unit. Its name is derived from (), a Greek word meaning 'work' o ...

. It may be at the stage when expansion stops and the shell begins to experience significant instabilities. This system offers an unprecedented opportunity to study several important phenomena at close range, including the evolution of superbubbles, turbulence in the HI shell, and the magnitude of the ionizing flux over the galactic disk.

Formation hypothesis

The

is hypothesized to be based on a massive cluster of young stars. The brightest of these stars exploded one after another, but since bright stars have a short lifespan (about 10 million years), a difference of a couple of million years essentially meant they all exploded at the same time. With a high degree of probability, the matter was "pushed" out of the galactic plane by such explosions, resulting in the inflation of the bubble. The

interstellar matter In astronomy, the interstellar medium is the matter and radiation that exist in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and cosmic rays. It fills interstellar ...

itself is present in most galaxies and is mainly neutral or ionized hydrogen. Such structures are capable of influencing the distribution of chemical elements in the galaxy: heavy nuclei that are born inside stars are ejected during an explosion together with gas, which - in the form of a "superbubble" - transports them over considerable distances.

Reference

{{Reflist Ophiuchus (constellation)