An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

The gas and dust that exists in open space between the stars. See also → interstellar medium.

→ interstellar; → matter.

The environment containing the → interstellar matter, consisting of gas (mostly hydrogen) and dust. Even at its densest phase, the interstellar medium is emptier than the best vacuum man can create in the laboratory, but because space is so vast, the interstellar medium still adds up to a huge amount of mass.

→ interstellar; → medium.

Any molecule that occurs naturally in clouds of gas and dust in the interstellar medium. So far more than 140 species have been discovered, many of which nonexistent on Earth.

→ interstellar; → molecule.

A body other than a → star or → substellar object located in → interstellar space and not → gravitationally bound to a star. Its → hyperbolic orbit would indicate an object not bound to the Sun. The first known ISO is → 1I/'Oumuamua. ISOs are icy → planetesimals that are expected to behave like the → long-period comets of the solar system; volatile ices sublimate when the ISO approaches the Sun, developing a → coma and a → dust tail -- features that should make them bright and therefore easy to spot. The rocky ISOs, on the other hand, only reflect sunlight. As their → albedo is expected to be extremely low they become dark (after eons of bombardment by high-energy cosmic rays), they would be extremely faint and hard to detect (Hainaut et al., 2018, The Messenger 173, 13).

→ interstellar; → object.

The polarization of starlight caused by aligned → interstellar grains, so that initially → unpolarized light from a star is partially polarized by the time it reaches the Earth.

→ interstellar; → polarization.

A global ionizing radiation in the → interstellar medium provided by various sources all together.

→ interstellar; → radiation; → field.

The dimming of light during its travel in the → interstellar medium due to absorption by → intervening → dust grains. Since shorter wavelengths are particularly affected, the spectrum of the light is increasingly dominated by the long wavelength end of the spectrum. As a result, the light is "reddened" as it travels through space. Robert J. Trumpler (1886-1956), a Swiss-American astronomer, was the first to produce a definite evidence of the existence of → interstellar extinction and to estimate its magnitude (1930).

→ interstellar; → reddening.

A graph showing the relation between → interstellar absorption (in magnitudes) and wavelength.

→ interstellar; → reddening; → curve.

An apparent twinkling of the signals from distant point-like radio sources (pulsars). It is due to turbulence, i.e. fluctuations in the electron density of the interstellar ionized gas, through which the signals have passed on their way to Earth.

→ interstellar; → scintillation.

1) A minute gap between the adjacent parts of a body or objects close together.
2) In a crystal lattice, the empty space between adjacent atoms. The interstices are of two types: Tetrahedral-interstices and Octahedral-interstices. Also called → interstitial site.

From L. interstitium "space between; interval," from intersistere, from → inter- "between," + stem of stare "to stand," cognate with Pers. istâdan, → stand

Andarjâ, literally "a place between," from andar "between," → inter-, + jâ, → place.

1) Pertaining to, situated in, or forming → interstices.
2) → interstitial atom.

→ interstice; → -al.

In a → crystal, an imperfection caused by the presence of an extra atom that occupies a place outside the normal → lattice position. It may be the same type of atom as the others (self interstitial) or an → impurity atom.

→ interstitial; → atom.

A network of fluid-filled spaces in the body's connective tissues all over the body. It lies below the skin's surface and surrounds arteries, muscles, and the digestive and urinary tracts in a layer long thought to be dense connective tissue. Interstitium could be the largest organ in the human body

From L. interstitium, → interstice.

Andarjâyân, from andarjâ, → interstice, + euphonic sound -y-, + relation suffix -ân.

Describing something that involves mutual relations between systems.

→ inter-; → system.

A → radiationless relaxation process in which a molecule in some excited → electronic state converts to a state of different spin → multiplicity. Intersystem crossing is analogous to → internal conversion.

→ intersystem; → crossing.

In spectroscopy, same as → semi-forbidden line.

→ inter-; → system.

1) Math.: A portion of a real line (i.e. a line with a fixed scale so that every real number corresponds to a unique point on the line) between two designated endpoints. → span.
2) Music: Difference in pitch between two tones of a scale.

From O.Fr. intervalle, from L.L. intervallum, originally "space between two palisades or ramparts," from → inter- "between" + vallum "rampart."

Andarvâr, literally "between walls," from andar-→ inter- + vâr "wall," as in divâr "wall" (originally "fortress wall," from *dida-vāra-), variant bâru "wall, rampart, fortification; fort; tower;" Mid.Pers. bâr, var "enclosure, defences, fortress;" Av. var- "castle."

1) To occur or be between two things.
2) To occur or happen between other events or periods.
3) Law: To interpose and become a party to a suit pending between other parties (Dictionary.com).

Back-formation from → intervention.

Occurring or falling between events or points.

→ intervene; → -ing.

A cloud of dust particles that happens to lie on the → line of sight between the → observer and the → object.

→ intervening; → dust.