born-again planetary nebula
miq-e sayâreyi-ye bâzzâd
Fr.: nébuleuse planétaire recyclée
A → planetary nebula which is thought to have experienced a → very late thermal pulse (VLTP) when the central star (→ CSPN) was on the → white dwarf cooling track. The VLTP event occurs when the thermonuclear → hydrogen shell burning has built up a → shell of helium with the critical mass to ignite its → fusion into carbon and oxygen (→ helium shell burning). Since the → white dwarf envelope is shallow, the increase of pressure from this last helium shell flash leads to the ejection of newly processed material inside the old planetary nebula, leaving the stellar core intact. As the stellar envelope expands, its → effective temperature decreases and the star goes back to the → asymptotic giant branch (AGB) region in the → H-R diagram. The subsequent stellar evolution is fast and will return the star back to the → Post-AGB track in the H-R diagram: the envelope of the star contracts, its effective temperature and ionizing photon flux increase, and a new fast stellar wind develops (see, e.g. J. A. Toalá et al. 2015, ApJ 799, 67).
compact planetary nebula B[e] star (cPNB[e])
setâre-ye B[e]-ye miq-e sayyâre-yi-ye hampak
Fr.: étoile de nébuleuse planétaire compacte
A star whose spectrum shows striking similarities to → B[e] stars and is evolving into a → planetary nebula (→ preplanetary nebula).
sayyâre-ye kutulé (#)
Fr.: planète naine
A new category of → astronomical objects in the → solar system introduced in a resolution by the 26th General Assembly of the → International Astronomical Union (IAU) on August 24, 2006. The characterizing properties are as follows: 1) It is in orbit around the Sun; 2) It has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a → hydrostatic equilibrium (nearly round) shape; 3) It has not "cleared the neighbourhood" around its orbit; and 4) It is not a → satellite of a → planet, or other non-stellar body. The property 3 reclassified → Pluto from a planet to a dwarf planet because it has not cleared the neighborhood of its orbit (the → Kuiper Belt). The largest known dwarf planets are: → Eris, → Pluto, → Ceres, → Makemake, and → 2015 RR245.
Same as → extrasolar planet.
Of, relating to, or resembling an → exoplanet or exoplanets.
Fr.: système exoplanétaire
A → planetary system consisting of → exoplanets orbiting a star other than Sun.
→ exoplanetary; → system.
Fr.: transit d'exoplanète
The passage of an → exoplanet across the face its star.
→ exoplanetary; → transit.
The part of → astrophysics that searches and studies → extrasolar planets.
Fr.: planète extrasolaire
A planet which belongs to a star other than → Sun, and therefore does not belong to our → solar system; same as → exoplanet.
→ extrasolar; → planet.
sayyâre-ye qulpeykar (#)
Fr.: planète géante
A planet much more massive than Earth. The solar system has four giant planets: → Jupiter, → Saturn, → Uranus, and → Neptune.
High Accuracy Radial velocity Planet Searcher (HARPS)
A high-precision echelle spectrograph built for exoplanet findings and installed on the ESO's 3.6m telescope at La Silla Observatory in Chile. The first light was achieved in February 2003. HARPS has discovered dozens of exoplanets, making it the most successful planet finder behind the Kepler space observatory. HARPS can detect movements as small as 0.97 m s-1 (3.5 km h-1), with an effective precision of the order of 30 cm s-1, and a → resolving power of 120,000 (Mayor et al., 2003, ESO Messengar 114, 20).
→ high; → accuracy; → radial; → velocity; → planet; → search; → -er.
sayyâre-ye zirin (#)
Fr.: planète inférieure
A planet that orbits between the Earth and the Sun. Mercury and Venus are the only two inferior planets in the Solar System.
sayârehâ-ye daruni (#)
Fr.: planètes internes
The planets Mercury, Venus, Earth and Mars collectively. T hey are also known as the terrestrial planets.
interplanetary coronal mass ejections (ICME)
ešâneš-e andarsayyâreyi-ye jerm az tâj
Fr.: éjection de masse coronale interplanétaire
An → interplanetary manifestation of a → coronal mass ejection.
→ interplanetary; → coronal; → mass; → ejection.
Fr.: poussière interplanétaire
Particles of dust in the → interplanetary medium. They are left-overs from the beginning of the solar system or from other sources such as sublimating comets. Their existence was first deduced from observations of → zodiacal light.
→ interplanetary; → dust.
Fr.: gaz interplanétaire
Electrically charged particles of the solar wind and gas liberated from comets within the solar system.
→ interplanetary; → gas.
interplanetary magnetic field
meydân-e meqnâtisi-ye andarsayyârei
Fr.: champ magnétique interstellaire
The magnetic field that is carried along with the solar wind and fills the solar system space. It is wound into a spiral structure by the rotation of the Sun. At the Earth's distance from the Sun, it has a strength of about 5 x 10-5 gauss.
→ interplanetary; → magnetic; → field.
Fr.: matière interplanétaire
Material existing in the space between solar system planets. It includes interplanetary gas and dust.
→ interplanetary; → matter.
Fr.: milieu interplanétaire
The material contained in the → solar system in the space through which the planets travel. It consists of the smaller objects such as → asteroids, → comets, → meteorites and also a general pervading → interplanetary dust. Moreover a → plasma of charged particles streaming outward from the Sun in the form of the → solar wind contributes to the interplanetary medium.
→ interplanetary; → medium.
Fr.: espace interplanétaire
Same as → interplanetary medium.
→ interplanetary; → space.