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
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.
Fr.: plan de l'écliptique
The plane of Earth's orbit around the Sun.
Ecliptic Plane Input Catalogue (EPIC)
kâtâlog-e dardâdâ-e hâmon-e hurpehi
Fr.: catalogue d'entrée du plan de l'écliptique
Fr.: plan équatorial
Fr.: plan équatorial
The plane containing a celestial object's equator.
Same as → extrasolar planet.
Of, relating to, or resembling an → exoplanet or exoplanets.
Fr.: système exoplanétaire
Fr.: planète extrasolaire
Fr.: plan focal
A plane at right angles to the principal axis of a lens or mirror on which the best image is formed.
Fr.: plan galactique
sayyâre-ye qulpeykar (#)
Fr.: planète géante
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).
Fr.: plan d'image
The plane in which is formed an image produced by an → optical system.
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
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.