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| The Grandma & Joseph visit L'Observatori de l'Ebre |
Today, The Grandma has visited Roquetes, a beautiful town in El Baix Ebre County, in Tarragona.
The Grandma has visited accompanied by Joseph de Ca'th Lon, her closer friend. They have arrived to visit L'Observatori de l'Ebre, the astronomical centre that is sited there.
Joseph has explained lots of things to The Grandma. They have been talking about planets and paying a lot of attention to the first planet orbiting another sun, 51 Pegasi b that was discovered on a day like today in 1995.
The Observatori de l’Ebre (OE) is a Research Institute founded by the Society of Jesus in 1904 to study Sun-Earth relationships. Over the years it has excelled in the study of earth currents, atmospheric electricity, seismology, solar and geomagnetic activity, and the terrestrial Ionosphere, and continues to do so today in the latter two fields.
The OE is governed by a Non Profit Foundation. At present it forms part of the Ramon Llull University (URL) as a University Institute. It is located in Roquetes, in El Baix Ebre, Tarragona. The town is located on the eastern side of the Ports de Tortosa-Beseit. A great part of its municipal territory is located in the Els Ports Natural Park, including many important peaks of the Ports de Tortosa-Beseit Range, such as Mont Caro and Castell de l'Airosa.
51 Pegasi b, abbreviated 51 Peg b, unofficially dubbed Bellerophon, later formally named Dimidium, is an extrasolar planet approximately 50 light-years away in the constellation of Pegasus. It was the first exoplanet to be discovered orbiting a main-sequence star, the Sun-like 51 Pegasi, and marked a breakthrough in astronomical research. It is the prototype for a class of planets called hot Jupiters. In 2017, traces of water were discovered in the planet's atmosphere.
51 Pegasi is the Flamsteed designation of the host star. The planet was originally designated 51 Pegasi b by Michel Mayor and Didier Queloz, who discovered the planet on December 1995. The following year it was unofficially dubbed Bellerophon by astronomer Geoffrey Marcy, who followed the convention of naming planets after Greek and Roman mythological figures. Bellerophon was a figure from Greek mythology who rode the winged horse Pegasus.
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| 51 Pegasi b |
In December 2015, the IAU announced the winning name for this planet was Dimidium. The name was submitted by the Astronomische Gesellschaft Luzern (German for Astronomical Society of Lucerne), Switzerland. Dimidium is Latin for half, referring to the planet's mass of at least half the mass of Jupiter.
The exoplanet's discovery was announced on October 6, 1995, by Michel Mayor and Didier Queloz of the University of Geneva in the journal Nature. They used the radial velocity method with the ELODIE spectrograph on the Observatoire de Haute-Provence telescope in France and made world headlines with their announcement.
More information: Exoplanets NASA
The planet was discovered using a sensitive spectroscope that could detect the slight and regular velocity changes in the star's spectral lines of around 70 metres per second. These changes are caused by the planet's gravitational effects from just 7 million kilometres' distance from the star.
Within a week of the announcement, the planet was confirmed by another team using the Lick Observatory in California.
This was the first discovery of an exoplanet orbiting a Sun-like star, the first exoplanet discovery was made by Aleksander Wolszczan in 1992, around pulsar PSR 1257. It marked a turning point and forced astronomers to accept that giant planets could exist in short-period orbits.
Once astronomers realized that it was worth looking for giant planets with the currently available technology, much more telescope time was devoted to radial velocity planet searches, and hence many more exoplanets in the Sun's neighborhood were discovered.
More information: Earth Sky
After its discovery, many teams confirmed the planet's existence and obtained more observations of its properties. It was discovered that the planet orbits the star in around 4 days. It is much closer to it than Mercury is to the Sun, moves at an orbital speed of 136 km/s, yet has a minimum mass about half that of Jupiter, about 150 times that of the Earth.
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| Earth & 51 Pegasi b & Jupiter Comparison |
At the time, the presence of a huge world so close to its star was not compatible with theories of planet formation and was considered an anomaly. However, since then, numerous other hot Jupiters have been discovered and astronomers are revising their theories of planet formation to account for them by studying orbital migration.
Assuming the planet is perfectly grey with no greenhouse or tidal effects, and a Bond albedo of 0.1, the temperature would be approximately 1000°. This is between the predicted temperatures of HD 189733 b and HD 209458 b (1180–1392 K), before they were measured.
In the report of the discovery, it was initially speculated that 51 Pegasi b was the stripped core of a brown dwarf of a decomposed star and was therefore composed of heavy elements, but it is now believed to be a gas giant. It is sufficiently massive that its thick atmosphere is not blown away by the star's solar wind.
More information: The Atlantic
51 Pegasi b probably has a greater radius than that of Jupiter despite its lower mass. This is because its superheated atmosphere must be puffed up into a thick but tenuous layer surrounding it. Beneath this, the gases that make up the planet would be so hot that the planet would glow red. Clouds of silicates may exist in the atmosphere.
The planet is tidally locked to its star, always presenting the same face to it. The planet, with Upsilon Andromedae b, was deemed a candidate for direct imaging by Planetpol. It is also a candidate for near-infrared characterisation.... with the VLTI Spectro-Imager.
The first ever direct detection of the visible light spectrum reflected from an exoplanet has been made by an international team of astronomers on 51 Pegasi b. The astronomers studied light from 51 Pegasi b using the High Accuracy Radial velocity Planet Searcher (HARPS) instrument at the European Southern Observatory's La Silla Observatory in Chile.
More information: Solstation
It's been said that astronomy is a humbling and,
I might add, a character-building experience.
Carl Sagan
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