Monday, 24 April 2017

Recalculating the nature of the planets of thr TRAPPIST-1 system, using data from the Kepler Space Telescope.

M-type Stars (Red Dwarfs) are the most abundant type of stars in the galaxy, and are both smaller and longer lived than other types of stars. A number of recent studies have shown that many such stars are home to planetary systems, making them of great interest to planetary scientists. One recent discovery of particular not is the TRAPIST-1 system (formerly 2MASS J23062928-0502285), comprising a Red Dwarf Star (TRAPPIST-1A) 39.5 light years from Earth in the constellation of Aquarius, that has only 0.08 times the mass of the Sun, but which is surrounded by a system of six known planets (TRAPPIST-1 b, c, d, e, f, and g).

The system discovered in 2016 by the 2MASS (Two Micron All-Sky Survey) project, which combined data from telescopes at the Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona and the Cerro Tololo Inter-American Observatory in Chile, and all six planets estimated to be of approximately Earth-mass, generating  great deal of interest in the system, and therefore a desire on behalf of planetary scientists to gather further data on the system.

In a paper published on the arXiv database at Cornell University Library on 13 April 2017, Songhu Wang of the Department of Astronomy at Yale University, Dong-Hong Wu of the School of Astronomy and Space Science and Key Laboratory of Modern Astronomy and Astrophysics at Nanjing University, Thomas Barclay of the NASA Goddard Space Flight Center, and the University of Maryland, and Gregory Laughlin also of the Department of Astronomy at Yale University describe the results of a study of the TRAPPIST-1 system using data from the Kepler Space Telescope.

The Kepler Space Telescope was launched in March 2009, and was trained on a single area of sky, the Kepler Deep Field until May 2013, when the spacecraft malfunctioned and begun to spin on its axis. This did not however prevent the craft from gathering new data, despite the inability of astronomers to choose the telescope's targets. Between 15 December 2016 and 4 March 2017 the TRAPPIST-1 system fell within Kepler's field of view, enabling the telescope to gather data on this system. 

Wang et al. took the Kepler observation data for the TRAPPIST-1 system and analysed the light curved produced by the system's planets passing in front of the star, in order to produce a new model of the TRAPPIST-1 system.

Based upon this data Wang et al. calculate that the innermost planet, TRAPPIST-1b, has an orbital period of 1.5 days, and orbits the star at an average distance of 0.011 AU, i.e. 1.1% of the distance at which the Earth orbits the Sun. They further calculate that planet has a mass 0.79 times that of the Earth, and a radius 1.086 times that of the Earth. 

The second planet, TRAPPIST-1c, is calculated to have an orbital period of 2.4 days and orbit at an distance of 0.015 AU. This planet is estimated to have a mass 1.63 times that of the Earth, and a radius 1.056 times the Earth's.

The third planet, TRAPPIST-1d, is calculated to have an orbital period of 4.0 days and orbit at an distance of 0.021 AU. This planet is estimated to have a mass 0.33 times that of the Earth, and a radius 0.722 times the Earth's.

 Orbits of the Trappist-1 planetary system. The yellow lines are 1000 planetary orbits drawn randomly from the converged Markov Chain in TTV dynamical ts. The blue points correspond to the location of the planets at the K2 initial epoch 2,457,738.3654. Further photometric transit follow-up is urgently needed to attain a precise understanding of the Trappist-1 system. Wang et al. (2017).

The fourth planet, TRAPPIST-1e, is calculated to have an orbital period of 6.1 days and orbit at an distance of 0.028 AU. This planet is estimated to have a mass 0.24 times that of the Earth, and a radius 0.918 times the Earth's.
The fifth planet, TRAPPIST-1f, is calculated to have an orbital period of 12.4 days and orbit at an distance of 0.045 AU. This planet is estimated to have a mass 0.36 times that of the Earth, and a radius 1.045 times the Earth's.
The sixth planet, TRAPPIST-1f, is calculated to have an orbital period of 6.1 days and orbit at an distance of 0.028 AU. This planet is estimated to have a mass 0.57 times that of the Earth, and a radius 1.127 times the Earth's.
See also...
http://sciencythoughts.blogspot.co.uk/2016/09/faint-companions-discovered-to-two.htmlhttp://sciencythoughts.blogspot.co.uk/2015/12/detecting-debirs-disks-around-small.html
 

http://sciencythoughts.blogspot.co.uk/2015/02/when-schotzs-star-passed-through-solar.htmlhttp://sciencythoughts.blogspot.co.uk/2015/05/kepler-432-red-giant-star-with-at-least.html




http://sciencythoughts.blogspot.co.uk/2014/04/kepler-186f-earth-sized-planet-in.html
http://sciencythoughts.blogspot.co.uk/2015/02/a-compact-planetary-system-around.html



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Sunday, 23 April 2017

Magnitude 5.3 Earthquake off the northeast coast of Mindanao Island, The Philippines.

The United States Geological Survey recorded a Magnitude 5.3 Earthquake at a depth of 62.8 km about 12 km off the coast of the resort of Burgos in Agusan del Sur Province on northern Mindanao Island, Philippines, slightly before 9.20 am local time (slightly before 1.20 am GMT) on Sunday 23 April 2017. There are no reports of any casualties this event, though some minor damage has been reported in the municipality of Tago.

 The approximate location of the 23 April 2017 Mindanao Earthquake. Google.

The geology of the central Philippines is Complex. The west of Mindanao Island is located on the Banda (or Sunda) Microplate, and the east on the Philippine Plate, which is being subducted beneath the Sunda (or Banda) Microplate along the central part of the island. Immediately to the east of the Island the Pacific Plate is being subducted along the Philippine Trench, and passes beneath eastern Mindanao as it sinks into the Earth. This is not a smooth process, an the plates constantly stick together then break apart again as the pressure builds up, resulting in Earthquakes.

 Subduction beneath the Philippines. Yves Descatoire/Singapore Earth Observatory.

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organisation Earthquake Report is interested in hearing from people who may have felt this event; if you felt this quake then you can report it to Earthquake Report here.
 
See also...
 
http://sciencythoughts.blogspot.co.uk/2017/02/magnitude-65-earthquake-off-north-coast.htmlhttp://sciencythoughts.blogspot.co.uk/2016/09/magnitude-59-earthquake-on-mindanao.html
http://sciencythoughts.blogspot.co.uk/2016/08/magnitude-54-earthquake-beneath.htmlhttp://sciencythoughts.blogspot.co.uk/2014/06/magnitude-50-earthquake-in-hinatuan.html
http://sciencythoughts.blogspot.co.uk/2014/01/magnitude-48-earthquake-on-mindanao.htmlhttp://sciencythoughts.blogspot.co.uk/2014/01/at-least-nine-dead-following-flash.html
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Guiaphaenops deuvei: A new species of cave-dwellin Ground Beetle from Guangxi Province.

Ground Beetles (Carabidae) are large, usually carnivorous Beetles, abundant across much of the globe. They are able to defend themselves by secreting noxious or caustic chemicals from glands on their abdomens (Bombardier Beetles are Carabids). Members of the genus Guiaphaenops specialist cave-dwellers known only from the limestone caves of Lingyun County in northwestern Guangxi Province, China. They show specialisations to cave life found in many animal groups, including the loss of their eyes and pigment.

In a paper published in the journal ZooKeys on 20 April 2017, Bin Feng of the Forestry Department of Guangxi Zhuang Autonomous Region and the Department of Entomology at South China Agricultural University, Guofu Wei of the Administrative Bureau of Huangjiang World Natural Heritage and Mingyi Tian, also of the Department of Entomology at South China Agricultural University, describe a new species of Guiaphaenops from a limestone cave near Yangli in Lingyun County.

The new species is named Guiaphaenops deuvei, in hnour of French entomologist Thierry Deuve of the National Museum of Natural History in Paris (who first described the genus Guiaphaenops) for his work on the Ground Beetles of China. The species is described from a single male specimen found on the floor of the cave. It is 7 mm in length, and yellowish in colour.

Guiaphaenops deuvei, male specimen. Feng et al. (2017).

See also...

http://sciencythoughts.blogspot.co.uk/2014/05/six-new-species-of-ground-beetles-from.htmlhttp://sciencythoughts.blogspot.co.uk/2014/04/a-new-species-of-ground-beetle-from.html
http://sciencythoughts.blogspot.co.uk/2014/03/a-new-species-of-cave-dwelling-ground.htmlhttp://sciencythoughts.blogspot.co.uk/2014/01/a-new-species-of-ground-beetle-from.html
http://sciencythoughts.blogspot.co.uk/2013/06/a-blind-cave-dwelling-ground-beetle.htmlhttp://sciencythoughts.blogspot.co.uk/2012/12/two-new-species-of-ground-beetle-from.html
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Asteroid 2017 HG1 passes the Earth.

Asteroid 2017 HG1 passed by the Earth at a distance of  1 078 000 km (2.80 times the average distance between the Earth and the Moon, 0.72% of the average distance between the Earth and the Sun), slightly before 10.00 pm GMT on Wednesday 16 April 2017. There was no danger of the asteroid hitting us, though had it done so it would have presented no threat. 2017 HG1 has an estimated equivalent diameter of 5-19 m (i.e. it is estimated that a spherical object with the same volume would be 5-19 m in diameter), and an object of this size would be expected to explode in an airburst (an explosion caused by superheating from friction with the Earth's atmosphere, which is greater than that caused by simply falling, due to the orbital momentum of the asteroid) in the atmosphere between 38 and 23 km above the ground, with only fragmentary material reaching the Earth's surface.

The calculated orbit of 2017 HG1. Minor Planet Center.
 
2017 HG1 was discovered on 19 April 2017 (two days after of its closest approach to the Earth) by the University of Arizona's Mt. Lemmon Survey at the Steward Observatory on Mount Lemmon in the Catalina Mountains north of Tucson. The designation 2017 HG1 implies that the asteroid was the 32nd object (object G1) discovered in the second second of April 2017 (period 2017 H). 

2017 HG1 has a 260 day orbital period, with an elliptical orbit tilted at an angle of 7.09° to the plain of the Solar System which takes in to 0.56 AU from the Sun (56% of the distance at which the Earth orbits the Sun; inside the orbit of the planet Venus) and out to 1.03 AU (3% further away from the Sun than the Earth). This means that close encounters between the asteroid and Earth are fairly common, with the last thought to have happened in November 2014 and the next predicted in November 2019. 2017 HG1 also has frequent close encounters with the planet Venus, with the last though to have occurred in October 2012 next predicted for March 2021. Although it does cross the Earth's orbit and is briefly further from the Sun on each cycle, 2017 HG1 spends most of its time closer to the Sun than we are, and is therefore classified as an Aten Group Asteroid.
 
See also...
 
http://sciencythoughts.blogspot.co.uk/2017/04/the-lyrid-meteors.html
 
http://sciencythoughts.blogspot.co.uk/2017/04/asteroid-474231-2001-hz7-passes-earth.html
http://sciencythoughts.blogspot.co.uk/2017/04/fireball-over-southern-united-sates.html

http://sciencythoughts.blogspot.co.uk/2017/03/comet-41ptuttle-giacobini-kresak-passes.html
http://sciencythoughts.blogspot.co.uk/2017/04/asteroid-2015-tc25-passes-earth.html

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