English (UK)
Nights of October 30th and 31st are the best opportunity for studying this asteroid, which characteristics points that it could be an extinct comet.
The asteroid, with 400 meters wide, will be at about 480.000 km from Earth at its closest approach.
The near earth object, named as 2015TB145, informally designate as "Halloween asteroid" or "The great Halloween pumpkin", will be today studied from the Calar Alto Observatory by an international group of scientists, coordinated from the Instituto de Astrofísica de Andalucía (IAA-CSIC).
The interest of this object for the scientific community firstly lies in its cataloging as NEO (Near Earth Object), as its closest approach will be of about 480.000 km, -1.3 times the distance between Earth and Moon; and secondly, due to the fact that its orbital characteristics points that this could be an extinct comet.
"This object seems to have a relative big size for the NEOs that habitually approach this distance from the Earth, and constitutes an excellent opportunity for us to study this kind of objects", René Duffard, researcher from IAA-CSIC, who participates in this observation campaign from Calar Alto, points.
"NEOs, and particularly, the potentially dangerous, as this one, have to be studied deeply, not only because we can learn a lot about formation and evolution of our Solar System, but also because we must know their physic properties as better as possible, so in the future we will be able to divert and avoid collisions with them", the researcher adds.
HALF ASTEROID, HALF COMET
This object, found last 10th of October, also presents the peculiarity of showing characteristics of both asteroids and comets. While asteroids normally have circular orbits around the sun, comets follow very elliptic orbits, so most of the time are in distant regions of the Solar System. "2015TB145 has a very elliptic orbit, and until it was located near its perihelion, or closest approach to the sun, we were not able to detect it", Jesús Aceituno, Calar Alto Observatory Deputy Director, points.
But, although its orbit seems like the one for the comets, the look of 2015TB145 shown on the images, corresponds to the asteroids ones, as it has neither gaseous envelope (the cometary coma) nor tail. "In this sense, some researchers think that it could be an extinct comet, due to the fact that it has exhausted its ice, or the volatile material, during its successive sun approaches. And due to the fact that the ice sublimation does not occur, the comas or tails we are used to, are not generated. " José Luis Ortiz, researcher from IAA-CSIC who is involved in the study, says.
Shortly after its discovery, some researchers were quick to communicate to the International Astronomical Union, through their circulars, the possibility that "The Great Halloween pumpkin" could produce a meteor shower, in the same way as some comets produce well known meteor showers, as the "tears of San Lorenzo" or "Perseids". According to other researchers, this possibility seems to be remote, because of the apparently inactivity of 2015TB145 nucleus, and due to other factors.
From Calar Alto, and together with other world observations with different kind of instruments, the international researchers group will study the size, shape and thermal properties of the object's surface, as well as some characteristics of its internal structure, in order to try to determine, for instance, if it is a monolithic object, or what is known as a "pile of rubble". This has a big importance towards the divert or destruction strategies in the future. At the same time, Calar Alto with the special instrumentation the Observatory has for this purpose, will pay special attention to the possible meteor shower associated to this object.
The German-Spanish Calar Alto Observatory is located at Sierra de los Filabres, north of Almería (Andalucía, Spain). It is jointly operated by the Instituto Max Planck de Astronomía in Heidelberg, Germany, and the Instituto de Astrofísica de Andalucía (CSIC) in Granada, Spain. Calar Alto has three telescopes with apertures of 1.23m, 2.2m and 3.5m. A 1.5m aperture telescope, also located at the mountain, is operated under control of the Observatorio de Madrid.
COMMUNICATION – CALAR ALTO OBSERVATORY