Columna de Nicolás Luco:

Nos entretuvimos mucho la semana pasada con los adelantos presentados en Las Vegas: autos autónomos, teléfonos flexibles, videojuegos con retroalimentación táctil, un dron que sobrevuela a una persona y la sigue porque está programado para reconocer su rostro...

Pero también aparecieron grandes descubrimientos astronómicos.

Uno de ellos ocurrió en el Núcleo de Estudios Protoplanetarios (MAD) de la Universidad de Chile, que dirige Simón Casassus.

Sebastián Marino, otro joven del MAD, candidato a magíster en astronomía, fue quien en realidad descubrió una rareza en unos discos protoplanetarios.

¿Discos protoplanetarios...?

Los sistemas planetarios, como nuestro sistema solar, se forman a partir de discos de gas y polvo que rodean estrellas recién nacidas. Esos son los discos protoplanetarios (porque de ahí saldrán los planetas).

Los astrónomos los buscan en el universo, los enfocan con sus telescopios y los estudian porque así descubren cómo se forman los planetas. Por mucho que el cielo que en vacaciones aprovechamos de observar parezca idéntico al que acompañó a nuestros antepasados, está claro que no es así. Arriba pasan cosas.

(De hecho, está pasando por sobre nuestras cabezas, al oeste de las patitas de la constelación de Orión, la de las Tres Marías, el verde cometa Lovejoy. Anteayer fue su momento más cercano. Como para irse al norte esta semana para asegurarse de verlo en su verdor, ojalá con binoculares; entre las 22:00 y las 00:45 horas. Es nuestra única oportunidad: la próxima vez pasará en el año 13515.)

Bueno, volvamos a Sebastián Marino, que estuvo observando los cambios en la vecina joven estrella HD 142527, embarazada de planetas. La nube de gas y polvo a su alrededor daría origen a sistemas solares como el nuestro, con sus mundos.

Como siempre, Marino pensaba que esa nube, ese disco protoplanetario, era perfectamente plano, como es nuestro sistema solar. Alrededor de nuestra estrella, el Sol, todos los planetas giran como si estuvieran sobre un plato.

Pero él vio algo inesperado. Sombras en el polvo del disco. Sacó su calculadora y comprobó que eso que parecía un disco se dividía en dos: un disco externo, pesado y otro interno, leve. Pero lo más interesante es que el disco interno está ladeado, en un ángulo de 70º, en relación al disco externo. ¡Cosa más rara!

Imagino qué ocurriría si alrededor de nuestro Sol orbitaran planetas en dos planos. Opino que no podríamos subsistir. Desde luego, nuestra órbita terrestre sufriría todo tipo de malestares atraída por la masa de los planetas del otro plano.

¿Qué irá a ocurrir con la bella embarazada, la joven HD 142527? ¿Dará a luz a dos sistemas planetarios pegados como siameses?

Mejor esperemos que Marino culmine su magíster y llegue a una conclusión más o menos definitiva. Difícil, porque aquello que está observando a través de sus telescopios mide lo que una millonésima parte de la Luna.

Protoplanetary Disk around HD 142527

Jan 20, 2014 by Sci-News.com

By using the Atacama Large Millimeter/submillimeter Array (ALMA), Japanese astronomers have spotted strong evidence of a massive planet-forming disk around a young star known as HD 142527.

This image shows a dusty protoplanetary disk around HD142527. The dust and gas are shown in red and green, respectively; near-infrared image taken by the NAOJ Subaru Telescope is shown in blue. The image clearly shows that the dust is concentrated in the upper part of the disk. Image credit: ALMA / ESO / NAOJ / NRAO / Fukagawa et al.

HD 142527 lies in the constellation Lupus at a distance of about 457 light-years from Earth.

The astronomers have used ALMA to detect the submillimeter emission from the dust ring around this baby star. The emission has a non-uniform distribution and the northern side is 30 times brighter than the faint southern side, according to the team.

Recent near-infrared observations with the NAOJ Subaru Telescope revealed that protoplanetary disks have structures that are far more complex than astronomers expected. Spiral or gap structures are thought to be associated with hidden planets in the disk.

However, it is impossible to measure the amount of dust and gas in the densest part of the disk by near-infrared observations. Since near-infrared light is easily absorbed or scattered by a large amount of dust, it isn’t suitable for observing the innermost part of the dense region of the disk. Then, the key to the solution will be millimeter and submillimeter wave.

The new image of HD 142527, which was taken with ALMA, shows that cosmic dust is circling around the star in a form of asymmetric ring.

By measuring the density of dust in the densest part of the ring, the astronomers found that it is highly possible that Jupiter-like giant gaseous exoplanets or Earth-like rocky planets are now being formed in that region. This region is far from the central star, about 5 times larger than the distance between the Sun and the Neptune.

“We are very surprised at the brightness of the northern side,” said Dr Misato Fukagawa of Osaka University, who is the lead author of the paper appearing in the Publications of the Astronomical Society of Japan (full paper in .pdf /arXiv.org version).

“The brightest part in submillimeter wave is located far from the central star, and the distance is comparable to five times the distance between the Sun and the Neptune. I have never seen such a bright knot in such a distant position.”

“This strong submillimeter emission can be interpreted as an indication that large amount of material is accumulated in this position. When a sufficient amount of material is accumulated, planets or comets can be formed here. To investigate this possibility, we measured the amount of material.”

In calculating the amount of material based on the submillimeter emission strength, the temperature of the material is an important parameter. The scientists estimated the temperature in the dense region from the observations of isotopomers of carbon monoxide and reached two possibilities – formation of gaseous giant planet or rocky planet.

If the abundance of dust and gas is comparable to that in typical environment in the Universe, the dense region is massive enough to attract large amount of gas due to the self-gravity and form giant gaseous planets several times more massive than Jupiter. Although this is similar to the formation process of stars in cosmic clouds, it was the first time that the possibility of such a planet formation process was directly suggested by observations of protoplanetary disks.

The other possibility is the formation of dust trap in which the abundance of dust is exceptionally higher than the other part of the disk. If the dust trap is formed in the disk, earth-like rocky planets, small bodies such as comets, or cores of gaseous planets may be formed.

In both cases, it is highly possible that exoplanets are being formed in the dense part of the disk around HD142527.

The astronomers plan further observations of HD142527 with ALMA for closer investigation, as well as other protoplanetary disks to have a comprehensive understanding of the planet formation in general.