A Dwarf and Its Debris


IDL TIFF fileThis visible-light image of the debris disk around the red dwarf star AU Microscopii hints that planets may be forming or might already exist within it. The disk glows in light reflected by tiny grains of dust resulting from  the collisions of asteroids and comets. This debris disk is more than 40 billion miles across. The star at the center is quite young, about 12 million years old. It is only 32 light-years from Earth which makes its disk the closest yet seen in reflected starlight. It is also the first disk imaged around an M-type red dwarf, the most common type of star in the stellar neighborhood around the Sun.The disk has been cleared of dust within about a billion miles of the star. Images taken by Hubble (including this one) confirm that the disk is warped and has small variations in density that may have been caused by the tugging of an unseen companion, perhaps a large planet. That would be consistent with presence of the inner gap as well.

This debris disk is unusual in that it is the only one known that appears bluer than the star it surrounds. This possibly could it having a greater proportion of very small grains of dust  than other such disks. Smaller grains scatter blue light better than red. The surplus of small grains may be caused by the star not being bright enough to blow away tiny particles. Brighter, hotter stars would produce sufficient radiation to push small dust grains out of the disk and out into interstellar space

Image Credit: NASA

Kaboom


On  23 April, 2014, the rising tide of X-rays from a superflare on red dwarf DG CVn triggered the Swift satellite’s Burst Alert Telescope (BAT). The satellite turned to observe the source in greater detail with its other instruments and notified astronomers around the globe that a powerful outburst was in progress.

BTW, my principal contribution to the Swift satellite was the design and testing of the ultra-quiet power regulation system for the sensor array in the BAT.

Video Credit: NASA

The Debris Disk Around a Red Dwarf Star


IDL TIFF fileThis visible-light image of the debris disk around the red dwarf star AU Microscopii hints that planets may be forming or might already exist within it. The disk glows in light reflected by tiny grains of dust resulting from  the collisions of asteroids and comets. This debris disk is more than 40 billion miles across. The star at the center is quite young, about 12 million years old. It is only 32 light-years from Earth which makes its disk the closest yet seen in reflected starlight. It is also the first disk imaged around an M-type red dwarf, the most common type of star in the stellar neighborhood around the Sun.The disk has been cleared of dust within about a billion miles of the star. Images taken by Hubble (including this one) confirm that the disk is warped and has small variations in density that may have been caused by the tugging of an unseen companion, perhaps a large planet. That would be consistent with presence of the inner gap as well.

This debris disk is unusual in that it is the only one known that appears bluer than the star it surrounds. This possibly could it having a greater proportion of very small grains of dust  than other such disks. Smaller grains scatter blue light better than red. The surplus of small grains may be caused by the star not being bright enough to blow away tiny particles. Brighter, hotter stars would produce sufficient radiation to push small dust grains out of the disk and out into interstellar space

Image Credit: NASA

A Red Dwarf


Proxima_CentauriA red dwarf is a small and relatively cool star on the main sequence. Red dwarfs range in mass from about 7 to roughly 50 percent the mass of the Sun and have surface temperatures of less than 4,000 K. They are by far the most common type of star in the Milky Way, but because they are dim in the visible light spectrum, individual red dwarfs cannot easily be observed. Indeed, not a single one can be seen by the naked eye from Earth. According to some estimates, three-fourths of the stars in the Milky Way are red dwarfs—as is our nearest neighbor.

Proxima Centauri  is a red dwarf about 4.24 light-years from the Sun and is the nearest known star to the Sun. Its distance to the second- and third-nearest stars, which form the bright binary Alpha Centauri, is sufficiently close (about .24 light-year) that it is very likely part of a triple star system with Alpha Centauri A and B, but its orbital period in that system may be greater than 500,000 years.

Image Credit: NASA

A Mega Flare from a Mini Star


At 2107 UTC on  23 April, the rising tide of X-rays from a superflare on red dwarf DG CVn triggered Swift‘s Burst Alert Telescope (BAT). The satellite turned to observe the source in greater detail with its other instruments and notified astronomers around the globe that a powerful outburst was in progress.

BTW, my principal contribution to the Swift satellite was the design and testing of the ultra-quiet power regulation system for the sensor array in the BAT.

Video Credit: NASA