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

Stars and Stripe


SN1006In 1006 A.D., observers from Africa to Europe to the Far East recorded the arrival of light from what is now called SN 1006, a tremendous supernova explosion of a white dwarf star nearly 7,000 light-years away. The supernova was probably the brightest star ever seen in recorded times. It surpassed Venus in the night time sky, only being outshone by the moon. It was visible during the day for weeks, and remained visible to the naked eye for at least two and a half years before fading away.

About 50 years ago, radio astronomers detected a nearly circular ring of material at the recorded position of the supernova. The ring was almost the same angular diameter as the full moon. The size of the remnant implied that the blast wave from the supernova had expanded at nearly 20 million miles per hour over the nearly 1,000 years since the explosion occurred.

Today, we know that SN 1006 has a diameter of nearly 60 light-years, and is still expanding at roughly 6 million miles per hour. Even at that speed, however, it takes observations years apart to detect significant outward motion of the shock wave. This Hubble image of a delicate ribbon of gas shows a very thin section of the supernova remnant. The location of the 1006 explosion is well out of the farme to the lower left. The shock wave is moving to the upper right.

Image Credit: NASA

The Backward Galaxy


backward galaxyThe Backward Galaxy (aka NGC4622) lies 111 million light years away in the constellation Centaurus. NGC 4622 is an example of a galaxy with leading spiral arms. In most spiral galaxies, the spiral arms trail; that is, the tips of the spiral arms are winding away from the center of the galaxy in the direction of the disk’s orbital rotation. In NGC4622, however, the outer arms are leading spiral arms; the tips of the spiral arms point towards the direction of disk rotation. This may be the result of a gravitational interaction between NGC 4622 and another galaxy or the result of a merger between NGC 4622 and a smaller object.

Image Credit: NASA

The Cartwheel Galaxy


Cartwheel GalaxyThe Cartwheel Galaxy (also known as ESO 350-40) is a lenticular and ring galaxy about 500 million light-years away in the constellation Sculptor. The ring resulted from a collision between two galaxies that would have been observed for the first time on Earth at the beginning of the Jurassic Period 200 million years ago. What we see today took 200 million years to develop, based on rate analysis of expanding gases.

Image Credit: NASA

Closing In On The Comet


Rosetta 20140924This is a four-image NAVCAM mosaic taken by the Rosetta spacecraft on 24 September from a distance of 28.5 km from the centre of comet 67P/C-G. The images are processed to remove some striping and fixed noise patterns.

As the spacecraft moves closer to the comet, it is harder to create accurate mosaics because of combined effect of the comet rotation between the first and last images taken in the sequence (about 10 degrees over 20 minutes), and the fact that the spacecraft has been moving (up to a couple of km).

Image Credit: ESA

MAVEN’s First Look


iuvs-final-image-annotatedMAVEN is the first spacecraft dedicated to exploring the tenuous upper atmosphere of Mars, and it has made its first observations of the extended upper atmosphere surrounding Mars. The Imaging Ultraviolet Spectrograph (IUVS) instrument obtained these false-color images eight hours after Mars orbit insertion.

The images show the planet from an altitude of 36,500 km in three ultraviolet wavelength bands. Data represented in blue shows UV light from the sun scattered by atomic hydrogen gas in an extended cloud that extends thousands of kilometers above the planet’s surface.  Green shows a different wavelength of ultraviolet light that is primarily sunlight reflected by atomic oxygen. Red shows ultraviolet sunlight reflected from the planet’s surface. The bright spot in the lower right is light reflected either from polar ice or clouds.

The oxygen gas is held close to the planet by Mars’ gravity, while lighter hydrogen gas is present to higher altitudes and extends past the edges of the image. These gases derive from the breakdown of water and carbon dioxide in Mars’ atmosphere. During its one-Earth-year-long primary science mission, MAVEN observations like these will be used to determine the loss rate of hydrogen and oxygen from the Martian atmosphere.  Those observations should allow an reasonable estimate of the amount of water that has escaped from Mars over time.

Image Credit: NASA