October 24, 2014

Review: Dreams of Other Worlds by Chris Impey and Holly Henry

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Robotic space exploration has finally come of age. Recent successes, such as the pioneering landing via sky crane of the Mars Rover Curiosity by NASA have demonstrated a capability to triumph after a hard-won history often marked by failure.

This week’s review titled Dreams of Other Worlds: The Amazing Story of Unmanned Space Exploration by Chris Impey and Holly Henry chronicles the often overlooked history of robotic exploration of the solar system. Robots can go more cheaply and effectively where humans can’t, and don’t demand a return ticket. Out from Princeton University Press, Dreams of Other Worlds is a timely snapshot of the state of unmanned space exploration. [Read more...]

24.05.11: Throwing Exo-Planets into “The Blender.”

Artists’ conception of the Kepler-10 system. (Credit: NASA/Ames/JPL/CALTech).

On Monday, scientists unveiled a powerful new technique to quickly validate transiting exoplanets. The method, known as the “Blender,” combines data gathered for both the Kepler and Spitzer Space Telescopes in an effort to identify tiny transiting exo-worlds that would otherwise go unnoticed by ground-based instruments. [Read more...]

15.03.11: A Borderline Brown Dwarf.

A brown dwarf family portrait bracketed by our sun & Jupiter. (Artist’s conception: NASA/JPL/CalTech). 

Oh Be A Fine Girl/Guy Kiss Me Now… the mnemonic for stellar classification running from hottest to coldest has been long overdue overhaul, as brown dwarf classes L, T, and now Y have been placed on the cool end of the scale. And in the past month, a paper by Kevin Luhman and colleges at Pennsylvania State University have reported what may be the coolest brown dwarf known. [Read more...]

AstroEvent: When will Epsilon Aurigae Brighten?

  

Epsilon Aurigae: A finder chart. (Photo and graphics by the Author).

One of the strangest variable stars is worth watching this spring.  Back in 2009, we alerted viewers to monitor the curious variable Epsilon Aurigae. Once every 27.06 years, this star dips nearly a magnitude in brightness down to about +3.8, markedly discernable to the naked eye. This drop lasts for over a year before Epsilon Aurigae returns to its former self. This spring should witness such an occurrence. [Read more...]

11.05.10: Ancient Galaxy Mergers.

Hickson Compact Group 31. (Credit: NASA/HST/ESA/S. Gallagher/J. English).

Hickson Compact Group 31. (Credit: NASA/HST/ESA/S. Gallagher/J. English).

 

   Astronomers may have found a cosmological missing link in the realm of galactic evolution. The early universe was a crowded place; galaxy mergers must have been much more common in the primeval universe than they are today. But studying those early collisions has been problematic; the immense distances involved over time and space mean that resolving clusters and individual stars are out of the question. Now, a team from the University of Western Ontario led by Sara Gallagher has published a study of an object which may serve as a “living fossil” of those early times; Hickson Compact Group 31. A cluster of irregular galaxies “only” 166 million light years away in the constellation Eridanus, this merger has somehow escaped coalescence over 10 billion years of cosmic history to just begin merging. “Because HCG 31 is so nearby,” Gallagher notes, “we can indentify individual star clusters.” In fact, two main components of HCG 31 approach visual magnitude +13 and have been snared by amateur instruments. HCG 31 is approximately 75,000 light years in diameter, and will probably one day form one huge elliptical galaxy. To conduct this study, Gallagher utilized time and instruments that spanned the spectrum, from Hubble in visible light to Spitzer in infrared to Galex and Swift in the ultraviolet. It is amazing that astronomers now have such capabilities in their bag of tricks at their ready disposal!

02.05.10- Star-birth in the Early Universe.

(Credit: NASA/Hubble StS/Steward).

(Credit: NASA/Hubble StS/Steward).

A comparision of an ancient spiral galaxy in visible (left) and Infrared (right).

   Astronomers are shedding new light across the spectrum on an old cosmological mystery. It’s well documented that the rate of star formation today is much less than what it was early on in the history of the universe; what isn’t completely understood is why. Was there simply an abundance of star forming material available, or was the process of star formation more efficient? Either trend may have a huge significance as to how the current and future evolution of the universe plays out; stars such as our Sun are metal rich and formed as a result of the recycling of cosmic material from that first primeval generation of stars. Even non-fusion sustaining bodies such as the Earth, Sandra Bullock, and your IPad owe their elemental composition largely to those original stars.  Now, a team led by Michael Cooper of the University of Arizona’s Steward Observatory is tackling the dilemma from a fresh angle. The galaxies in question are about 4 billion years old; the universe is an estimated 13.7 billion years of age. In that tender young era, the rate of observed star formation was about 10 times what we see today. Traditional surveys have looked at larger, brighter, and more easily observable galaxies in the energetic throes of star formation. But is that the best approach? This method largely ignores the vast population of fainter, harder to spot galaxies. “It is a little like studying only individuals who are seven feet tall instead of those who fall in a more common range of height,” stated Cooper. Their unique approach has been to examine a selection of average galaxies culled from 50,000 objects to study across a range of wavelengths. Instruments called into action included the Hubble and Spitzer Space telescopes as well as an array of ground-based radio telescopes. Analysis across the spectrum shows that a much greater concentration of gas and dust was available to fuel star formation than what we see today; these galaxies also really light up in the radio and infrared, as pictured above… could we be looking at snapshots resembling our galaxies’ grandparents?

19.04.10- The Rise of WISE.

(Credit: NASA/JPL/CalTech/UCLA).

(Credit: NASA/JPL/CalTech/UCLA).

Spiral galaxy IC 342 shows its stuff in infrared!

NASA has a new orbiting infrared eye on the universe. WISE, the Wide-field Infrared Space Explorer, is now open for business, and returning some fairly cool images. Launched out of Vandenberg AFB on December 12th of last year, the telescope is now parked in a sun-synchronous orbit at an inclination of 97.5° degrees. This allows WISE to keep its solar panels in a sunward orientation, while the telescope itself looks off at right angles to the Sun. This will also allow it to image continuous swaths of the sky as it orbits the Earth. WISE sports a 16” 40cm gold-plated mirror (talk about tricked out!) optimized for IR work and will conduct an all-sky survey with an unprecedented resolution across its 47 arc minute field of view. A successor to the IRAS and Spitzer, which ran out of coolant last year, WISE has an on-board supply on frozen hydrogen that should sustain it for a 10 month mission. To perform its mission, WISE must be cooled to -430° F, or about 15 Kelvins. It will also narrow in on possible targets for the James Webb Space telescope to be launched in 2014. JWST is much touted as the “successor to Hubble” but will actually be optimized for work in the infrared as well. IR work is virtually impossible to do from ground based telescopes, due to the absorption of IR wavelengths by water vapor in our atmosphere. Already, WISE has discovered comets, Near Earth objects, and opened a new window on nebulae and star formation… more discoveries to come!

17.04.10- The Case of the Vanishing Moon: Solved.

(Credit: NASA/ESA/STScI/AURA)

(Credit: NASA/ESA/STScI/AURA)

The scale of the enormous and thin Phoebe Ring as recently imaged by Spitzer.

 

   Since its discovery by Giovanni Cassini in 1671, Saturn’s moon Iapetus has confounded astronomers. Even early on, observers knew something curious was going on with this far off moon; Iapetus varies in brightness between +10 & +12th magnitude as it orbits the ringed planet, nearly vanishing from sight for half its orbit! Late last year, NASA’s Cassini spacecraft and the Spitzer Space Infrared Telescope fingered the culprit; a tenuous outer ring of material now known as the Phoebe Ring that is raining down material on its surface. Like our own Moon, Iapetus is tidally locked in its 79 day orbit. As a consequence, the leading edge plows through this dusty stream of debris. This also causes sunlight to warm and sublimate icy material on the leading side, which streams and re-condenses on the trailing end. This nicely explains the sharply defined and complex boundary seen between the two hemispheres. Alas, no monolith as depicted in Clarke’s original 2001 novel adaptation. .. but perhaps a fine site one day for a cosmic ski resort!

24.10.09: Enceladan Seas?

The tortured surface of Enceladus as seen earlier last year from Cassini. (Credit: NASA/JPL).

The tortured surface of Enceladus as seen earlier last year from Cassini. (Credit: NASA/JPL).

Move over Europa ; yet another moon may harbor a subsurface sea. Saturn’s moon Enceladus has been inching its way up the charts as of late as a candidate world for extraterrestrial life. Barely 300 miles in diameter, the tiny world is repeatedly flexed by Saturn’s gravity and an increased orbital eccentricity pumped up by the nearby moon Dione. This has caused the tiger-striped surface seen by the Cassini space probe, a surface that shows evidence of repeated fissuring and freezing that almost certainly covers a liquid interior. In fact, Cassini has caught several of the geysers in the act during four recent flybys of the moon. One flyby was close enough that Cassini actually flew through a geyser plume! Activity on Enceladus is now known to almost exclusively contribute to Saturn’s E ring…and recently, a much broader ring system has been revealed by the Spitzer space telescope. Sodium chloride has also been detected in the E ring, presumably from the interior of Enceladus…clearly, the Saturnian system is a dynamic place warranting more scrutiny. Let’s hope that NASA approves Cassini’s seven year mission extension!

August 2009:News & Notes.

You can almost see Neil's foot print! (Credit: NASA/LRO).

You can almost see Neil's foot print! (Credit: NASA/LRO).

- The LRO Photographs the Apollo landing sites: Fans of this space may have noticed the racy lunar pics we ran a week back as part of our From Earth to the Moon review. The Lunar Reconnaissance Orbiter did indeed snap pics of the famous Apollo landing sites last month. These clearly show the hardware left at multiple sites, as well as the base(s) of the Lunar Lander ascent stages, complete with shadow. You can even see the astronaut’s foot trails in the lunar dust! And the LRO hasn’t even entered its cruising orbit yet… expect more great pics to come! [Read more...]