August 1, 2014

Review: The Stardust Revolution by Jacob Berkowitz.

On sale now!

Pity the astronomers of yore. Unlike other scientists, they couldn’t take pieces of their objects of study and place them under scrutiny in a lab. Were the heavens truly unchanging and immutable, made of truly different “stuff” than mundane Earthly goods? [Read more...]

Review: Strange New Worlds by Ray Jayawardhana.


It’s weird to stop and think that we now live in a time that we know of the existence 573 new exoplanets, and by the time this cyber-ink goes to press, that rolling number will become obsolete. “In my day,” (my halcyon youth of the 70’s) Eight-tracks where still cool and astronomers guessed that exoplanets had to be common, but no one had as of yet found definitive evidence that this was indeed the case. [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...]

27.04.11: Detecting “Exo-Aurorae.”

Saturian aurora seen in the infrared via the Cassini spacecraft. (Credit: NASA/JPL).

Planetary Scientists may soon have a new technique in their arsenal in the hunt for exo-solar planets. Current tried-and-true methods involve measuring tiny radial velocity shifts, catching a gravitational lensing event, or watching and measuring a tiny dip in brightness as a planet transits its host star. [Read more...]

13.03.11: STRESS: A New Way to Hunt Exoplanets.

Our Milky Way as seen from STEREO. (Credit: NASA/JPL).

A new and innovative tool in the hunt for extra-solar worlds just came to our attention recently. Traditionally, to find these elusive beasts, astronomers utilized ground-based instruments to detect transits, Doppler shifts, and even the occasional odd gravitational lensing event. [Read more...]

04.02.11: A Gravitational Lensing Exoplanet.

Artist’s rendition of the gravitational lens technique MOA uses to spot exoplanets…(All Images coutesy of the MOA Consortium: Used with Permision).

Amid the sexier transiting exoplanet discoveries released earlier this week by the NASA Kepler team came an exoplanet discovered by a lesser known technique; that of gravitational lensing. MOA, or Microlensing Observations for Astrophysics, is a joint Japan/New Zealand venture looking for dark matter objects passing in front of stars and bending their light via gravitational lensing. First predicted by Einstein and famously observed during the total solar eclipse of 1919, several gravitational lenses are now known and documented in nature, from stellar type objects to massive galaxy clusters. [Read more...]

AstroEvent: Catch Jupiter’s Moons in 1-2-3-4 order.

Jupiter+moons at 2200 UT February 1st. (Created by Author in Starry Night).

Recently I’d caught something at a star party that’s worth looking out for; Jupiter’s moons in 1-2-3-4 order. This event happens 3 to 4 times a month, and is always a good teaching moment to name and explain the four Galilean moons. [Read more...]

19.01.11: A Valentine’s Day Flyby.

The view of Comet Tempel-1 as seen from Deep impact in July 2005; this year’s visit plans to be friendlier… (Credit:NASA-JPL-Caltech-UMD).

One down, and one to go… next month, NASA intends to perform another first; the first follow up flyby of a cometary nucleus. The spacecraft is Stardust, and the comet is Tempel 1. Today’s mission briefing gave a glimpse of the action that is in store. Launched in February, 1999 Stardust has performed an array of firsts, including the first sample return from Comet Wild 2 in 2004, and one of the highest re-entry velocities ever attempted during its successful sample return in 2006. [Read more...]

20.06.10: The Low Down on WASP-12b.

An Artist's Impression...NOT a Hubble photograph! (Credit: NASA/ESA/G. Bacon).

An Artist's Impression...NOT a Hubble photograph! (Credit: NASA/ESA/G. Bacon).

 

   A bizarre exo-world just got stranger in the past month, but not in the way many news outlets would have you believe. WASP-12b is destined for a short life, one that we many have been fortunate enough to catch it in the middle of. The story starts in 2008, with the transiting exoplanet’s discovery by the UKs Wide Area Search for Planets (WASP) array. The primary star, WASP-12, is a yellow dwarf located 600 light years distant in the constellation Auriga. Even at that time, it was known that WASP-12b was strange; it whizzed around its star in only 26 hours and had to be sizzling. Now, follow-up measurements with the Hubble Space Telescope and its newly installed Cosmic Origins Spectrograph have indeed revealed a world in peril; at 2800° degrees Fahrenheit, WASP-12b is bloated up to three times the radius of Jupiter, although it only contains 1.4 times its mass. COS was able to identify manganese, tin, and aluminum in the spectra of the atmosphere as the planet transited its host star, using its sensitivity in the ultraviolet to pin down key measurements such as its diameter. This would put the Roche Limit of the planet well beyond what its own gravity can retain. WASP-12b is more than likely feeding material to its stellar host, an act it can’t maintain forever. Calculations show that WASP-12b will cease to exist in about 10 million years or so.  It does, however, give astronomers an opportunity to gather a spectrum for study of a hot Jupiter in action… The WASP-12b story also fueled an avalanche of bad science stories, along the lines of “Cannibal Star 600 Million Light Years Distant Consumes Planet!” as if such a star bent on evil were inbound or headed our way. Never let the facts get in the way of a good story, guys… you keep us science news bloggers employed!

05.06.10: An Exoplanet Family Portrait.

 

The worlds of HR 8799. (Credit: NASA/JPL/CalTech).

The worlds of HR 8799. (Credit: NASA/JPL/CalTech).

 

   Astronomers have recently accomplished another amazing first; the first images of an exoplanetary system taken with modest sized optics. But to perform this feat, several ground-breaking techniques had to first be pioneered. The target was HR 8799, a known exoplanetary system 120 light-years distant in the constellation Pegasus. The instrument was the Hale telescope just north of San Diego, and the team was out of NASA’s Jet Propulsion Laboratory in San Diego. Using a combination of coronagraph and masking the scope down to a diameter of 1.5 meters in diameter, the team was able to capture the above resulting image. The revolutionary “funnel coronagraph” was necessary to block the swamping light of the parent star; the masking was used to maximize the use of adaptive optics. The image was also taken in the infrared, an area of the spectrum in which the young hot planets generate the most energy. “The trick is to suppress the starlight without suppressing the planet light,” Stated JPL Astrophysicist Gene Serabyn. To give you a sense of scale, the three exoplanets pictured lay about 24 to 68 A.U. from their host sun; our own Jupiter orbits at a distance of about 5 A.U. Not only will the technique be capable of being scaled up for the observatory big guns, but it could also prove effective for space-based platforms, where a tension always exists between what astronomers would like to launch and payload limitations. Expect to see more exoplanet images via this method in the near future!

04.06.10- “Hot Jupiters” in Retrograde.

An Artist's family portrait of retrograde exo-worlds. (Credit: ESO/A. C. Cameron).

An Artist's family portrait of retrograde exo-worlds. (Credit: ESO/A. C. Cameron).

 

   A unique battery of telescopes is revealing an unusual feature in many exoplanetary systems. Earlier this year, the Royal Astronomical Society unveiled nine new exoplanets, transiting “hot Jupiters” that cross the face of their parent star as seen from Earth. No big deal nowadays, as the exoplanet count sits at 455 and climbing, and at the time of discovery, 73 transiting exoplanets were known. What makes these beasties so unusual is that they all orbit their host in retrograde orbits. That is, their orbits run counter to their host stars’ rotation.  And just how do you discern the direction of motion for a transiting exoplanet? That’s our impromptu astro-vocabulary builder term of the day; the Rossiter-McLaughlin Effect.  The motion of a spinning star can be discerned in its spectra; the approaching limb is ever so slightly blue shifted, and the receding limb is red shifted. Enter our dark transiting body. When the planet enters the frame, a slight but perceptible “spectral mis-match” occurs; if this occurs in the blue shifted portion, the orbit is prograde; in the red shifted end, the orbit is retrograde. The observations were conducted via the Super-WASP (Wide Angle Search for Planets) consortium. This is a pair of robotic instruments each consisting of eight CCD coupled telephoto lenses (they’re Canon 200mm f/1.8s!) each capable of capturing a field of view 7.8° degrees square. Super-WASP North is located in the Canary Islands, while Super-WASP South is stationed at the site of the South African Observatory. These enable a cost affordable way to survey the entire sky looking for the tiny signature dimming of a transiting exoplanet. Conceived in the 1990s by Don Pollacco, Super-WASP has identified 26 extra-solar planets to date. How these retrograde hot Jupiters came to be remains to be solved… but it is still truly awesome how much data we can glean from a tiny string of photons!

12.05.10- White Dwarf Lite?

 

A comparison of Kepler's latest planetary finds. (Graphic Credit: NASA).

A comparison of Kepler's latest planetary finds. (Graphic Credit: NASA).

 

   The Kepler space telescope may have bagged an unexpected prize during its hunt for exo-planets. Along with five published exoplanets illustrated above, Kepler snared two potentially bizarre objects. Dubbed KOI (Kepler Objects of Interest) -81 and 74, these companions actually appear dimmer passing behind the parent star rather than in front of it. This suggests a bright luminous object(s) with an Earth-like diameter but much more massive… a white dwarf? Possibly, but the objects seem to be physically too large to fit this class of objects. White dwarfs have an upper limit of about 1.4 solar masses, also known famously as the Chandrasekhar limit. Recently, scientist Jason Rowe of NASA Ames research center has been able to directly measure the masses of these companions by measuring the way the companions physically warp, or distort the bodies of their primary companions. The result; these stars are in the realm of 0.1 solar masses, which would make them some the lightest white dwarfs known. Obviously, this also becomes a problem because although small and luminous, KOI-81 and -74 probably aren’t supported solely by electron degeneracy pressure that characterizes standard classical white dwarfs. The situation just got stranger and stranger… were these objects large super-heated planets or light white dwarfs?

Enter an international team of astronomers meeting at Kavli Institute in Peking (Beijing) China. Using an innovative technique known as Doppler boosting, they were able to pinpoint the mystery objects mass at 0.2 solar masses, on the low end but still in the realm of a white dwarf. This makes even more sense if one considers a white dwarf accreting mass from a primary companion, ala a Type 1A supernovae candidate…(hey, didn’t we write in this space last week about the lack of these beasties?)   Doppler boosting works in terms of catching subtle fluctuations in the brightening of an approaching object as measured by photons received over a given unit of time and dimming as it recedes…altogether a complicated affair, considering this must be untangled from a flurry of other signals. This unexpected find illustrates that surreptitious discoveries are often the norm in astronomy, if only someone is willing to look for them!

Review: How to Build a Habitable Planet by James Kasting.

Some years ago, a book entitled Rare Earth was published amid much controversy. The central thesis of this work was that events that led to the eventual habitability and diversity of life and intelligence on Earth were so improbable, as be near to impossible to replicate elsewhere in our galaxy. The book marked a sort of change in thinking in the realm of exobiology, one from “intelligent civilizations are everywhere” championed by the late Carl Sagan to the concept that we may be the only ones, if not the first.

Out now from Princeton Press!
Out now from Princeton Press!


[Read more...]

24.04.10-Our Existence: Justified.

(Credit: NASA/JPL).

(Credit: NASA/JPL).

 Earth: Safe & Sound?

   The formation of the Earth poses a key dilemma to planetary accretionary theory; namely, why are we here at all? Standard models would say that the Earth and other planets coalesced out of the proto-solar nebula to form. However, spiral density waves within the same nebula should have drawn down orbital energy to shorten the planets orbit, slowly drawing it in. Looking at other “hot Jupiter” systems, that’s just what we see; large gas giant worlds that formed further out, only to migrate inward into tight orbits… just how did we end up in our nice, neat orbit?

Now, computational astrophysicist Mordecai-Mark Mac Loc at the American Museum of Natural History may have the answer. Accounting for temperature and spin variability, resonance key holes can occur; planets like Earth may simply spiral inward and get hung up in these safe zones between dragging pressure waves. Of course, a majority of proto-planets don’t make the cut and simply spiral inward to a fiery end, but they’re not around for us to see today. One discovery that would perhaps give observational weight to this theory would be the discovery of exo-Earths also parked in nice neat orbits… the Kepler space telescope may pave the way for this discovery as it stares off into Cygnus. For now, thank computational mathematics that you’re here reading this, just as it says you should be!

18.04.10- Zeroing in on Nearby Exoplanets.

 

(Credit: NASA/JPL).

(Credit: NASA/JPL).

A scale comparison of a possible Super-Earth.

It’s hard to believe that a little less than two decades ago, no extra-solar planets were known. Now, the count climbs daily, and platforms like the Kepler Space Telescope threaten to launch the tally into the thousands. Recently, an international team of astronomers made six new discoveries in two nearby star systems that may eventually lead towards the cosmic Holy Grail; an exoplanet resembling Earth. The team was led by prolific planet hunter Paul Butler and Steve Vogt, who discovered the super-Earths by combining radial velocity data gathered from the Anglo-Australian telescope and the Keck observatory. First up is 61 Virginis, a Sun-like star 28 light years away. This system has always been of interest to astronomers because it is a near twin to our own Sun and is on the short list for NASA’s Terrestrial Planet Finder. The team discovered three worlds ranging in mass from 5 Earths to 25. In addition, follow-up studies with the Spitzer Space telescope find evidence for a dust ring around 61 Virginis about twice Pluto’s distance from our own Sun. The second discovery is one 7.5 Earth mass planet and a possible two more found around the star HD 1461 in the constellation Cetus about 76 light years distant. Again, HD 1461 could pass for our Sun in terms of age, size, and mass. Both stars would be visible to the naked eye under reasonably dark skies. It remains to be seen if these worlds are rocky terrestrial planets or Uranus-like slush balls. Evidence is mounting, however, that planets may be common around nearby Sun-like stars. The innermost planetary detection for 61 Virginis also represents the smallest amplitude discovery ever made by astronomers. These discoveries were backed up by brightness measurements made by robotic telescopes based in Arizona and operated by Tennessee University’s George Henry. This ruled out the possibility that the amplitude variations seen were due to variability or “starspots”. The Lick-Carnegie Exoplanet Survey Team will also soon have a new weapon in its arsenal; the recently completed Automated Planet Finder (APF) Telescope atop Mount Hamilton. All that’s needed now is for the Discovery Channel to fund a new hit series; The Exoplanet Hunters!

Astro-Challenge: What’s so Special About 51 Pegasi?

A northern hemisphere finder chart for 51 Peg, looking NW after dusk. (Created in Starry Night).

A northern hemisphere finder chart for 51 Peg, looking NW after dusk. (Created in Starry Night).

It’s hard to imagine a time before we knew of worlds beyond our own solar system. These days, extra-solar (or “exoplanets”) are back page news, as discoveries occur almost daily.  But scant decades ago (Waaay back in the pre-Internet Stone Age of the early 1990’s) no exoplanets were known, and the entire field was open to great conjecture. This was also one of the great variables underpinning the famous Drake Equation which attempts to quantify how many intelligent civilizations might exist in our galaxy; i.e. “how many stars possess solar systems?” That all changed in the 90’s, and the discovery of a planet in October 1995 by Geoffrey Marcy and Paul Butler orbiting the star 51 Pegasi in the constellation Pegasus was pivotal in opening the flood gates. [Read more...]

Review: Confessions of an Alien Hunter by Seth Shostak.

 

 

Out now from National Geographic Press!

Out now from National Geographic Press!

Seth Shostak has a unique tale of scientific inquiry to tell. At its heart are questions that some of the greatest thinkers of our time such as Jill Tarter and Carl Sagan have pondered; are we alone? Why are we here? How common or unique are we as a species?

Only very recently has the topic and field of exobiology become a respectable science, and Confessions of an Alien Hunter by Mr. Shostak and out by Nation Geographic Press reflects on how far we’ve come in this very elusive field and where we might be headed. [Read more...]

26.10.09:Seeing Starspots.

A simulation of Corot-2a with transiting hot Jupiter and starspots. (Simulation and phot by author).

A simulation of Corot-2a with transiting hot Jupiter and starspots. (Simulation and photo by author).

We know more about our Sun than any other star because it gives us the opportunity to study solar activity up close. But just how normal is it? Recently, astronomers have been able to spy activity on other suns, teasing the data out of exoplanet transits. These are planets that happen to cross the tiny visible face of their parent star as seen from our line of sight and thus exhibit a tiny but measurable dip in their apparent brightness. Earlier this year, a team at the Hamburg Observatory has been refining this technique by monitoring the star Corot-2a. A younger Sun-like star, Corot-2a spins once every 4.5 earth days and possesses a transiting “hot Jupiter” which orbits once every 1.74 days. Examining a statistical analysis of the light curve as seen by the European Space Agencies’ (ESA) prolific Corot space observatory has yielded “notches” in the smooth curve, a tell-tale sign of “starspot” activity. This was conducted over 80 successive transits. The goal is to begin puzzling together a “butterfly diagram” for alien suns, much like the familiar 11 year cycle diagram yielded by Sporer’s Law for our own Sun. Doubtless, other suns follow different cycles, and this data will add to our understanding of stellar evolution. This will also answer such questions about our own Sun, such as; why do sunspots never form above a particular latitude? Are there larger interwoven cycles? And just what was our Sun like in its juvenile days?