November 19, 2017

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!

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!

26.10.09:Seeing Starspots.

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?



19.10.09: 32 New Exoplanets Revealed!

Anybody notice the exoplanet tally on our front page hop up to 402 this morning? That’s because the European Southern Observatory (ESO) revealed a stunning 32 (count em!) new exoplanets identified this morning at their conference at Porto, Portugal. The discoveries were thanks to HARPS, the High Accuracy Radial Velocity Planet Searcher, a sensitive spectrograph attached to the 3.6 meter telescope at La Silla. First installed in 2003, HARPS has thus far discovered 75 of the 400+ worlds now known, or nearly 25%! today’s haul represents the largest single day release. Any special firsts? Well, the grab bag of exo-worlds substantially increases the pool of “super-earths”, as well as three planets found orbiting metal deficient stars, something that may be cause for tweaking planetary formation theory a bit. HARPS is capable of measuring radial shifts as small as 2 miles per hour, an impressive feat. The gauntlet has now been thrown; will the Kepler space telescope rise to the challenge as it stares into Cygnus looking for exo-transits? Do we sense a “exoplanet-war” brewing on mountain tops and chat boards across the world? Stay tuned!

The Moon joins a Planetary Three-Way.

Early risers this week will awaken to a fine sight; a three way dance between Mercury, Saturn, and Venus, joined by the waning crescent Moon on the 16th. Look towards the east, about a half hour before local sunrise. Mercury has just passed greatest elongation on the 6th of this month, and thus will be swiftly sinking back to the horizon morning by morning. Venus will continue to shine high in the east at dawn, and Saturn, fresh from conjunction with the Sun last month, will be the faintest and slowly slide upwards past the pair of inferior planets this week.

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02.10.09: A Small Observatory Helps with a Big Discovery.

When it comes to cutting edge astronomy, many think of lofty mountaintop behemoths, such as Keck, or the orbiting Hubble Space Telescope. But how many of us think of… Gainesville, Florida? This article caught my eye this morning because its literally right in our backyard here at Astroguyz HQ in Hudson, Florida. As any would-be Floridian astronomer knows, the Sunshine State is not an optimal environment for astronomy, as humid, damp, East Coast conditions predominate. But that didn’t stop astronomers at the University of Florida in Gainesville from using the Rosemary Hill Observatory in nearby Bronson to help with observations of a transiting exoplanet; HD 80606b. 200 light-years distant, this hot-Jupiter is in an extremely eccentric orbit and was only recently realized to be a transiter, i.e. to occasionally pass in front of its host star as seen from Earth. Astronomers, however, were faced with a problem; the next transit was due occur June 4th of this year, when HD 80606b would be low in the twilight sky. This meant that observations of the eclipse could only occur over a short span from any given longitude. Enter U of F astronomers Ford, Reyes and Colon, who realized that Rosemary Hill might just be positioned to catch such an event. Located, as is most of Florida, at a scant 140 feet above sea level, Rosemary Hill may just qualify as the “lowest” observatory in the world. It sports 30” and 18” reflecting telescope(s), which are primarily used for education and training, as the U of F astronomers tend to travel to the “big guns” in the Canary Islands for “serious” research. The night of the 4th, however, Rosemary Hill showed its stuff; as a participating observatory in Massachusetts was clouded out, leaving the Gainesville astronomers as key to gathering data at their respective longitude. Colon noted that the experience of actually guiding the telescope and monitoring the star during transit was “definitely unique” and different from the remote observing now prevalent at larger observatories… the data gathered will go far towards understanding this bizarre exoplanet and its 111 day orbit. And the moral of the story is…every telescope can contribute, even your home town observatory!

23.9.9 CoRoT-7b: A Rare Earth.

The “Super-Earths” are getting smaller. Recently, the ESA announced that an exoplanet discovered on February 3rd of this year by the CoRoT (Convection Rotation and planetary Transit) satellite is one of the lightest yet… at about five Earth masses, this transiting exoplanet is about twice the diameter of the Earth. But don’t pack your bags just yet; CoRoT-7b as its designated, also zips around its host star every 20.4 hours at a distance 23 times closer than Mercury! This bakes the rocky world with temps in excess of 2000 degrees Celsius. The parent star itself is slighter cooler and younger than our Sun. Follow up measurements by HARPS, the ground based High Accuracy Radial velocity planet Searcher spectrograph at the La Silla Observatory in Chile helped tease out the radial speed and yielded an unexpected bonus; another Earth-like world, CoRoT-7c, which orbits at a relatively sedate 3 days and 17 hours and is 8 times the mass of the Earth. Such bizzare systems may become the norm in the coming years, as exoplanet detection technology becomes more sensitive. The CoRoT-7 system is located about 500 light years away in the plane of the Milky Way galaxy in the constellation Monoceros.



21.9.9 Will Kepler spot “exo-moons?”

Let the staring begin… the Kepler spacecraft has its shutters open and is now ready for business. Just out the gate, the results have been astounding. First, there was the discovery of HAT-P-7b, a transiting exo-planet that was spotted last month, complete with atmosphere. Now, calculations have shown that Kepler may be sensitive enough during the span of its four year mission to detect another first; exo-moons, or Earth-mass moons orbiting Saturn-mass planets. Kepler is in an Earth trailing orbit and sports a 0.95 meter 95 mega pixel (that’s an array of 42 2200×1024 pixel each CCDs!) aperture camera that will stare at the star-rich Cygnus-Lyra region looking for tiny dips in the apparent brightness of over a 100,000 stars. Expect the tally of new exo-planets to climb in the coming months!


3.8.9: Jupiter Occults a Bright Star.

Lots has been afoot in the Jovian system as of late. As you train that 10” Dobsonian on the ever evolving black spot gracing Jupiter’s cloud tops, I turn your attention to another unique event about to occur tonight; the occultation of a bright star by the large gas giant. The star is 45 Capricorni, which is currently crossing our line of sight with Jupiter. At about sixth magnitude, it will masquerade as a Galilean satellite over the coming days.The actual occultation begins at 23:00 Universal Time (UT) on August 3rd and lasts until 1:00 UT on the 4th. Europe, Africa, the Canadian Maritimes and extreme northern New England will be well placed to see this rare occultation; the remainder of the Americas will see 45 Cap rise with Jupiter at about 9 P.M. local. An occultation of a bright star by a planet is rare because planets are intrinsically small targets in terms of visual diameter, and stars that they can occult are constrained to those along the path of the ecliptic. Speaking of which, the four large moons of Jupiter are also currently under going a fascinating series of mutual eclipses as we transit their respective orbital planes; check out the link above for more info, and watch the occultation of 45 Cap if you get a chance. Some things to watch out for; does the star “wink in, wink out” in a step wise fashion, or fade gradually in and out? You could be seeing evidence of Jupiter’s atmosphere refracting the starlight; or perhaps this is glimpse 45 Cap’s binary companion! Also known as HIP 107302, this star is also listed as a close spectroscopic double. This will also be the brightest star that Jupiter has occulted since 1952.

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27.07.9: What Ails Jupiter?

Something has slapped the largest planet in our solar system as of late. A large black spot has emerged in Jupiter’s southern polar region, reminiscent of the Shoemaker-Levy 9 collision of 15 years ago. Initially discovered by Anthony Wesley of Australia utilizing a 14.5” reflector early last week, the discovery was backed up mid-week by NASA’s Infrared Telescope Facility in Mauna Kea, Hawaii. Looking similar to a Galilean satellite shadow, it has all the hallmarks of an impact. Will it evolve and develop over the coming weeks and months? By the time this goes to (word)press, we hope to get a glimpse of it here at Florida Astroguyz HQ. [Read more...]

Astro-Event of the Week:03.23.09:Can you spot Venus at Inferior Conjunction?

Warning: Do not attempt this weeks’ astro-feat unless the Sun is properly blocked, preferably just below the horizon! Sweeping the area near the Sun with optical equipment introduces the very real possibility of momentarily pointing at the Sun, which can cause optical damage!

This week’s observing challenge is a unique attempt, and will put you in league with a handful of skilled observers that even realize this is possible. It is not generally appreciated that Venus’s orbit is tilted 3.4 degrees in relation to our own, as represented by the ecliptic.

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Astro-Event of the Week; March 9th-15th; A Transit of Titan.



This week’s astro event is a special one. Anyone who has been tracking the planet Saturn as of late knows that the ring plane is nearly edge on. One consequence of this is a series of rare transits are underway, and one of the best occurs this week. Saturn’s largest moon, Titan will transit Saturn’s disk for viewers in North American longitudes westward in the early AM hours of Thursday, March 12th, 2009.

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Astro-Event of the Week; February 23rd-March 1st; A Close Conjunction.

Lots of happenings in this last week of February… the pick for the astro-event of the week was a toughie. I choose the Friday close conjunction/occultation of Venus and the Moon, as it’s one of the closest of the year! And it’s easily observed with the naked eye, and highly photogenic to boot!

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Astro-Event of the Week: September 2nd-8th 2008; A Double Shadow Transit!

The Jovian system of moons is a place where things happen. Shadow transits are probably the most dramatic event to be seen in this “mini solar system.” It’s definitely cool to watch the inky black dot shadow of a moon sliding silently above the cloud tops of Jupiter.

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Astro Event of the Week 9-16th, 2008.

Welcome to a new weekly feature here at Astroguyz… each Monday, our goal will be to present some new and interesting celestial event that you can see from your own backyard. If the event is happening anytime from Monday evening, US East Coast time, up through early next Monday, you’ll read about it here. We’ll also tie in a vocabulary “astro-word of the week.” So, as Fat Albert says, “If you’re not careful, you just might learn something before it’s done!”

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