CoRoT-2a: The First Exoplanet to Orbit Around Two Suns

Imagine a world with double-sunsets, double-sunrises, and maybe simultaneous dual-solar transits? Although understanding concerning the dual-solar transits is a little too advanced for now (!), CoRoT has located a world that astronomers have only dreamed of. This world, now designated CoRoT-2a, is a planet that orbits a binary star system, which is, stars which orbit each-other. In addition to this matter, it's pretty amazing to find an exoplanet orbiting two stars, which are orbiting each-other (around a hypothetical orbital point). Binary eclipses take place quite often, but yet, this action isn't at all alien.

Similar to CoRoT-2a, astronomers have located and studied intensely the star-exoplanet system of Kepler-16 (there are many animations and a continuation of facts). This is a unique system comprised of the main star (Kepler 16A) with the exoplanet (Kepler 16b) and another star (Kepler 16B) both orbiting around it, while the first star is also orbiting around that imaginary center of the system. In a paper entitled Kepler-16: A Transiting Circumbinary Planet, the authors write in the abstract: "Data from the Kepler spacecraft reveal transits of the planet across both stars, in addition to the mutual eclipses of the stars, giving precise constraints  on the absolute dimensions of all three bodies." Now, this system is quite comparably different to new CoRoT-2a, but both have many things in common.

 

"This discovery confirms a new class of planetary systems that could harbor life," Kepler principal investigator William Borucki said. "Given that most stars in our galaxy are part of a binary system, this means the opportunities for life are much broader than if planets form only around single stars. This milestone discovery confirms a theory that scientists have had for decades but could not prove until now."

As mentioned before, but not defined; these systems are 'circumbinary.' Astronomically translated, a circumbinary system is one that usually incorporates a binary star pair orbiting around each other with another object, usually a star but in this case an exoplanet, orbiting around those. The model above correctly interprets the definition. Astronomers know of these eclipses that are made by a simple point: they are at our vantage. Every system that we know of (usually) transit stars as viewed from earth. After you think about this fact for a while, you can just imagine the possibilities. If Kepler has located 1235 transiting objects (yet not confirmed) and has 2165 binaries that might be; do not forget that these are just the objects visible in the direction of earth. Therefore, there could be thousands, maybe millions, of other exoplanets transiting not at the vantage point to earth.

NASA describes an eclipse: "When the smaller star partially blocks the larger star, a primary eclipse occurs, and a secondary eclipse occurs when the smaller star is occulted, or completely blocked, by the larger star." During the time of research and discovery of the objects, after the first two objects had been found (on account of their dipping), astronomers noted that even later on, the brightness of this irregular system dipped...which lead to the discovery of a third body. "The additional dimming in brightness events, called the tertiary and quaternary eclipses, reappeared at irregular intervals of time, indicating the stars were in different positions in their orbit each time the third body passed. This showed the third body was circling, not just one, but both stars, in a wide circumbinary orbit." 

Chandra's CoRoT-2a

Read more HERE

Video (courtesy of NASA) about CoRoT-2a (I a very sorry - I tried to embed the video...blogger didn’t like it...)

90 Antiope's Dual Asteroid Occultation - The Results

After occulting each other (and the star LQ Aquarii), 90 Antiope made a memorable day this past July 19. That dual-asteroid occultation was a treat for those on the Pacific coast, becasue these events are the events you don't see everyday. After waiting almost two months, we have finally got the report in from Sky & Telescope concerning what actually happened that commemorated day. Although asteroid occultations are not very impressive as grand-scale total solar and lunar eclipses, asteroid occultations "can be just as rewarding — and sometimes have far more scientific value," Kelly Beatty writes in his post, Antiope Occultation Yields Double Bonanza.

4 Days before occultation. Photo Credit giant Keck Telescope: W. Merline & others

Considering carefully the last remark, 'far more scientific value' (from the quote above), astronomers have realized the complexity and scientific values of this occultation. To describe this event in detail, from our earlier post entitled Rare Event: Dual Asteroid Occultation:

July 19, Tuesday, brings us a rare event of an occultation of dual (binary) asteroid 90 Antiope. Between the hours of 10:18 to 10:25 Universal Time, 90 Antiope will occult one its members, so us here in America can see it. If you're on the east coast - you're out of luck, as sad as it is. Only the northeast to southwest portions across central Saskatchewan, southeastern Alberta, western Idaho and Montana, northern Nevada, and north-central California will be able to witness this rare event.

Sky & Telescope points out three advances in why this occultation was so beneficial, despite the low magnitude of the binary pair and bright condition of the moon.*

1) Despite the fact that 90 Antiope is just at magnitude 8.27 together (9.02 each separate), the star occulted was rather bright (magnitude 6.7) and could be viewed easily by small, personal telescopes.
2) Visible, 90 Antiope is comprised of two bodies, each approximately 90 kilometers across, which when viewed in a stellar occultation, is very impressive. (90 kilometers = 55 miles).
3)The predicted track of occultation visibility crossed a well-populated region of the United States and portions of Canada.

"I'm happy to report that Antiope did not disappoint," Beatty writes. Fifty plus observers plotted their estimations concerning the occultation, as the plot below demonstrates. If you can note, the southern object has a rather well pronounced missing side, perhaps a crater, but astronomers are not entirely sure. Since 90 Antiope was discovered in 1888 by German astronomer Robert Luther, many observers have watched these objects in their celestial course; a myriad have noted that irregularity in perfect proportion.

Each multicolored line shows an approximate estimate on the path of occultation. Credit: IOTA, David Dunham

Concerning the actual occultation of LQ Aquarii, astronomer William Merline (leader of a team from the Southwest Research Institute; giant Keck Telescope in Hawaii) had predicted that each component of 90 Antiope would "clip" the edges of the star. Because of this, a 'partial' occultation is granted, but no-one expected that the gap would be that wide. "A few observers in the middle had no occultation by either component," explains David Dunham, IOTA's president. "We're debating whether to call these central miss observations 'Moses chords' or 'Hercules chords', for threading the Pillars of Hercules to gain new knowledge."


In a grandiose conclusion, this occultation has provide a significant amount of scientific information. Sky&Telescope ranks it to be "among the most remarkable and scientifically valuable in recent years." Although pure irony, in the era of the 1970s, when astronomical understanding was nothing compared to today**, astronomers argued that there was no such thing of dual asteroids (See our other article, under title 'The History...Binary-Asteroids'). David Dunham was one that actually supported this 'outlandish' idea, and he finally did succeed in his efforts. This was resolved due to the fact of Galileo and Ida & Dactyl (lower portion of article). Today more than 200 multiple asteroids are known. (I recommend that link immensely for study).

Ida and Dactyl, thanks to Galileo spacecraft.

Sky&Telescope: "You can click here to learn more about IOTA and here for predictions of upcoming occultations that you might be able to observe. And you'll find several articles right here on SkyandTelescope.com about how to view and record occultations."

___
*Sky&Telescope takes credit for the formation of the ideas, I take credit for the embellishment of them - and they are embellished.  
**This is a eloquent simile, yes, there was astronomical understanding in the 1970s, but becasue of today's astronomy knowledge and equipment, we know much more. 

Events for the Week 7/26 to 7/29

Events for Tuesday, July 26, 2011

Mars shines bright around 4 am local time juts before the Sun starts to rise. It's near Aldebaran in constellation Taurus, glowing about a half-magnitude brighter than the red world itself. Watch out for the occultation tomorrow! "Mars lies directly between the two stars that mark the Bull’s horns: Zeta (ζ) and Beta (β) Tauri. A waning crescent Moon adds to the scene from its perch nearly due north of Aldebaran," Astronomy.com writes us. There is also another planet in view at the time. Mercury will be shining in bright twilight with Regulus three degrees above in the western horizon! What a beautiful site!

 

 

Events for Wednesday, July 27, 2011

This morning the occultation of Mars takes place. Posted in the previous article:

After Venus occulted over the Mediterranean last month, it's time for Mars to take the stage. Although 2011 is somewhat of a bad year for occultation viewing, Mars will still be occulted. But don't get your hope up! People here in America won't be able to see it. On July 27, 2011 at 16:50:54 UT over the Pacific and parts of South America. Specifically, this occultation will be viewed from the French Polynesia, Chile, Peru, and Argentina, but won't be anything impressive."The good thing about this occultation is that the Moon is only 16% illuminated. This means minimal lunar interference," AstronomyLive.com encourages. READ MORE

At night: Vega returns to zenith tonight, so viewing the bright star is perfect.

Events for Thursday, July 28, 2011

Asteroid Vesta is coming to opposition which is a key time to observe. August sixth is the date, and here is an excerpt from our new Minor Planets Viewing Page where you can read and see more about all the minor planets in our solar system.

To view these asteroids, Vesta will be up all night (especially around 3 am local time); but both objects will be in best view at opposition. Opposition is appropriately when an object is the highest in the night sky, as viewed from your position on earth. Vesta is in opposition August 6, and Ceres, September the 16th. Here is a good magnitude list to show you the magnitude of the object on a certain date. The object will be the brightest on opposition, as the chart reflects. READ MORE

Comet Garrard also returns to the night sky; in Pegasus.

Events for Friday, July 29, 2011

Tonight, a few special stars are in the spotlight. Famous binary Agol in constellation Perseus reaches minimum brightness tonight at 3:32 am EDT, when it comes to 3.4 magnitude. This is in eclipse. You can start to view this around 10:30 pm on the 28 in North America, and see the eclipse. Although it does orbit around each-other every 2.78 days, it's rare that eclipses occur...think: the moon orbits around the Sun every month, but do eclipse occur every month? No! The eclipse must be on the ecliptic...so Agol must be on the ecliptic as well. 

 

Example of Agol...a binary

Altair, another bright star of interest shines bright tonight as well. It's a very close star, at about 17 light-years away, and spins so fast that it's elliptical shaped!

Sorry I fail to provide you the Planets' Positions, but come to this page, which has it all for you.

Solar System Calendar:

26 Jul 2011 07:10:41 Aphelion of Mercury, 0.46670 AU from Sun
27 Jul 2011 03:01:38 Max. South Declination of the Moon, 23.3°
27 Jul 2011 12:03:07 Descending Knot Passage of the Moon
27 Jul 2011 16:49:49 Occultation of Mars by the Moon, 0.5°
29 Jul 2011 13:49:11 Opposition of Pallas, 9.3m

Have a great viewing this week!