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Hint of 150 MHz radio emission from the Neptune-mass extrasolar transiting planet HAT-P-11b
Next Big Future ^ | 2/24/2013 | Brian Wang

Posted on 02/25/2013 10:34:07 AM PST by Red Badger

ince the radio-frequency emission from planets is expected to be strongly influenced by their interaction with the magnetic field and corona of the host star, the physics of this process can be effectively constrained by making sensitive measurements of the planetary radio emission.

Up to now, however, numerous searches for radio emission from extrasolar planets at radio wavelengths have only yielded negative results. Here we report deep radio observations of the nearby Neptune-mass extrasolar transiting planet HAT-P-11b at 150 MHz, using the Giant Meterwave Radio Telescope (GMRT).

On July 16, 2009, we detected a 3σ emission whose light curve is consistent with an eclipse when the planet passed behind the star. This emission is at a position 14′′ from the transiting exoplanet’s coordinates; thus, with a synthetized beam of FWHM∼16′′, the position uncertainty of this weak radio signal encompasses the location of HAT-P-11. We estimate a 5% false positive probability that the observed radio light curve mimics the planet’s eclipse light curve. If the faint signature is indeed a radio eclipse event associated with the planet, then its flux would be 3.87 mJy±1.29 mJy at 150 MHz. However, our equally sensitive repeat observations of the system on November 17, 2010 did not detect a significant signal in the radio light curve near the same position. This lack of confirmation leaves us with the possibility of either a variable planetary emission, or a chance occurrence of a false positive.

Although we are not able to draw a definitive conclusion on 150 MHz radio emission from HAT-P-11 b, at the very least the hint of radio detection presented here identifies HAT-P-11 b as a prime candidate for many follow-up observations in the near future. The priority is to try to confirm the present tentative detection, via re-observation with GMRT at 150 MHz and/or new observations with LOFAR in the 30-250 MHz range (providing a 1-100 mJy sensitivity depending on the observation parameters used; van Haarlem et al., submitted, 2013) and UTR-2 in the 10-30 MHz range (providing a sensitivity of ∼100 mJy; Ryabov et al. 2004). The observed spectral range can also be extended toward shorter wavelengths using GMRT, with even higher sensitivities of ∼1 mJy at 240 MHz and ∼50 µJy at 614 MHz (e.g., Lecavelier des Etangs et al. 2009). Observations over a broad range of frequencies will, with any luck, allow confirmation of the existence of the emission and better constraints on the planetary magnetic field strength and determination of the radio spectral index.

The future observations should also be distributed at multiple epochs and at different orbital phases of the planet to characterize the suspected variability of the radio emission in terms of duty cycle, as well as the radio emission as a function of the star-planet angle and the emission directivity (CMI produces narrowly beamed radio emission). In this context, Hess and Zarka (2011) have analyzed all the observables that could be derived from a broadband dynamic spectrum with a sufficient signal-tonoise ratio.

In the long term, it should be possible to investigate if the radio emission from extrasolar planetary systems correlates with the stellar spot activity. In this context, HAT-P-11 represents the target of choice because the Kepler mission has recently demonstrated the possibility of following the spot activity and perhap even of drawing the butterfly diagram of surface spots for this star.

Radio observations of different types of exoplanets are also crucial for comparative exoplanetology. For instance, observations of the other transiting hot-Neptune GJ436 b (Gillon et al. 2007) will allow comparison with a planet similar in mass but orbiting an M-dwarf star which is half the mass and radius of HAT-P-11 and known to have a strong Far-UV and Lyman-αoutput (Ehrenreich et al. 2010). With a 6.55 Earth mass, the nearby exoplanet GJ1214 b should also provide an opportunity to undertake search for radio emission from a water-rich lower mass super-Earth planet (Charbonneau et al. 2009; D´esert et al. 2011). In the near future, more sensitive observations at even lower frequencies will become feasible with the LOFAR observatory, providing a great boost to exoplanetary research.


TOPICS: Culture/Society
KEYWORDS: amateurradio; astronomy; exoplanet; ham; hatp11b; radio; space; xplanets
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To: Rebel_Ace; Red Badger

What I’m going to have to look up is the definition of a radio light curve. The term doesn’t make sense to me.


41 posted on 02/25/2013 11:50:17 AM PST by FreedomOfExpression
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To: Red Badger
I am from planet HAT-P-11b and you are spreading very false rumors. I take umbrage and will do something about it!

All your rumors are belong to us!

FMCDH(BITS)

42 posted on 02/25/2013 11:51:48 AM PST by nothingnew (I fear for my Republic due to marxist influence in our government. Open eyes/see)
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To: FreedomOfExpression

http://en.wikipedia.org/wiki/Light_curve


43 posted on 02/25/2013 12:15:17 PM PST by Red Badger (Lincoln freed the slaves. Obama just got them ALL back......................)
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To: FreedomOfExpression

Perhaps the writer meant to say, “radio/light curve”.........


44 posted on 02/25/2013 12:17:26 PM PST by Red Badger (Lincoln freed the slaves. Obama just got them ALL back......................)
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To: nothingnew
Alien: You wanna piece of me, punk?........
45 posted on 02/25/2013 12:20:31 PM PST by Red Badger (Lincoln freed the slaves. Obama just got them ALL back......................)
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To: Red Badger

Nope. The Honeymooners. What happens when we get the Gork IV equivalent of “Pow, to the moon?”


46 posted on 02/25/2013 12:21:39 PM PST by ModelBreaker
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To: nothingnew
Alien: You wanna piece of me, punk?.........
47 posted on 02/25/2013 12:25:50 PM PST by Red Badger (Lincoln freed the slaves. Obama just got them ALL back......................)
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To: ModelBreaker

Too far away for that. They might have overheard the War of the Worlds broadcast of 1938, though........


48 posted on 02/25/2013 12:27:46 PM PST by Red Badger (Lincoln freed the slaves. Obama just got them ALL back......................)
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To: Red Badger

Bump to read later.


49 posted on 02/25/2013 12:28:11 PM PST by techcor
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To: JRandomFreeper
http://en.wikipedia.org/wiki/6-meter_band As transceivers have become more available for the 6-meter band, it has quickly gained popularity. In many countries, including the United States, access is granted to entry-level license holders. Those without access to international HF frequencies often gain their first taste of true long-distance communications on the 6-meter band. Many of these operators develop a real affection for the challenge of the band, and often continue to devote much time to it, even when they gain access to the HF frequencies after upgrading their licenses.
50 posted on 02/25/2013 12:32:50 PM PST by Red Badger (Lincoln freed the slaves. Obama just got them ALL back......................)
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To: bkepley

I use subspace to send status reports to the home planet. Different strokes for different folks, I guess.


51 posted on 02/25/2013 12:47:01 PM PST by cuban leaf (Were doomed! Details at eleven.)
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To: Red Badger
Its just an alien Ham with an off frequency 2m TX....probably asking someone to....

Pack my bags with twelve dozen Phoenician liquor jugs

and some best bent wire.

52 posted on 02/25/2013 12:50:57 PM PST by spokeshave (The only people better off today than 4 years ago are the Prisoners at Guantanamo.)
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To: Red Badger
Thanks!
Still not too clear, though.
53 posted on 02/25/2013 12:50:57 PM PST by FreedomOfExpression
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To: Red Badger
Yep. I've kept my advanced ticket because they are rare these days, and even with my HF rigs, I still enjoy openings on 6 meters when you can work from Texas to California on a 5W handi-talki.

/johnny

54 posted on 02/25/2013 12:52:49 PM PST by JRandomFreeper (Gone Galt)
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To: FreedomOfExpression

Basically, it’s measuring the intensity of the signal, and charting its undulations. If it has a periodic rise and fall, it would indicate that the object is rotating at the rate of the peaks............


55 posted on 02/25/2013 1:16:12 PM PST by Red Badger (Lincoln freed the slaves. Obama just got them ALL back......................)
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To: Aevery_Freeman

Bingo!


56 posted on 02/25/2013 3:15:08 PM PST by BenLurkin (This is not a statement of fact. It is either opinion or satire; or both)
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To: Red Badger
Alien: You wanna piece of me, punk?.........

No, I want all of you...alien.

FMCDH(BITS)

57 posted on 02/25/2013 7:15:34 PM PST by nothingnew (I fear for my Republic due to marxist influence in our government. Open eyes/see)
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To: Red Badger; KevinDavis; annie laurie; Knitting A Conundrum; Viking2002; Ernest_at_the_Beach; ...

Thanks Red Badger!
 
X-Planets
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Google news searches: exoplanet · exosolar · extrasolar ·

58 posted on 02/25/2013 8:39:43 PM PST by SunkenCiv (Romney would have been worse, if you're a dumb ass.)
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