Author Topic: Pale Red Dot  (Read 70019 times)

Offline matthewkantar

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Re: Pale Red Dot
« Reply #360 on: 12/14/2017 11:18 PM »
Three transits could be a long wait if the planet is as far out as our ice and gas giants.

Matthew

Offline Star One

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Re: Pale Red Dot
« Reply #361 on: 02/26/2018 07:41 PM »
Powerful Flare from Star Proxima Centauri Detected with ALMA

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ALMA data reveal that a powerful stellar flare erupted from Proxima Centauri last March. This space weather may make that system rather inhospitable to life after all.

https://public.nrao.edu/news/2018-alma-flare-proxima/

Offline Star One

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Re: Pale Red Dot
« Reply #362 on: 02/27/2018 08:02 PM »
Article discussing the possible implications of the above paper.

Proxima Flare May Force Rethinking of Dust Belts

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News of a major stellar flare from Proxima Centauri is interesting because flares like these are problematic for habitability. Moreover, this one may tell us something about the nature of the planetary system around this star, making us rethink previous evidence for dust belts there.

But back to the habitability question. Can red dwarf stars sustain life in a habitable zone much closer to the primary than in our own Solar System, when they are subject to such violent outbursts? What we learn in a new paper from Meredith MacGregor and Alycia Weinberger (Carnegie Institution for Science) is that the flare at its peak on March 24, 2017 was 10 times brighter than the largest flares our G-class Sun produces at similar wavelengths (1.3 mm).

https://www.centauri-dreams.org/2018/02/27/proxima-flare-may-force-rethinking-of-dust-belts/

Offline hop

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Re: Pale Red Dot
« Reply #363 on: 04/09/2018 05:25 PM »
The First Naked-Eye Superflare Detected from Proxima Centauri

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Proxima b is a terrestrial-mass planet in the habitable-zone of Proxima Centauri. Proxima Centauri's high stellar activity however casts doubt on the habitability of Proxima b: sufficiently bright and frequent flares and any associated proton events may destroy the planet's ozone layer, allowing lethal levels of UV flux to reach its surface. In March 2016, the Evryscope observed the first naked-eye-visible superflare detected from Proxima Centauri. Proxima increased in brightness by a factor of ~68 during the superflare and released a bolometric energy of 10^33.5 erg, ~10X larger than any previously-detected flare from Proxima. Over the last two years the Evryscope has recorded 23 other large Proxima flares ranging in bolometric energy from 10^30.6 erg to 10^32.4 erg; coupling those rates with the single superflare detection, we predict at least five superflares occur each year. Simultaneous high-resolution HARPS spectroscopy during the Evryscope superflare constrains the superflare's UV spectrum and any associated coronal mass ejections. We use these results and the Evryscope flare rates to model the photochemical effects of NOx atmospheric species generated by particle events from this extreme stellar activity, and show that the repeated flaring is sufficient to reduce the ozone of an Earth-like atmosphere by 90% within five years. We estimate complete depletion occurs within several hundred kyr. The UV light produced by the Evryscope superflare therefore reached the surface with ~100X the intensity required to kill simple UV-hardy microorganisms, suggesting that life would struggle to survive in the areas of Proxima b exposed to these flares.
Edit:
Submitted, not yet reviewed, and the "naked eye" is a stretch. Undeniably a big flare through.
« Last Edit: 04/09/2018 06:01 PM by hop »

Offline Star One

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Re: Pale Red Dot
« Reply #364 on: 05/02/2018 07:48 PM »
TRAPPIST-1e Has a Large Iron Core

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The TRAPPIST-1 system provides an exquisite laboratory for understanding exoplanetary atmospheres and interiors. Their mutual gravitational interactions leads to transit timing variations, from which Grimm et al. (2018) recently measured the planetary masses with precisions ranging from 5% to 12%. Using these masses and the <5% radius measurements on each planet, we apply the method described in Suissa et al. (2018) to infer the minimum and maximum CRF (core radius fraction) of each planet. Further, we modify the maximum limit to account for the fact that a light volatile envelope is excluded for planets b through f. Only planet e is found to have a significant probability of having a non-zero minimum CRF, with a 0.7% false-alarm probability it has no core. Our method further allows us to measure the CRF of planet e to be greater than (49 +/- 7)% but less than (72 +/- 2)%, which is compatible with that of the Earth. TRAPPIST-1e therefore possess a large iron core similar to the Earth, in addition to being Earth-sized and located in the temperature zone.

https://arxiv.org/abs/1804.10618

Offline Alpha_Centauri

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Re: Pale Red Dot
« Reply #365 on: 07/07/2018 09:53 PM »
https://twitter.com/RedDotsSpace/status/1015712357392306176
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Attention #reddoters! New observing campaign starting today at HARPS @ESO. Updates on science work and follow-up opportunities to follow!
« Last Edit: 07/07/2018 09:53 PM by Alpha_Centauri »

Offline redliox

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Re: Pale Red Dot
« Reply #366 on: 07/08/2018 04:02 AM »
https://twitter.com/RedDotsSpace/status/1015712357392306176
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Attention #reddoters! New observing campaign starting today at HARPS @ESO. Updates on science work and follow-up opportunities to follow!

As the founder of this particular thread, I'm especially excited at a new study of Proxima!  ;D
"Let the trails lead where they may, I will follow."
-Tigatron

Offline Alpha_Centauri

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Re: Pale Red Dot
« Reply #367 on: 07/08/2018 11:36 AM »
Oh, maybe not including proxima this time;

https://twitter.com/RedDotsSpace/status/1015920018687750145
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Starting today to september 30th. New 3 targets : GJ 887 #10 nearest star-system, GJ 1061 #20, GJ 54.1 #21. Contributed observations welcome! @AAVSO call with details to be issued in short.

Offline ExoExplorer

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Re: Pale Red Dot
« Reply #368 on: 07/08/2018 02:43 PM »
Oh, maybe not including proxima this time;

https://twitter.com/RedDotsSpace/status/1015920018687750145
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Starting today to september 30th. New 3 targets : GJ 887 #10 nearest star-system, GJ 1061 #20, GJ 54.1 #21. Contributed observations welcome! @AAVSO call with details to be issued in short.
That's sort of good news to me. If the signal of proxima c is ambiguous (unable to confirm as planet or false positive), they wouldn't turn away to other targets.
« Last Edit: 07/08/2018 02:55 PM by ExoExplorer »

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