NGTS Results

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NGTS Results

Post by Sirius_Alpha on 30th October 2017, 9:05 pm

A hot Jupiter around an M dwarf makes its debut as the NGTS's first extrasolar planet discovery!

NGTS-1b: A hot Jupiter transiting an M-dwarf
https://arxiv.org/abs/1710.11099

We present the discovery of NGTS-1b, a hot-Jupiter transiting an early M-dwarf host (Teff=3916+71−63 K) in a P=2.674d orbit discovered as part of the Next Generation Transit Survey (NGTS). The planet has a mass of 0.812+0.066−0.075 MJ, making it the most massive planet ever discovered transiting an M-dwarf. The radius of the planet is 1.33+0.61−0.33 RJ. Since the transit is grazing, we determine this radius by modelling the data and placing a prior on the density from the population of known gas giant planets. NGTS-1b is the third transiting giant planet found around an M-dwarf, reinforcing the notion that close-in gas giants can form and migrate similar to the known population of hot Jupiters around solar type stars. The host star shows no signs of activity, and the kinematics hint at the star being from the thick disk population. With a deep (2.5%) transit around a K=11.9 host, NGTS-1b will be a strong candidate to probe giant planet composition around M-dwarfs via JWST transmission spectroscopy.

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Re: NGTS Results

Post by Lazarus on 31st October 2017, 4:56 am

There's also a paper up describing the details of NGTS

Wheatley et al. "The Next Generation Transit Survey (NGTS)"
https://arxiv.org/abs/1710.11100
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Re: NGTS Results

Post by Led_Zep on 31st October 2017, 3:53 pm

Two links about NGTS-1b :

https://warwick.ac.uk/newsandevents/pressreleases/monster_planet_discovery/
Monster’ planet discovery challenges formation theory


http://www.eso.org/public/announcements/ann17076/
New Exoplanet Survey Finds its First Planet
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Re: NGTS Results

Post by Edasich on 1st November 2017, 10:16 am

I remember similar transiting objects detected long time ago, SWEEPS-02 b, SWEEPS-10 b and SWEEPS-15 b (no mass estimate though, radius only), some with ultrashort orbital period (e.g. SWEEPS-10 b, 0.424 days). Discovery dates back 2006 but as far as I know there hasn't been any update since, neither confirmation or disproval.
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Re: NGTS Results

Post by Lazarus on 1st November 2017, 7:52 pm

It's pretty unlikely that there will be any follow-up on the SWEEPS candidates, the distance makes observations difficult and there is more value in observing nearer systems which are more amenable for transit spectroscopy etc.
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Re: NGTS Results

Post by Sirius_Alpha on 3rd May 2018, 9:00 pm

Unmasking the hidden NGTS-3Ab: a hot Jupiter in an unresolved binary system
https://arxiv.org/abs/1805.01378

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Re: NGTS Results

Post by Edasich on 4th May 2018, 4:32 am

Sirius_Alpha wrote:Unmasking the hidden NGTS-3Ab: a hot Jupiter in an unresolved binary system
https://arxiv.org/abs/1805.01378

Nice find. Waiting for the NGTS-2 b too pops up sooner or later. Wink
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Re: NGTS Results

Post by Lazarus on 4th May 2018, 3:49 pm

The discussion is worth a read, particularly the section "NGTS-3 as a cautionary tale of careful vetting".
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Re: NGTS Results

Post by Sirius_Alpha on 28th May 2018, 8:48 pm

NGTS-2b: An inflated hot-Jupiter transiting a bright F-dwarf
https://arxiv.org/abs/1805.10449

We report the discovery of NGTS-2b, an inflated hot-Jupiter transiting a bright F5V star (Teff=6478+94−89 K), discovered as part of the Next Generation Transit Survey (NGTS). The planet is in a P=4.51 day orbit with mass 0.74+0.13−0.12 MJ, radius 1.595+0.047−0.045 RJ and density 0.226+0.040−0.038 g cm−3; therefore one of the lowest density exoplanets currently known. With a relatively deep 1.0% transit around a bright V=10.96 host star, NGTS-2b is a prime target for probing giant planet composition via atmospheric transmission spectroscopy. The rapid rotation (vsini=15.2±0.8 km s−1) also makes this system an excellent candidate for Rossiter-McLaughlin follow-up observations, to measure the sky-projected stellar obliquity. NGTS-2b was confirmed without the need for follow-up photometry, due to the high precision of the NGTS photometry.

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Re: NGTS Results

Post by Sirius_Alpha on 4th September 2018, 10:50 pm

NGTS-4b: A sub-Neptune Transiting in the Desert
https://arxiv.org/abs/1809.00678

We report the discovery of NGTS-4b, a sub-Neptune-sized planet transiting a 13th magnitude K-dwarf in a 1.34d orbit. NGTS-4b has a mass M=20.6±3.0M_E and radius R=3.18±0.26R_E, which places it well within the so-called "Neptunian Desert". The mean density of the planet (3.45±0.95g/cm^3) is consistent with a composition of 100% H2O or a rocky core with a volatile envelope. NGTS-4b is likely to suffer significant mass loss due to relatively strong EUV/X-ray irradiation. Its survival in the Neptunian desert may be due to an unusually high core mass, or it may have avoided the most intense X-ray irradiation by migrating after the initial activity of its host star had subsided. With a transit depth of 0.13±0.02%, NGTS-4b represents the shallowest transiting system ever discovered from the ground, and is the smallest planet discovered in a wide-field ground-based photometric survey.

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