Author Topic: Possible first discovered exomoon  (Read 2148 times)

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Offline Toliman

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Re: Possible first discovered exomoon
« Reply #20 on: December 16, 2019, 06:04:58 am »
A bit older but still interesting:

Scientists may have found a fiery exomoon that's like a volcanic planet from 'Star Wars'
https://edition.cnn.com/2019/09/05/world/exomoon-volcanoes-star-wars-scn/index.html

Although thousands of exoplanets have been discovered outside our solar system since the 1990s, astronomers are still hunting for something that remains elusive there: exomoons.
Over the last year, a few researchers have suggested potential evidence for locating these small moons around exoplanets, but nothing has been confirmed.

Now, researchers believe they have found possible indications of an exomoon orbiting a giant, scorching exoplanet in the Lepus constellation, 550 light-years from Earth. And it's comparable to Mustafar, a small volcanic planet sandwiched between two gas giants where Anakin Skywalker undergoes his dark, painful transition into Darth Vader in "Star Wars: Episode III -- Revenge of the Sith."

"It would be a dangerous volcanic world with a molten surface of lava, a place where Jedis go to die, perilously familiar to Anakin Skywalker," said Apurva Oza, study author and postdoctoral fellow at the Physics Institute of the University of Bern.
The WASP 49-b exoplanet system includes a gas giant that completes one orbit around its star every three days. The planet was discovered orbiting the WASP 49 star in 2012 via the transit method, which is when an exoplanet passes in front of its star, causing detectable dips in starlight.

Offline Toliman

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Re: Possible first discovered exomoon
« Reply #21 on: February 04, 2020, 06:08:13 pm »
Radial velocity constraints on the long-period transiting planet Kepler-1625 b with CARMENES
https://arxiv.org/abs/2001.10867

The star Kepler-1625 recently attracted considerable attention when an analysis of the stellar photometric time series from the Kepler mission was interpreted as showing evidence of a large exomoon around the transiting Jupiter-sized planet candidate Kepler-1625b. We aim to detect the radial velocity (RV) signal imposed by Kepler-1625b (and its putative moon) on the host star or, as the case may be, determine an upper limit on the mass of the transiting object. We took a total of 22 spectra of Kepler-1625 using CARMENES, 20 of which were useful. Observations were spread over a total of seven nights between October 2017 and October 2018, covering 125% of one full orbit of Kepler-1625b. We used the automatic Spectral Radial Velocity Analyser (SERVAL) pipeline to deduce the stellar RVs and uncertainties. Then we fitted the RV curve model of a single planet on a Keplerian orbit to the observed RVs using a χ2 minimisation procedure. We derive upper limits on the mass of Kepler-1625b under the assumption of a single planet on a circular orbit. In this scenario, the 1σ, 2σ, and 3σ confidence upper limits for the mass of Kepler-1625b are 2.90MJ, 7.15MJ, and 11.60MJ, respectively. We present strong evidence for the planetary nature of Kepler-1625b, making it the 10th most long-period confirmed planet known today. Our data does not answer the question about a second, possibly more short-period planet that could be responsible for the observed transit timing variation of Kepler-1625b.

Offline Toliman

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Re: Possible first discovered exomoon
« Reply #22 on: April 11, 2020, 05:00:09 pm »
The Subsurface Habitability Of Small, Icy Exomoons
http://astrobiology.com/2020/03/the-subsurface-habitability-of-small-icy-exomoons.html

Assuming our Solar System as typical, exomoons may outnumber exoplanets. If their habitability fraction is similar, they would thus constitute the largest portion of habitable real estate in the Universe.

Icy moons in our Solar System, such as Europa and Enceladus, have already been shown to possess liquid water, a prerequisite for life on Earth.

We intend to investigate under what circumstances small, icy moons may sustain subsurface oceans and thus be "subsurface habitable". We pay specific attention to tidal heating. We made use of a phenomenological approach to tidal heating. We computed the orbit averaged flux from both stellar and planetary (both thermal and reflected stellar) illumination. We then calculated subsurface temperatures depending on illumination and thermal conduction to the surface through the ice shell and an insulating layer of regolith. We adopted a conduction only model, ignoring volcanism and ice shell convection as an outlet for internal heat.

In doing so, we determined at which depth, if any, ice melts and a subsurface ocean forms. We find an analytical expression between the moon's physical and orbital characteristics and the melting depth. Since this expression directly relates icy moon observables to the melting depth, it allows us to swiftly put an upper limit on the melting depth for any given moon. We reproduce the existence of Enceladus' subsurface ocean; we also find that the two largest moons of Uranus (Titania & Oberon) could well sustain them. Our model predicts that Rhea does not have liquid water.

Habitable exomoon environments may be found across an exoplanetary system, largely irrespective of the distance to the host star. Small, icy subsurface habitable moons may exist anywhere beyond the snow line. This may, in future observations, expand the search area for extraterrestrial habitable environments beyond the circumstellar habitable zone.

https://arxiv.org/pdf/2003.09231.pdf

Offline archaic

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Re: Possible first discovered exomoon
« Reply #23 on: May 07, 2020, 04:25:17 pm »
This is exciting, thank you for posting!  :D  :D
Pasha, an Avatar story, my current fanfic, Avatar related.

The Dragon Affair my last fanfic, non Avatar related.

Offline Toliman

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Re: Possible first discovered exomoon
« Reply #24 on: May 07, 2020, 05:06:21 pm »
Kea tìkin :)

Yeah, there news from exomoons research are very exciting for me!

Offline Toliman

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Re: Possible first discovered exomoon
« Reply #25 on: May 15, 2020, 07:01:14 am »
Orbital Stability of Exomoons and Submoons with Applications to Kepler 1625b-I
https://arxiv.org/pdf/2005.06521.pdf

An intriguing question in the context of dynamics arises: Could a moon possess a moon itself? Such a configuration does not exist in the Solar System, although this may be possible in theory. Kollmeier & Raymond (2019) determined the critical size of a satellite necessary to host a long-lived sub-satellite, or submoon. However, the orbital constraints for these submoons to exist are still undetermined. Domingos et al. (2006) indicated that moons are stable out to a fraction of the host planets Hill radius RH,p, which in turn depend on the eccentricity of its host’s orbit. Motivated by this, we simulate systems of exomoons and submoons for 105 planetary orbits, while considering many initial orbital phases to obtain the critical semimajor axis in terms of RH,p or the host satellite’s Hill radius RH,sat, respectively. We find that, assuming circular coplanar orbits, the stability limit for an exomoon is 0.40 RH,p and for a submoon is 0.33 RH,sat. Additionally, we discuss the observational feasibility of detecting these sub-satellites through photometric, radial velocity, or direct imaging observations using the Neptune-sized exomoon candidate Kepler 1625b-I (Teachey & Kipping 2018) and identify how stability can shape the identification of future candidates.

Quote
An intriguing question in the context of dynamics arises: Could a moon possess a moon itself? Such a configuration does not exist in the Solar System, although this may be possible in theory. ...
Well, it start be too crazy even for me... ;D But interesting idea, eltur tìtxen si nìngay :)


« Last Edit: May 15, 2020, 07:12:36 am by Toliman »

Offline Toliman

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Re: Possible first discovered exomoon
« Reply #26 on: June 12, 2020, 03:02:20 pm »
Exploring formation scenarios for the exomoon candidate Kepler 1625b I
https://arxiv.org/pdf/2005.10138.pdf

If confirmed, the Neptune-size exomoon candidate in the Kepler 1625 system will be the first natural satellite outside our Solar System. Its characteristics are nothing alike we know for a satellite. Kepler 1625b I is expected to be as massive as Neptune and to orbit at 40 planetary radii around a ten Jupiter mass planet. Because of its mass and wide orbit, this satellite was firstly thought to be captured instead of formed in-situ. In this work, we investigated the possibility of an in-situ formation of this exomoon candidate. To do so, we performed N-body simulations to reproduce the late phases of satellite formation and use a massive circum-planetary disc to explain the mass of this satellite. Our setups started soon after the gaseous nebula dissipation, when the satellite embryos are already formed. Also for selected exomoon systems we take into account a post-formation tidal evolution. We found that in-situ formation is viable to explain the origin of Kepler 1625b I, even when different values for the starplanet separation are considered. We show that for different star-planet separations the minimum amount of solids needed in the circum-planetary disc to form such a satellite varies, the wider is this separation more material is needed. In our simulations of satellite formation many satellites were formed close to the planet, this scenario changed after the tidal evolution of the systems. We concluded that if the Kepler1625 b satellite system was formed in-situ, tidal evolution was an important mechanism to sculpt its final architecture.

Offline Toliman

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Re: Possible first discovered exomoon
« Reply #27 on: July 18, 2020, 02:01:29 pm »
Impact of Tides on the Potential for Exoplanets to Host Exomoons
https://arxiv.org/pdf/2007.01487.pdf

Exomoons may play an important role in determining the habitability of worlds outside of our solar system. They can stabilize conditions, alter the climate by breaking tidal locking with the parent star, drive tidal heating, and perhaps even host life themselves. However, the ability of an exoplanet to sustain an exomoon depends on complex tidal interactions. Motivated by this, we make use of simplified tidal lag models to follow the evolution of the separations and orbital and rotational periods in planet, star, and moon systems. We apply these models to known exoplanet systems to assess the potential for these exoplanets to host exomoons. We find that there are at least 36 systems in which an exoplanet in the habitable zone may host an exomoon for longer than one gigayear. This includes Kepler-1625b, an exoplanet with an exomoon candidate, which we determine would be able to retain a Neptune-sized moon for longer than a Hubble time. These results may help provide potential targets for future observation. In many cases, there remains considerable uncertainty in the composition of specific exoplanets. We show the detection (or not) of an exomoon would provide an important constraint on the planet structure due to differences in their tidal response.

Offline Toliman

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Re: Possible first discovered exomoon
« Reply #28 on: August 03, 2020, 09:54:09 am »
Astronomers discover 6 possible new exomoons
https://earthsky.org/space/astronomers-discover-6-possible-new-exomoons

Astronomers from Western University in Canada have discovered six more possible exomoons orbiting distant exoplanets, in data from the Kepler Space Telescope.

 

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