Alexandra Buldakova

Characteristics

Mass, radius, and temperature

The mass of Gliese 876 d from radial velocity has one problem, it is that only a lower limit on the mass can be obtained. This is because the measured mass value also depends on the orbital inclination, which in general is unknown. However, models incorporating the gravitational interactions between the resonant outer planets enables the inclination of the orbits to be determined. This reveals that the outer planets are nearly coplanar with an inclination of around 59° with respect to the plane of the sky. Assuming that Gliese 876 d orbits in the same plane as the other planets, the true mass of the planet is revealed to be 6.83 times the mass of Earth.[1]

The low mass of the planet has led to suggestions that it may be a terrestrial planet. This type of massive terrestrial planet could be formed in the inner part of the Gliese 876 system from material pushed towards the star by the inward migration of the gas giants.[2]

Alternatively the planet could have formed further from Gliese 876, as a gas giant, and migrated inwards with the other gas giants. This would result in a composition richer in volatile substances, such as water. As it arrived in range, the star would have blown off the planet's hydrogen layer via coronal mass ejection.[3] In this model, the planet would have a pressurised ocean of water (in the form of a supercritical fluid) separated from the silicate core by a layer of ice kept frozen by the high pressures in the planetary interior. Such a planet would have an atmosphere containing water vapor and free oxygen produced by the breakdown of water by ultraviolet radiation.[4]

Distinguishing between these two models would require more information about the planet's radius or composition. The planet does not transit its star,[5] which makes obtaining this information impossible with current observational capabilities.

Based on models, the radius of the exoplanet, based on the mass, can probably be estimated around 1.65 REarth.[citation needed]

The equilibrium temperature of Gliese 876 d, is estimated to be around 614 K (341 °C; 646 °F).[6]

Host star

The planet orbits a (M-type) star named Gliese 876. The star has a mass of 0.33 M☉ and a radius of around 0.36 R☉. It has a surface temperature of 3350 K and is 2.55 billion years old. In comparison, the Sun is about 4.6 billion years old[7] and has a surface temperature of 5778 K.[8]

Orbit

Gliese 876 d is located in an orbit with a semimajor axis of only 0.0208 AU (3.11 million km). At this distance from the star, tidal interactions should in theory circularize the orbit; however, measurements reveal that it has a high eccentricity of 0.207, comparable to that of Mercury in the Solar System.[1]

Models predict that, if its non-Keplerian orbit could be averaged to a Keplerian eccentricity of 0.28, then tidal heating would play a significant role in the planet's geology to the point of keeping it completely molten. Predicted total heat flux is approximately 104–5 W/m2 at the planet's surface; for comparison the surface heat flux for Io is around 3 W/m2.[9] This is similar to the radiative energy it receives from its parent star of about 40,000 W/m2.[note 1]

Discovery

Gliese 876 d was discovered by analysing changes in its star's radial velocity as a result of the planet's gravity. The radial velocity measurements were made by observing the Doppler shift in the star's spectral lines. At the time of discovery, Gliese 876 was known to host two extrasolar planets, designated Gliese 876 b and c, in a 2:1 orbital resonance. After the two planets were taken into account, the radial velocity still showed another period, at around two days. The planet, designated Gliese 876 d, was announced on June 13, 2005 by a team led by Eugenio Rivera and was estimated to have a mass approximately 7.5 times that of Earth.[5]

Physical characteristics

Mass, radius, and temperature

Due to it being discovered by the radial velocity method,[4] the only known physical parameter for Ross 128 b is its minimum possible mass. The planet is at least 1.35 MEarth, or 1.35 times the mass of Earth (about 8.06×1024 kg). This is slightly more massive than the similar and nearby Proxima Centauri b, with a minimum mass of 1.27 MEarth. The low mass of Ross 128 b implies that it is most likely a rocky Earth-sized planet with a solid surface.[citation needed] However, its radius, and therefore its density, is not known as no transits of this planet have been observed. Ross 128 b would be 0.5 REarth (Earth radii) for a pure-iron composition and 3.0 REarth for a pure hydrogen-helium composition, both implausible extremes. For a more plausible Earth-like composition, the planet would need to be about 1.10 REarth - i.e., 1.1 times the radius of Earth (approximately 7008 km). With that radius, Ross 128 b would be slightly denser than Earth, due to how a rocky planet would become more compact as it increases in size. It would give the planet a gravitational pull around 10.945 m/s2, or about 1.12 times that of Earth.[3]

Ross 128 b is calculated to have a temperature similar to that of Earth and potentially conducive to the development of life.[4] The discovery team modelled the planet's potential equilibrium temperature using albedos of 0.100, 0.367, and 0.750. Albedo is the portion of the light that is reflected instead of absorbed by a celestial object. With these three albedo parameters, Ross 128 b would have a Teq of either 294 K (21 °C; 70 °F), 269 K (−4 °C; 25 °F), or 213 K (−60 °C; −76 °F). For an Earth-like albedo of 0.3, the planet would have an equilibrium temperature of 280 K (7 °C; 44 °F), about 8 degrees Kelvin lower than Earth's average temperature.[4] The actual temperature of Ross 128 b depends on yet-unknown atmospheric parameters, if it has an atmosphere.[3]

In 2018, astronomers, based on near-infrared, high-resolution spectra (APOGEE Spectra), determined the chemical abundances of several elements (C, O, Mg, Al, K, Ca, Ti, and Fe) present in Ross 128 b, and further, that the exoplanet has near solar metallicity, contains a mixture of rock and iron and is a "temperate exoplanet in the inner edge of the habitable zone".[5][6]

Host star

Main article: Ross 128

File:Flying through the Ross 128 planetary system.webm

Artist's impression of Ross 128 b along with its red dwarf parent star

Ross 128 b orbits the small M-dwarf Ross 128. The star is 17% the mass and 20% the radius of that of the Sun. It has a temperature of 3192 K, a luminosity of 0.00362 L☉, and an age of 9.45±0.60 billion years. For comparison, the Sun has a temperature of 5772 K and age of 4.5 byr, making Ross 128 half the temperature and over twice the age. The star is only 11.03 light-years away, making it one of the 20 closest stars known.

Orbit

Ross 128 b is a closely orbiting planet, with a year (orbital period) lasting about 9.9 days.[3][4] Its semi-major axis is 0.0496 AU (7.42 million km). According to some models of the planet's orbit, its orbit is quite circular, with an eccentricity of around 0.03, but also with a large error range as well. However, if all the orbital models are brought together then the eccentricity is higher at about 0.116, and again this is subject to a large error range. Compared to the Earth's average distance from the Sun of 149 million km, Ross 128 b orbits 20 times closer. At that close distance from its host star, the planet is most likely tidally locked, meaning that one side of the planet would have eternal daylight and the other would be in darkness.[7][8]

Habitability

Main article: Habitability of red dwarf systems

Ross 128 b is not confirmed to be orbiting exactly within the habitable zone. It appears to reside within the inner edge, as it receives approximately 38% more sunlight than Earth. The habitable zone is defined as the region around a star where temperatures are just right for a planet with a thick enough atmosphere to support liquid water, a key ingredient in the development of life as we know it. With its moderately high stellar flux, Ross 128 b is likely more prone to water loss, mainly on the side directly facing the star. However, an Earth-like atmosphere, assuming one exists, would be able to distribute the energy received from the star around the planet and allow more areas to potentially hold liquid water.[9] In addition, study author Xavier Bonfils noted the possibility of significant cloud cover on the star-facing side, which would block out much incoming stellar energy and help keep the planet cool. It is calculated to have a temperature of at least 280 K.[citation needed]

The planet is considered one of the most Earth-like worlds ever found in relation to its temperature, size and rather quiet host star.[4] Ross 128 b is very close in mass to Earth, only about 35% more massive, and is likely around 10% larger in radius. Gravity on the planet would be only slightly higher. Also, its host star Ross 128 is an evolved star with a stable stellar activity.[4] Many red dwarfs like Proxima Centauri and TRAPPIST-1 are prone to releasing potentially deadly flares caused by powerful magnetic fields. Billions of years of exposure to these flares can potentially strip a planet of its atmosphere and render it sterile with possibly dangerous amounts of radiation. While Ross 128 is known to produce such flares, they are currently much less common and less powerful than those of the previously mentioned stars. This reduces the odds of atmospheric erosion (if Ross 128 b has one) and would increase the odds of its retention over geological timescales.[citation needed]

As of 2017, it is not yet possible to determine if Ross 128 b has an atmosphere because it does not transit the star.[4] However, upcoming missions like the James Webb Space Telescope and upcoming massive ground-based telescopes, like the Thirty Meter Telescope and the European Extremely Large Telescope, can potentially analyze the atmosphere of Ross 128 b - if it has one - without the need of a transit. This would enable scientists to find biosignatures in the planet's atmosphere, which are chemicals like oxygen, ozone, and methane that are often created by known biological processes.

Discovery

Velocity of Proxima Centauri towards and away from the Earth as measured with the HARPS spectrograph during the first three months of 2016. The red symbols with black error bars represent data points, and the blue curve is a fit of the data. The amplitude and period of the motion were used to estimate the planet's minimum mass.

Proxima Centauri had become a target for exoplanet searches already before the discovery of Proxima Centauri b, but initial studies in 2008 and 2009 ruled out the existence of larger-than-Earth exoplanets in the habitable zone.[4] Planets are very common around dwarf stars, with on average 1-2 planets per star,[5] and about 20-40% of all red dwarfs have one in the habitable zone.[6] Additionally, red dwarfs are by far the most common types of stars.[7]

Before 2016, observations with instruments[a] at the European Southern Observatory in Chile had identified anomalies in Proxima Centauri[8] which could not be satisfactorily be explained by flares[b] or chromospheric[c] activity of the star. Anglada-Escudé et al. 2016 proposed that an exoplanet in the habitable zone of Proxima Centauri could explain these anomalies.[11] In 2020, another planet Proxima Centauri c was discovered,[12] while the existence of a dust belt around Proxima Centauri and of a third planet were as of 2021 unconfirmed.[13] The discovery of Proxima Centauri b, a planet at habitable distances from the closest star to the Solar System, was a major discovery in planetology[14] and has drawn interest to the Alpha Centauri star system that Proxima is a member of.[15]

Physical properties

Proxima Centauri b is the closest exoplanet to Earth,[16] being at a distance of about 4.2 ly.[3] It orbits Proxima Centauri every 11.18427±0.00070 Earth days at a distance of 0.0485 au, [14] over 20 times closer to Proxima Centauri than Earth is to the Sun.[17] As of 2021 it is unclear if it actually has an eccentricity[d][20] but Proxima Centauri b is unlikely to have any obliquity.[21] The age of the planet is unknown;[22] Proxima Centauri itself may have been captured by Alpha Centauri and thus not necessarily of the same age as the latter, which are about 5 billion years old.[13] Proxima Centauri b is unlikely to have stable orbits for moons.[23]

As of 2020, the estimated minimum mass of Proxima Centauri b is 1.173±0.086 M🜨;[14] other estimates are similar[24] but all estimates are dependent on the inclination of the planet's orbit and may be underestimates.[13] This makes it similar to Earth, but the radius of the planet is poorly known and hard to determine[25] and the mass borders on the cutoff between Earth-type and Neptune-type planets.[5] Depending on the composition, Proxima Centauri b could either be a Mercury-like planet with a large core—which would require particular conditions early in the planet's history—to a very water-rich planet. Observations of the Fe-Si-Mg ratios of Proxima Centauri may allow a determination of the composition of the planet[26] since they are expected to roughly match these of the planets; various observations have found Solar System-like ratios of these elements.[27]

Relatively little is known about Proxima Centauri b as of 2021—mainly its distance from the star and its orbital period[28]—but a number of simulations of its properties have been made.[13] A number of simulations and models have been created that assume Earth-like compositions[29] and include predictions of the galactic environment, internal heat generation from radioactive decay and magnetic induction heating[e], planetary rotation, the effects of stellar radiation, the amount of volatile species the planet consists of and the changes of these parameters over time.[27]

Proxima Centauri b likely developed under different conditions than Earth, with less water, stronger impacts and an overall faster development assuming that it formed at its current distance from the star.[31] Proxima Centauri b probably did not form at its current distance to Proxima Centauri, as the amount of material in the protoplanetary disk would be insufficient. Instead, it or fragments formed at larger distances and then migrated to the current orbit of Proxima Centauri b. Depending on the nature of the precursor material, it may be rich in volatiles.[11] A number of different formation scenarios are possible, many of which depend on the existence of other planets around Proxima Centauri and which would result in different compositions.[32]

Tidal locking

Proxima Centauri b is likely to be tidally locked to the host star,[23] which for an 1:1 orbit would mean that the same side of the planet would always face Proxima Centauri.[22] It is unclear if habitable conditions can arise under such circumstances[33] as an 1:1 tidal lock would lead to an extreme climate with only part of the planet habitable.[22]

However, the planet may not be tidally locked. If the eccentricity of Proxima Centauri b was higher than 0.1[34]-0.06, it would tend to enter a Mercury-like 3:2 resonance[f] or higher-order resonances such as 2:1.[35] Additional planets around Proxima Centauri and interactions[g] with Alpha Centauri could excite higher eccentricies.[36] If the planet isn't symmetrical (triaxial), a capture into a non-tidally locked orbit would be possible even with low eccentricity.[37] A non-locked orbit however would result in tidal heating of the planet's mantle, increasing volcanic activity and potentially shutting down a magnetic field-generating dynamo.[38] The exact dynamics are strongly dependent on the internal structure of the planet and its evolution in response to tidal heating.[39]

Star

Main article: Proxima Centauri

Proxima Centauri is a red dwarf[35] with a mass equivalent to 0.120±0.015 solar masses and a radius of 0.141±0.021 solar radii. With an effective temperature[h] of 3050±100 kelvin, it has a spectral type[i] of M5.5V and a luminosity 0.00155±0.00006 of the Sun.[11] Proxima Centauri is a flare star and its luminosity varies by a factor of 100 over a timespan of hours.[42] The magnetic field of Proxima Centauri is considerably stronger than that of the Sun, with an intensity of 600±150 Gauss;[1] it varies in a 7-year long cycle.[43]

It is the closest star to the Sun[j], with a distance of 4.2426 ± 0.0020 light-years (1.3008 ± 0.0006 pc). Proxima Centauri is part of a multiple star system, whose other members are Alpha Centauri A and Alpha Centauri B which form a binary star subsystem.[44] The dynamics of the multiple star system could have caused Proxima Centauri b to move closer to its host star over its history.[45] The detection of a planet around Alpha Centauri in 2012 is considered questionable.[44] Despite its proximity to Earth, Proxima Centauri is too faint to be visible to the naked eye[4] with the exception of an instance where a flare made it visible to the naked eye.[46]

Surface conditions

Artist's conception of the surface of Proxima Centauri b. The Alpha Centauri AB binary system can be seen in the background, to the upper right of Proxima.

Proxima Centauri b is located within the classical habitable zone of its star;[47] it receives about 65% of Earth's irradiation. Its equilibrium temperature is about 234+6

−14 K.[11] Various factors, such as the orbital properties of Proxima Centauri b, the spectrum of radiation emitted by Proxima Centauri[k] and the behaviour of clouds[l] and hazes influence the climate of an atmosphere-bearing Proxima Centauri b.[52]

There are two likely scenarios for an atmosphere of Proxima Centauri b, one rich in oxygen and/or carbon dioxide if large amounts of water were converted to oxygen during the early phases of Proxima Centauri. and the hydrogen lost. Another when the planet initially featured a hydrogen-rich atmosphere or originated farther away from Proxima Centauri;[53] this would have reduced the escape of water and allowed it to persist on the planet.[45] If an atmosphere exists, it is likely to contain oxygen-bearing compounds such as oxygen and carbon dioxide. Together with the star's magnetic activity, they would give rise to aurorae that could be observed from Earth[54] if the planet has a magnetic field.[55]

Climate models including general circulation models used for Earth climate[56] have been used to simulate the properties of Proxima Centauri b's atmosphere. Depending on its properties such as whether it's tidally locked, the amount of water and carbon dioxide a number of scenarios are possible: Planets partially or wholly covered with ice, planet-wide or small oceans or only dry land, combinations between these[57] or scenarios with one or two "eyeballs"[m][59] or lobster-shaped areas with liquid water.[60] Additional factors are the nature of convection,[61] the distribution of continents, which can sustain a carbonate-silicate cycle and thus stabilize the atmospheric carbon dioxide concentrations,[62] ocean heat transport which broadens the space for habitable climates, salinity variations that alter the properties of an ocean,[59] the rotational period of the planet which determines Rossby wave dynamics[63] and sea ice dynamics which could cause a global ocean to freeze over.[64]

Stability of an atmosphere

The stability of an atmosphere is a major issue for the habitability of Proxima Centauri b:[65]

Strong irradiation by UV radiation and X-rays from Proxima Centauri constitutes a challenge to habitability.[16] Proxima Centauri b receives about 10-60 times as much of this radiation as Earth[47] with a particular increase in the X-rays[66] and might have received even more in the past,[67] adding up to 7-16 times as much cumulative XUV radiation than Earth.[68] UV radiation and X-rays can effectively evaporate an atmosphere[17] since hydrogen readily absorbs the radiation and does not readily lose it again, thus warming until the speed of hydrogen atoms and molecules is sufficient to escape from the gravitational field of a planet.[69] They can remove water by splitting it into hydrogen and oxygen and heating the hydrogen in the planet's exosphere until it escapes. The hydrogen can drag other elements such as oxygen[70] and nitrogen away.[71] Nitrogen and carbon dioxide can escape on their own from an atmosphere but this process is unlikely to substantially reduce the nitrogen and carbon dioxide content of an Earth-like planet.[72]

Stellar winds and coronal mass ejections are an even bigger threat to an atmosphere.[17] The amount of stellar wind impacting Proxima Centauri b may amount to 4-80 times that impacting Earth.[68] The more intense UV and X-rays radiation could lift the planet's atmosphere to outside of the magnetic field, increasing the loss triggered by stellar wind and mass ejections.[73]

At Proxima Centauri b's distance from the star, the stellar wind is likely to be denser than around Earth by a factor of 10-1000 depending on the strength of Proxima Centauri's magnetic field.[74] As of 2018 it is unknown whether the planet has a magnetic field[16] and the upper atmosphere may have its own magnetic field.[73] Depending on the intensity of Proxima Centauri b's magnetic field, it can penetrate deep into the atmosphere of the planet and strip parts of it off,[75] with substantial variability over daily and annual timescales.[74]

If the planet is tidally locked to the star, the atmosphere can collapse on the night side.[76] This is particularly a risk for a carbon dioxide-dominated atmosphere although carbon dioxide glaciers could recycle.[77]

Unlike Sun-like stars, Proxima Centauri's habitable zone would have been farther away early in the system's existence[78] when the star was in its pre-main sequence[n] stage.[79] In the case of Proxima Centauri, assuming that the planet formed in its current orbit it could have spent up to 180 million years too close to its star for water to condense.[45] Proxima Centauri b may therefore have suffered a Runaway greenhouse effect, in which the planet's water would have evaporated into steam,[80] which would then have been split into hydrogen and oxygen by UV radiation. The hydrogen and thus any water would have subsequently been lost,[45] similar to what is believed to have happened to Venus.[81]

While the characteristics of impact events on Proxima Centauri b are currently entirely conjectural, they could destabilize the atmospheres[82] and boil off oceans.[12]

Even if Proxima Centauri b lost its original atmosphere, volcanic activity could rebuild it after some time. A second atmosphere would likely contain carbon dioxide,[33] which would form a more stable atmosphere than an Earth-like atmosphere would be.[27] In the case of Earth, the amount of water contained within the mantle might approach that of one Earth ocean.[38] Additionally, impacts of exocomets could resupply water to Proxima Centauri b, if they are present.[83]

Delivery of water to Proxima Centauri b

A number of mechanisms can deliver water to a developing planet; how much water Proxima Centauri b received is unknown.[31] Modelling by Ribas et al. 2016 indicates that Proxima Centauri b would have lost no more than one Earth ocean equivalent of water[16] but later research suggested that the amount of water lost could be considerably larger[84] and Airapetian et al. 2017 concluded that an atmosphere would be lost within ten million years.[85] The estimates are strongly dependent on the initial mass of the atmosphere, however, and are thus highly uncertain.[38]

Life

See also: Habitability of red dwarf systems

In the context of exoplanet research, "habitability" is usually defined as the possibility that liquid water exists on the surface of a planet.[53] As normally understood in the context of exoplanet life, liquid water on the surface and an atmosphere are prerequisites for habitability—any life limited to the sub-surface of a planet,[78] such as in a subsurface ocean like in Europa in the Solar System, would be difficult to detect from afar[79] although it may constitute a model for life in a cold ocean-covered Proxima Centauri b.[86]

The habitability of red dwarfs is a controversial subject,[22] with a number of considerations:

Both the activity of Proxima Centauri and tidal locking would hinder the establishment of these conditions.[11]

Unlike XUV radiation, UV radiation on Proxima Centauri b is redder (colder) and thus may interact less with organic compounds[87] and may produce less ozone.[88] Conversely, stellar activity could deplete an ozone layer sufficiently to increase UV radiation to dangerous levels.[38][89]

Depending on its eccentricity, it may partially lie outside of the habitable zone during part of its orbit.[22]

Oxygen[90] and/or carbon monoxide may built up in the atmosphere of Proxima Centauri b to toxic quantities.[91] High oxygen concentrations may however aid in the evolution of complex organisms.[90]

If oceans are present, the tides could alternately flooding and drying coastal landscapes, triggering chemical reactions conducive to the development of life,[92] favour the evolution of biological rhythms such as the day-night cycle which otherwise would not develop in a tidally locked planet without a day-night cycle,[93] mix oceans and supply and redistribute nutrients[94] and stimulate periodic expansions of marine organisms such as red tides on Earth.[95]

On the other hand, red dwarfs like Proxima Centauri have a lifespan much longer than the Sun, up to many times the estimated age of the Universe, and thus give life plenty of time to develop.[96] The radiation emitted by Proxima Centauri is ill-suited for oxygen-generating photosynthesis but sufficient for anoxygenic photosynthesis[97] although it is unclear how life depending on anoxygenic photosynthesis could be detected.[98] One study in 2017 estimated that the productivity of a Proxima Centauri b ecosystem based on photosynthesis may be about 20% that of Earth's.[99]

Observation and exploration

As of 2021, Proxima Centauri b has not yet been directly imaged, as its separation from Proxima Centauri is too small for that.[100] It is unlikely[o] to transit Proxima Centauri from Earth's perspective.[101] The star is monitored for the possible emission of technology-related radio signals by the Breakthrough Listen project which in April-May 2019 detected the BLC1 signal; later investigations however indicated it is probably of human origin.[102]

Future large ground-based telescopes and space-based observatories such as the James Webb Space Telescope and the Wide-Field Infrared Survey Telescope could directly observe Proxima Centauri b, given its proximity to Earth,[17] but disentangling the planet from its star would be difficult.[33] Possible traits observable from Earth are the reflection of starlight from an ocean,[103] the radiative patterns of atmospheric gases and hazes[104] and of atmospheric heat transport[p].[105] Efforts have been done to determine how Proxima Centauri b would look like to Earth if it has particular properties such as atmospheres of a particular composition.[28]

Even the fastest spacecrafts build by humans would take a long time to travel interstellar distances; Voyager 2 would take about 75,000 years to reach Proxima Centauri. Among the proposed technologies to reach Proxima Centauri b in human lifespans are solar sails that could reach speeds of 20% the speed of light; problems would be how to decelerate a probe when it arrives in the Proxima Centauri system and collisions of the high-speed probes with interstellar particles. Among the projects of travelling to Proxima Centauri b are the Breakthrough Starshot project, which aims to develop instruments and power systems that can reach Proxima Centauri in the 21st century.

Texas Hold'em, sometimes called simply Hold'em— is the most popular type of poker today, a game with two pocket and five community cards used by all players when making combinations (a kind of so-called community poker).

History

Johnny Moss, Chill Wills, Amarillo Slim, Jack Binion, Puggy Pearson outside Binion's Horseshoe Casino in 1974

The town of Robstown in Texas is considered to be the official place of the appearance of hold'em.

After the advent of hold'em and its spread across Texas in 1967, the game appeared in Las Vegas. The game was brought to Las Vegas by such famous Texas players as Doyle Brunson, Amarillo Slim and Pretzel Addington.

Addington said that he first saw how hold'em was played in the late 60s. At that time, the game was not yet called Texas Hold'em, but simply Hold'em.

Texas Hold'em was later brought to Europe by Liam Flood and Terry Rogers.

For several years, this game could only be played at the only casino in Vegas — the Golden Nugget Casino.

Game progress

References to sources

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Check the information.

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There should be explanations on the discussion page.

The game goes as follows:

In some games, all players make a small initial contribution (ante): this increases the size of the pot (the total money on the table) and the activity of the players.

Two players sitting behind the dealer (button, dealer) place blind bets (blinds). Usually, the first one makes half of the minimum bet (small blind), and the second one makes the whole bet (big blind).

Each player receives two cards, in a closed (preflop), a trading circle follows.

Three cards are placed on the table in front of all players, in the open (flop), a trading circle follows.

The fourth card is placed on the table in the open (turn), followed by a trading circle. When playing Limited Hold'em, the fixed bet doubles at this point.

The fifth card is placed on the table, in the open (river). Thus, there are 5 cards on the table, the last round of trading follows.

The goal of the game is to make the best combination by combining any five cards out of seven: five common and two of their own. That is, you can use two, one or none of your cards.

During each trading round, players can perform one of the following actions:

Place a bet (bet). The player who is to the left of the dealer makes the first bet, and he sets the minimum bet in this trading circle.

Equalize the bet (call). Agree with the previous player's bet.

Raise the bet (raise). Bet more than the previous player.

Pass the move (check). You can only do this if there has not been a bet in this trading circle yet.

Exit the game (fold). Fold the cards and lose the money already wagered.

Combinations

To win, a player must either use bidding (betting) to force opponents to throw off cards, or collect a winning combination. The pot of the hand is taken by the player who has the highest combination at the end of the game. You can form a combination of 5 open cards on the board and two cards closed from other players in your hands.

Seniority of combinations in ascending order:

Kicker. The highest card.

Couple. Two cards of the same value.

Two pairs. Two cards of one value, two cards of another value.

Set. Three cards of the same value.

Street. Five cards that are lined up by seniority.

Flash. Five cards of the same suit.

Full house. Three plus two.

Square. Four cards of the same value.

Straight flush. Five cards of the same suit, which are lined up by seniority.

Royal flush. Five cards from 10 to ace of the same suit.

Varieties

There are three main types of Texas Hold 'em:

limited - bets are limited.

with a pot limit — the maximum bet is limited by the size of the bank;

unlimited - the maximum bet is limited by the size of the player's stack.

Casino Hold'em

Casino-hold'em (Eng. Casino Holdem Poker) is a series of poker games against casinos based on Texas Hold'em. A common feature of these games is that the player and the dealer are dealt two pocket cards each, and five cards are put on the table together. The goal of the games is to collect the largest poker combination of 5 cards using your 2 cards and 5 community cards.

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PokerKing Royal Club - PokerKing loyalty program. It has 5 levels. The simplest level ("Bronze") gives 10% cashback, and the highest ("Royal") gives 40% cashback.

RuTracker.org (previously — Torrents.ru ) is the largest Russian-language BitTorrent tracker with more than 13.74 million registered accounts. More than 2.141 million hands have been registered on the tracker (of which more than 1.975 million are "live"), the total size of the tracker's hands is 4,537 petabytes (as of November 30, 2021). Domain name — rutracker.org, in Russia is included in the list of banned sites after the decision of the Moscow City Court. The court decided to block the torrent tracker on December 4, 2015 on the joint claim of the publishing houses "Eksmo" and "S. B. A. Production", which is a subsidiary of the record company Warner Music Russia.

The National Research University "Higher School of Economics" is a research university that carries out its mission through scientific and educational, project, expert-analytical and socio-cultural activities based on international scientific and organizational standards. We are aware of ourselves as part of the global academic community, and we consider international partnership and involvement in global university interaction to be key elements of our progress. As a Russian university, we work for the benefit of Russia and its citizens. Our university is a team of scientists, staff, graduate students and students who are distinguished by an internal commitment to maintaining high academic standards of their activities. We strive to provide the most favorable conditions for the development of each member of our team.