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44-562: (Redirected from Kepler Star ) Kepler star may refer to: Kepler Object of Interest , a star observed by the Kepler spacecraft which is suspected of hosting one or more transiting planets Kepler's Supernova , a supernova that occurred in the Milky Way, observed by the naked eye in 1604 Small or great stellated dodecahedron, geometric solids; see Kepler–Poinsot polyhedron Topics referred to by

88-441: A specific range of frequencies . The audible frequency range for humans is typically given as being between about 20 Hz and 20,000 Hz (20 kHz), though the high frequency limit usually reduces with age. Other species have different hearing ranges. For example, some dog breeds can perceive vibrations up to 60,000 Hz. In many media, such as air, the speed of sound is approximately independent of frequency, so

132-411: A fractional error of Δ f f = 1 2 f T m {\textstyle {\frac {\Delta f}{f}}={\frac {1}{2fT_{\text{m}}}}} where T m {\displaystyle T_{\text{m}}} is the timing interval and f {\displaystyle f} is the measured frequency. This error decreases with frequency, so it

176-478: A heart beats at a frequency of 120 times per minute (2 hertz), the period—the time interval between beats—is half a second (60 seconds divided by 120). For cyclical phenomena such as oscillations , waves , or for examples of simple harmonic motion , the term frequency is defined as the number of cycles or repetitions per unit of time. The conventional symbol for frequency is f or ν (the Greek letter nu )

220-416: A known frequency near the unknown frequency is mixed with the unknown frequency in a nonlinear mixing device such as a diode . This creates a heterodyne or "beat" signal at the difference between the two frequencies. If the two signals are close together in frequency the heterodyne is low enough to be measured by a frequency counter. This process only measures the difference between the unknown frequency and

264-401: A list of KOIs was on 15 June 2010 and contained 306 stars suspected of hosting exoplanets , based on observations taken between 2 May 2009 and 16 September 2009. It was also announced that an additional 400 KOIs had been discovered, but would not be immediately released to the public. This was done in order for follow-up observations to be performed by Kepler team members. On February 1, 2011,

308-402: A repeating event is accomplished by counting the number of times that event occurs within a specific time period, then dividing the count by the period. For example, if 71 events occur within 15 seconds the frequency is: f = 71 15 s ≈ 4.73 Hz . {\displaystyle f={\frac {71}{15\,{\text{s}}}}\approx 4.73\,{\text{Hz}}.} If

352-484: A second release of observations made during the same time frame contained improved date reduction and listed 1235 transit signals around 997 stars. Stars observed by Kepler that are considered candidates for transit events are given the designation "KOI" followed by an integer number. For each set of periodic transit events associated with a particular KOI, a two-digit decimal is added to the KOI number for that star. For example,

396-405: A transiting white dwarf, but this is actually a transiting brown dwarf known as LHS 6343 C. KOI-54 is believed to be a binary system containing two A-class stars in highly eccentric orbits with a semi-major axis of 0.4 AU . During periastron , tidal distortions cause a periodic brightening of the system. In addition, these tidal forces induce resonant pulsations in one (or both) of

440-435: Is also used. The period T is the time taken to complete one cycle of an oscillation or rotation. The frequency and the period are related by the equation f = 1 T . {\displaystyle f={\frac {1}{T}}.} The term temporal frequency is used to emphasise that the frequency is characterised by the number of occurrences of a repeating event per unit time. The SI unit of frequency

484-495: Is called a radio wave . Likewise, an electromagnetic wave with a frequency higher than 8 × 10  Hz will also be invisible to the human eye; such waves are called ultraviolet (UV) radiation. Even higher-frequency waves are called X-rays , and higher still are gamma rays . All of these waves, from the lowest-frequency radio waves to the highest-frequency gamma rays, are fundamentally the same, and they are all called electromagnetic radiation . They all travel through vacuum at

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528-612: Is different from Wikidata All article disambiguation pages All disambiguation pages Kepler Object of Interest The Kepler mission lasted for 4 years from 2009 to 2013. The K2 mission continued the mission for next 5 years and ended in October 2018. The KOI provides a catalogue of 10,000 astronomical bodies and many of those have been confirmed as exoplanets. The KOI numbers are not going to increase and with advanced technology telescopes, KOIs could become confirmed exoplanets faster than before. The first public release of

572-411: Is generally a problem at low frequencies where the number of counts N is small. An old method of measuring the frequency of rotating or vibrating objects is to use a stroboscope . This is an intense repetitively flashing light ( strobe light ) whose frequency can be adjusted with a calibrated timing circuit. The strobe light is pointed at the rotating object and the frequency adjusted up and down. When

616-471: Is in fact much larger and hotter than first reported. For now, the only transiting "Earth-like" candidate in the habitable zone around a sun-like star is KOI-456.04 , which is in orbit around Kepler-160. A September 2011 study by Muirhead et al. reports that a re-calibration of estimated radii and effective temperatures of several dwarf stars in the Kepler sample yields six new terrestrial-sized candidates within

660-402: Is red light, 800 THz ( 8 × 10  Hz ) is violet light, and between these (in the range 400–800 THz) are all the other colors of the visible spectrum . An electromagnetic wave with a frequency less than 4 × 10  Hz will be invisible to the human eye; such waves are called infrared (IR) radiation. At even lower frequency, the wave is called a microwave , and at still lower frequencies it

704-476: Is related to angular frequency (symbol ω , with SI unit radian per second) by a factor of 2 π . The period (symbol T ) is the interval of time between events, so the period is the reciprocal of the frequency: T = 1/ f . Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio signals ( sound ), radio waves , and light . For example, if

748-493: Is termed rotational frequency , is revolution per minute , abbreviated r/min or rpm. 60 rpm is equivalent to one hertz. As a matter of convenience, longer and slower waves, such as ocean surface waves , are more typically described by wave period rather than frequency. Short and fast waves, like audio and radio, are usually described by their frequency. Some commonly used conversions are listed below: For periodic waves in nondispersive media (that is, media in which

792-617: Is the hertz (Hz), named after the German physicist Heinrich Hertz by the International Electrotechnical Commission in 1930. It was adopted by the CGPM (Conférence générale des poids et mesures) in 1960, officially replacing the previous name, cycle per second (cps). The SI unit for the period, as for all measurements of time, is the second . A traditional unit of frequency used with rotating mechanical devices, where it

836-400: Is the speed of light in vacuum, and this expression becomes f = c λ . {\displaystyle f={\frac {c}{\lambda }}.} When monochromatic waves travel from one medium to another, their frequency remains the same—only their wavelength and speed change. Measurement of frequency can be done in the following ways: Calculating the frequency of

880-745: The Kepler space telescope's field of view have been identified by the mission as Kepler-1, Kepler-2, and Kepler-3 and have planets which were previously known from ground based observations and which were re-observed by Kepler. These stars are cataloged as GSC 03549-02811 , HAT-P-7 , and HAT-P-11 . Eight stars were first observed by Kepler to have signals indicative of transiting planets and have since had their nature confirmed. These stars are: Kepler-1658 , KOI-5 , Kepler-4 , Kepler-5 , Kepler-6 , Kepler-7 , Kepler-8 , Kepler-9 , Kepler-10 , and Kepler-11 . Of these, Kepler-9 and Kepler-11 have multiple planets (3 and 6, respectively) confirmed to be orbiting them. Kepler-1658b (KOI-4.01) orbiting Kepler-1658

924-486: The alternating current in household electrical outlets is 60 Hz (between the tones B ♭ and B; that is, a minor third above the European frequency). The frequency of the ' hum ' in an audio recording can show in which of these general regions the recording was made. Aperiodic frequency is the rate of incidence or occurrence of non- cyclic phenomena, including random processes such as radioactive decay . It

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968-403: The depth of the signal, the duration of the signal and the periodicity of the signal (although some signals lack this last piece of information). Assuming the signal is due to a planet, these data can be used to obtain the size of the planet relative to its host star, the planet's distance from the host star relative to the host star's size (assuming zero eccentricity ), and the orbital period of

1012-405: The first transit event candidate identified around the star KOI-718 is designated KOI-718.01 , while the second candidate is KOI-718.02 and the third is KOI-718.03 . Once a transit candidate is verified to be a planet (see below), the star is designated "Kepler" followed by a hyphen and an integer number. The associated planet(s) have the same designation, followed by a letter in the order each

1056-477: The foreground KOI, are too close to the KOI on the sky for the Kepler telescope to differentiate. On the other hand, statistical fluctuations in the data are expected to contribute less than one false positive event in the entire set of 150,000 stars being observed by Kepler. In addition to false positives, a transit signal can be due to a planet that is substantially larger than what is estimated by Kepler. This occurs when there are sources of light other than simply

1100-421: The frequency of the strobe equals the frequency of the rotating or vibrating object, the object completes one cycle of oscillation and returns to its original position between the flashes of light, so when illuminated by the strobe the object appears stationary. Then the frequency can be read from the calibrated readout on the stroboscope. A downside of this method is that an object rotating at an integer multiple of

1144-410: The habitable zones of their stars: KOI-463.01 , KOI-1422.02 , KOI-947.01 , KOI-812.03 , KOI-448.02 , KOI-1361.01 . [1] Several KOIs contain transiting objects which are hotter than the stars they transit, indicating that the smaller objects are white dwarfs formed through mass transfer . These objects include KOI-74 and KOI-81 . A 2011 list of Kepler candidates also lists KOI-959 as hosting

1188-446: The likelihood of background eclipsing binaries. Such follow-up observations are estimated to reduce the chance of such background objects to less than 0.01%. Additionally, spectra of the KOIs can be taken to see if the star is part of a binary system. As of August 10, 2016, Kepler had found 2329 confirmed planets orbiting 1647 stars, as well as 4696 planet candidates. Three stars within

1232-532: The low mass stars 2 of only 4 known fully convective stars to have accurate determinations of their parameters (i.e. to better than several percent). The other 2 stars constitute the eclipsing binary system CM Draconis . Frequency Frequency (symbol f ), most often measured in hertz (symbol: Hz), is the number of occurrences of a repeating event per unit of time . It is also occasionally referred to as temporal frequency for clarity and to distinguish it from spatial frequency . Ordinary frequency

1276-533: The nature deduced by Kepler (and not a false positive or misidentification) has been estimated at >80%. Six transit signals released in the February 1, 2011 data are indicative of planets that are both "Earth-like" (less than 2 Earth radii in size) and located within the habitable zone of the host star. They are: KOI-456.04 , KOI-1026.01 , KOI-854.01 , KOI-701.03 , KOI 326.01 , and KOI 70.03 . A more recent study found that one of these candidates ( KOI-326.01 )

1320-509: The nature of any given planet candidate. Additional observations are necessary in order to confirm that a KOI actually has the planet that has been predicted, instead of being a false positive or misidentification. The most well-established confirmation method is to obtain radial velocity measurements of the planet acting on the KOI. However, for many KOIs this is not feasible. In these cases, speckle imaging or adaptive optics imaging using ground-based telescopes can be used to greatly reduce

1364-545: The number of counts is not very large, it is more accurate to measure the time interval for a predetermined number of occurrences, rather than the number of occurrences within a specified time. The latter method introduces a random error into the count of between zero and one count, so on average half a count. This is called gating error and causes an average error in the calculated frequency of Δ f = 1 2 T m {\textstyle \Delta f={\frac {1}{2T_{\text{m}}}}} , or

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1408-543: The planet. Combined with the estimated properties of the star described previously, estimates on the absolute size of the planet, its distance from the host star and its equilibrium temperature can be made. While it has been estimated that 90% of the KOI transit candidates are true planets, it is expected that some of the KOIs will be false positives , i.e., not actual transiting planets. The majority of these false positives are anticipated to be eclipsing binaries which, while spatially much more distant and thus dimmer than

1452-410: The reference frequency. To convert higher frequencies, several stages of heterodyning can be used. Current research is extending this method to infrared and light frequencies ( optical heterodyne detection ). Visible light is an electromagnetic wave , consisting of oscillating electric and magnetic fields traveling through space. The frequency of the wave determines its color: 400 THz ( 4 × 10 Hz)

1496-560: The rotation rate of a shaft, mechanical vibrations, or sound waves , can be converted to a repetitive electronic signal by transducers and the signal applied to a frequency counter. As of 2018, frequency counters can cover the range up to about 100 GHz. This represents the limit of direct counting methods; frequencies above this must be measured by indirect methods. Above the range of frequency counters, frequencies of electromagnetic signals are often measured indirectly utilizing heterodyning ( frequency conversion ). A reference signal of

1540-414: The same speed (the speed of light), giving them wavelengths inversely proportional to their frequencies. c = f λ , {\displaystyle \displaystyle c=f\lambda ,} where c is the speed of light ( c in vacuum or less in other media), f is the frequency and λ is the wavelength. In dispersive media , such as glass, the speed depends somewhat on frequency, so

1584-418: The same term [REDACTED] This disambiguation page lists articles associated with the title Kepler star . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Kepler_star&oldid=708052490 " Category : Disambiguation pages Hidden categories: Short description

1628-546: The star being transited, such as in a binary system . In cases such as these, there is more surface area producing light than is assumed, so a given transit signal is larger than assumed. Since roughly 34% of stellar systems are binaries, up to 34% of KOI signals could be from planets within binary systems and, consequently, be larger than estimated (assuming planets are as likely to form in binary systems as they are in single star systems). However, additional observations can rule out these possibilities and are essential to confirming

1672-506: The stars, making it only the 4th known stellar system to exhibit such behavior. KOI-126 is a triple star system comprising two low mass (0.24 and 0.21 solar masses ( M ☉ )) stars orbiting each other with a period of 1.8 days and a semi-major axis of 0.02 AU. Together, they orbit a 1.3  M ☉ star with a period of 34 days and a semi-major axis of 0.25 AU. All three stars eclipse one another which allows for precise measurements of their masses and radii. This makes

1716-461: The strobing frequency will also appear stationary. Higher frequencies are usually measured with a frequency counter . This is an electronic instrument which measures the frequency of an applied repetitive electronic signal and displays the result in hertz on a digital display . It uses digital logic to count the number of cycles during a time interval established by a precision quartz time base. Cyclic processes that are not electrical, such as

1760-473: The wave speed is independent of frequency), frequency has an inverse relationship to the wavelength , λ ( lambda ). Even in dispersive media, the frequency f of a sinusoidal wave is equal to the phase velocity v of the wave divided by the wavelength λ of the wave: f = v λ . {\displaystyle f={\frac {v}{\lambda }}.} In the special case of electromagnetic waves in vacuum , then v = c , where c

1804-419: The wavelength is not quite inversely proportional to frequency. Sound propagates as mechanical vibration waves of pressure and displacement, in air or other substances. In general, frequency components of a sound determine its "color", its timbre . When speaking about the frequency (in singular) of a sound, it means the property that most determines its pitch . The frequencies an ear can hear are limited to

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1848-455: The wavelength of the sound waves (distance between repetitions) is approximately inversely proportional to frequency. In Europe , Africa , Australia , southern South America , most of Asia , and Russia , the frequency of the alternating current in household electrical outlets is 50 Hz (close to the tone G), whereas in North America and northern South America, the frequency of

1892-451: Was confirmed in 2019. From the Kepler data released to the public, one system has been confirmed to have a planet, Kepler-40 . Kepler-20 (KOI-70) has transit signals indicating the existence of at least four planets. KOI-70.04 is one of the smallest extrasolar planets discovered around a main-sequence star (at 0.6 Earth radii) to date, and the second smallest known extrasolar planet after Draugr . The likelihood of KOI 70.04 being of

1936-403: Was discovered. For all 150,000 stars that were watched for transits by Kepler, there are estimates of each star's surface temperature , radius , surface gravity and mass . These quantities are derived from photometric observations taken prior to Kepler's launch at the 1.2 m reflector at Fred Lawrence Whipple Observatory . For KOIs, there is, additionally, data on each transit signal:

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