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KIC 8462852[1] (also Tabby's Star or Boyajian's Star) is an F-type main-sequence star located in the constellation Cygnus approximately 1,280 light-years (390 pc) from Earth.[2] Unusual light fluctuations of the star were discovered by citizen scientists as part of the Planet Hunters project, and in September 2015 astronomers and citizen scientists associated with the project posted a preprint of a paper describing the data and possible interpretations.[1] The discovery was made from data collected by the Kepler space telescope,[1][6] which observes changes in the brightness of distant stars to detect exoplanets.[7]

KIC 8462852
KIC 8462852 in IR and UV.png
KIC 8462852 in infrared and ultraviolet
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Cygnus
Right ascension 20h 06m 15.457s
Declination +44° 27′ 24.61″
Apparent magnitude (V) +11.705±0.017
Characteristics
Evolutionary stage Main sequence[1]
Spectral type F3V
B−V color index 0.557
V−R color index 0.349
R−I color index 0.305
J−H color index 0.212
J−K color index 0.264
Astrometry
Proper motion (μ) RA: −9.9±2.6 mas/yr
Dec.: −10.5±2.4 mas/yr
Parallax (π) 2.555 ± 0.311[2] mas
Distance 1276.6+398.2
−245.3
ly
(391.4+122.1
−75.2
pc)
Absolute magnitude (MV) 3.08[1][3]
Details
Mass 1.43[1] M
Radius 1.58[1] R
Luminosity (bolometric) 4.68[1] L
Surface gravity (log g) 4.0±0.2[4] cgs
Temperature 6750±120[1] K
Metallicity 0.0±0.1[1]
Rotation 0.8797±0.0001 days[1]
Rotational velocity (v sin i) 84±4[1] km/s
Other designations
Tabby's Star, Boyajian's Star, WTF Star, TYC 3162-665-1,[1] 2MASS J20061546+4427248,[1] LGM-2[5]
Database references
SIMBAD data
KIC data

Several hypotheses have been proposed to explain the star's large irregular changes in brightness as measured by its light curve, but none to date fully explain all aspects of the curve. The leading hypothesis, based on a lack of observed infrared light, posits a swarm of cold, dusty comet fragments in a highly eccentric orbit.[8][9][10] However, the notion that disturbed comets from such a cloud could exist in high enough numbers to obscure 22% of the star's observed luminosity has been doubted.[11] Another hypothesis is that of a large number of small masses in "tight formation" orbiting the star.[6] However, spectroscopic study of the system has found no evidence for coalescing material or hot close-in dust or circumstellar matter from an evaporating or exploding planet within a few astronomical units of the mature central star.[8][12] It has also been hypothesized that the changes in brightness could be signs of activity associated with intelligent extraterrestrial life constructing a Dyson swarm.[6][11][13][14] However, this hypothesis may be less probable than some other explanations, as it is disfavored given the current insufficiency of evidence for the existence of advanced alien civilizations.[15]

KIC 8462852 is not the only star that has large irregular dimmings, but all other such stars are young stellar objects called YSO dippers, that have different dimming patterns. An example of such an object is EPIC 204278916.[16][17]

A significant new dimming event of KIC 8462852 began in May 2017, which provided the opportunity for worldwide, real-time, coordinated data collection.[18][19]

Contents

NomenclatureEdit

KIC is an acronym for the Kepler Input Catalog, 8462852 being the star's catalog number. Colloquially the names "Tabby's Star" and "Boyajian's Star" refer to the initial study's lead author, Tabetha S. Boyajian;[20][21] KIC 8462852 is sometimes called the "WTF Star", after the study's subtitle "Where's The Flux?"[22][23][24][25] (a joking reference to the colloquial expression of disbelief "WTF").[26]

Apparent locationEdit

 
Map showing location of NGC 6866. KIC 8462852 is northeast between NGC 6866 and ο¹ Cygni.

KIC 8462852 in the constellation Cygnus is located roughly halfway between the major visually apparent (visible to the naked eye) bright stars Deneb (α Cyg, α Cygni, Alpha Cygni) and Delta Cygni (δ Cyg, δ Cygni) as part of the Northern Cross.[27][28] KIC 8462852 is situated south of Omicron¹ Cygni (ο¹ Cygni, 31 Cygni), and northeast of the star cluster NGC 6866.[28] While only a few arcminutes away from the cluster, it is unrelated and closer to the Sun than it is to the star cluster.

With an apparent magnitude of 11.7, the star cannot be seen by the naked eye, but is visible with a 5-inch (130 mm) telescope[29] in a dark sky with little light pollution.

History of observationsEdit

KIC 8462852 was observed as early as the year 1890.[30][31][32] The star was cataloged in the Tycho, 2MASS, UCAC4 and WISE astronomical catalogs[33] (published in 1997, 2003, 2009 and 2012, respectively).[34][35][36][37]

The main source of information about the luminosity fluctuations of KIC 8462852 is the Kepler space observatory. During its primary and extended mission from 2009 to 2013 it continuously monitored the light curves of over 100,000 stars in a patch of sky in the constellations Cygnus and Lyra.[38]

LuminosityEdit

Observations of the luminosity of the star by the Kepler space telescope show small, frequent, non-periodic dips in brightness, along with two large recorded dips in brightness roughly 750 days apart. The amplitude of the changes in the star's brightness, and the aperiodicity of the changes, mean that this star is of particular interest for astronomers.[11] The star's changes in brightness are consistent with many small masses orbiting the star in "tight formation".[6]

The first major dip, on 5 March 2011, reduced the star's brightness by up to 15%, and the other (on 28 February 2013) by up to 22%. In comparison, a planet the size of Jupiter would only obscure a star of this size by 1%, indicating that whatever is blocking light during the star's major dips is not a planet, but rather something covering up to half the width of the star.[11] Due to the failure of two of Kepler's reaction wheels, the star's predicted 750-day dip around February 2015 was not recorded;[1][14] further observations are planned for May 2017.[14] The irregular light dips do not show a pattern.[39]

In addition to the day-long dimmings, a study of a century's worth of photographic plates suggests that the star has gradually faded from 1890 to 1989 by about 20%, which would be unprecedented for any F-type main sequence star.[30][31] However, teasing accurate magnitudes from long-term photographic archives is a complex procedure, requiring adjustment for equipment changes, and is strongly dependent on the choice of comparison stars. Another study, examining the same photographic plates, concluded that the possible century-long dimming was likely a data artifact, and not a real astrophysical event.[32]

A third study, using light measurements by the Kepler observatory over a four-year period, determined that KIC 8462852 dimmed at about 0.34% per year before dimming more rapidly by about 2.5% in 200 days. It then returned to its previous slow fade rate. The same technique was used to study 193 stars in its vicinity and 355 stars similar in size and composition to KIC 8462852. None of these stars exhibited such dimming.[40]

Kepler light curvesEdit

HypothesesEdit

Based on KIC 8462852's spectrum and stellar type, its changes in brightness could not be attributed to intrinsic variability;[1] while a few hypotheses have been proposed involving material orbiting the star and blocking its light, none of these fully fit the observed data.

Some of the proposed explanations involve instrument or data artifacts, interstellar dust, a series of giant planets with very large ring structures,[41][42] a recently captured asteroid field,[1] the system undergoing Late Heavy Bombardment,[8][12] and an artificial megastructure orbiting the star.[43]

Younger star with coalescing material around itEdit

 
Artist's impression of a young star with coalescing material around it

Astronomer Jason Wright and others who have studied KIC 8462852 have suggested that if the star is younger than its position and speed would suggest, then it may still have coalescing material around it.[25][44][22]

A 0.8–4.2 micron spectroscopic study of the system using the NASA Infrared Telescope Facility (NASA IRTF) found no evidence for coalescing material within a few astronomical units of the mature central star.[8][12]

Planetary debris fieldEdit

 
Artist's impression of a massive collision with a proto-planet

High-resolution spectroscopy and imaging observations have also been made, as well as spectral energy distribution analyses using the Nordic Optical Telescope in Spain.[1][41] A massive collision scenario would create warm dust that glows in infrared wavelengths, but there is no observed excess infrared energy, ruling out massive planetary collision debris.[11] Other researchers think the planetary debris field explanation is unlikely, given the very low probability that Kepler would ever witness such an event due to the rarity of collisions of such size.[1]

As with the possibility of coalescing material around the star, spectroscopic studies using the NASA IRTF found no evidence for hot close-in dust or circumstellar matter from an evaporating or exploding planet within a few astronomical units of the central star.[8][12] Similarly, a study of past infrared data from NASA's Spitzer Space Telescope and Wide-field Infrared Survey Explorer found no evidence for an excess of infrared emission from the star, which would have been an indicator of warm dust grains that could have come from catastrophic collisions of meteors or planets in the system. This absence of emission supports the hypothesis that a swarm of cold comets on an unusually eccentric orbit could be responsible for the star's unique light curve, but more studies are needed.[8][4]

A cloud of disintegrating cometsEdit

 
Artist's impression of an orbiting swarm of dusty comet fragments

One proposed explanation for the reduction in light is that it is due to a cloud of disintegrating comets orbiting the star elliptically.[1][8][10][45] This scenario would assume that KIC 8462852's planetary system has something similar to the Oort cloud and that gravity from a nearby star caused comets from said cloud to fall closer into system, thereby obstructing KIC 8462852's spectra. Evidence supporting this hypothesis includes an M-type red dwarf within 132 billion kilometers (885 AU) of KIC 8462852.[1] However, the notion that disturbed comets from such a cloud could exist in high enough numbers to obscure 22% of the star's observed luminosity has been doubted.[11]

Submillimetre wavelength observations searching for farther-out cold dust in an asteroid belt akin to the Sun's Kuiper Belt suggest that a distant "catastrophic" planetary disruption explanation is unlikely; the possibility of a disrupted asteroid belt scattering comets into the inner system is still to be determined.[46]

An artificial megastructureEdit

 
Artist's impression of a Dyson swarm

Astronomers have hypothesized that the objects eclipsing KIC 8462852 could be parts of a megastructure made by an alien civilization, such as a Dyson swarm,[6][22][43][45][47][48] a hypothetical structure that an advanced civilization might build around a star to intercept some of its light for their energy needs.[49][50][51] Due to extensive media coverage on this matter, KIC 8462852 has been compared by Kepler's Steve Howell to KIC 4150611,[52] another star with an odd light curve (which proved, after years of research, to be a part of a five-star system).[53] The likelihood of extraterrestrial intelligence being the cause of the dimming is very low; however, the star remains an outstanding SETI target because natural explanations have yet to fully explain the dimming phenomenon.[22][43]

According to Steinn Sigurðsson, the idea that the dimming is caused by an artificial megastructure is a falsifiable hypothesis and is thus scientifically valid.[15] However, it remains less probable than some other explanations, as it is disfavored by Occam's razor given the current insufficiency of evidence for the existence of extraterrestrial civilizations.[15]

Consumption of a planetEdit

In December 2016 a team of researchers proposed that KIC 8462852 swallowed a planet causing a temporary and unobserved increase in brightness due to the release of gravitational energy. Planetary debris still in orbit of the star would then explain its observed drops in intensity.[54]

Nonequilibrium chaotic variations due to near-criticalityEdit

Sheikh et al. (2016) note that KIC 8462852's observed brightness variations appear to fit the "avalanche statistics" known to occur in a system close to a phase-transition.[15][55]

"Avalanche statistics" with a self-similar or power-law spectrum are a universal property of complex dynamical systems operating close to a phase transition or bifurcation point between two different types of dynamical behavior. Such close-to-critical systems are often observed to exhibit behavior that is intermediate between "order" and "chaos". Three other stars in the Kepler Input Catalog likewise exhibit similar "avalanche statistics" in their brightness variations, and that all three are known to be magnetically active. It has been conjectured that stellar magnetism may be involved in KIC 8462852.[55]

Large ringed planet followed by Trojan swarmsEdit

Ballesteros et al (2017) proposed a large, ringed planet trailed by a swarm of Trojan asteroids in its L5 Lagrangian point, and estimated an orbit that predicts another event in early 2021 due to the leading Trojans followed by another transit of the hypothetical planet in 2023.[56] The model suggests a planet with a radius of 4.7 Jupiter radii, large for a planet (unless very young). An early Red dwarf of about 0.5 R would be easily seen in infrared.[57] The current radial velocity observations available (four runs at σv ≈ 400m s−1) hardly constrain the model, but new radial velocity measurements would greatly reduce the uncertainty. The model predicts a discrete and short-lived event for the May 2017 dimming episode, corresponding to the secondary eclipse of the planet passing behind KIC 8246852, with about a 3 per cent decrease in the stellar flux with a transit time of about 2 days. If this is the cause of the May 2017 event, the planet's orbital period is more precisely estimated as 12.41 years and semi-major-axis of 5.9 AU.[56][58]

Follow-up studiesEdit

In the aggregate numerous optical telescopes continually monitor KIC 8462852 in anticipation of another multi-day dimming event, with planned follow-up observations of a dimming event using large telescopes equipped with spectrographs to determine if the eclipsing mass is a solid object, or composed of dust or gas.[59] Additional follow-up observations may involve the ground-based Green Bank Telescope, the Very Large Array Radio Telescope,[41][60] and future orbital telescopes dedicated to exoplanetology such as WFIRST, TESS, and PLATO.[43][51]

A Kickstarter fund-raising campaign was led by Tabetha Boyajian, the lead author of the initial study on KIC 8462852's anomalous light curve. The project proposes to use the Las Cumbres Observatory Global Telescope Network for continuous monitoring of the star. The campaign raised over US$100,000, enough for one year of telescope time.[61] Furthermore, more than fifty amateur astronomers working under the aegis of the American Association of Variable Star Observers have been providing effectively full coverage since AAVSO's alert about the star in October 2015, [62]namely a nearly continuous photometric record.[63]

SETI resultsEdit

In October 2015, the SETI Institute used the Allen Telescope Array to look for radio emissions from possible intelligent extraterrestrial life in the vicinity of the star.[64][65] After an initial two-week survey, the SETI Institute reported that it found no evidence of technology-related radio signals from the star system.[66][67][68] No narrowband radio signals were found at a level of 180–300 Jy in a 1 Hz channel, or medium-band signals above 10 Jy in a 100 kHz channel.[67]

The VERITAS gamma-ray observatory was used to search for ultra-fast optical transients from astronomical objects, with astronomers developing an efficient method sensitive to nanosecond pulses with fluxes as low as about one photon per square meter. This technique was applied on archival observations of KIC 8462852 from 2009 to 2015, but no emissions were detected.[69][70]

EPIC 204278916Edit

A star called EPIC 204278916, as well as some other young stellar objects, have been observed to exhibit dips similar to those observed in KIC 8462852. They differ in several aspects, however. EPIC 204278916 shows much deeper dips than KIC 8462852, and they are grouped over a shorter period, whereas the dips at KIC 8462852 are spread out over several years. Furthermore, EPIC 204278916 is surrounded by a proto-stellar disc, whereas KIC 8462852 appears to be a normal F-type star displaying no evidence of a disc.[16]

May 2017 dimming eventEdit

On 20 May 2017, Boyajian and her colleagues reported, via The Astronomer's Telegram, on an ongoing dimming event which possibly began on 14 May 2017;[18] it was detected by the Las Cumbres Observatory Global Telescope Network, specifically by its telescope located in Maui (LCO Maui); this was verified by the Fairborn Observatory (part of the N2K Consortium) in Southern Arizona (and later by LCO Canary Islands).[19][71][72] Further optical and infrared spectroscopy and photometry were urgently requested, given the short duration, measured in days or weeks, of these events.[18] Observations from multiple observers globally were coordinated, including polarimetry.[73] Furthermore, the independent SETI projects Breakthrough Listen and Near-InfraRed Optical SETI (NIROSETI), both at Lick Observatory, continue to monitor the star.[18][74][75][76] By the end of the three-day dimming event,[77] a dozen observatories had taken spectra, with some astronomers having dropped their own projects to provide telescope time and resources. More generally the astronomical community was described as having gone "mildly bananas" over the opportunity to collect data in real-time on the unique star,[78] Boyajian and Wright having both taken to Twitter.[79][80]

Initial spectra with FRODOSpec at the 2.0 meter Liverpool Telescope showed no evidence of any changes visible between a reference spectrum and this dip.[74][75][76][81][82] Several observatories, including the twin Keck telescopes (HIRES)[83] and numerous citizen science observatories, are taking spectra of the star.[18][75][76] This dimming dip has a complex shape, is ongoing,[84] and initially had a pattern similar to the one at 759.75 days from the kepler event 2, epoch 2 data.[85]

See alsoEdit

ReferencesEdit

  1. ^ a b c d e f g h i j k l m n o p q r s t u Boyajian, T. S.; LaCourse, D. M.; Rappaport, S. A.; Fabrycky, D.; Fischer, D. A.; et al. (April 2016). "Planet Hunters IX. KIC 8462852 – where's the flux?". Monthly Notices of the Royal Astronomical Society. 457 (4): 3988–4004. arXiv:1509.03622 . Bibcode:2016MNRAS.457.3988B. doi:10.1093/mnras/stw218. 
  2. ^ a b Hippke, Michael; Angerhausen, Daniel (18 September 2016). "A first view with GAIA on KIC 8462852 – Distance estimates and a comparison to other F stars". arXiv:1609.05492  [astro-ph]. 
  3. ^ Pecaut, Mark J.; Mamajek, Eric E. (September 2013). "Intrinsic Colors, Temperatures, and Bolometric Corrections of Pre-main-sequence Stars". The Astrophysical Journal Supplement. 208 (1). 9. arXiv:1307.2657 . Bibcode:2013ApJS..208....9P. doi:10.1088/0067-0049/208/1/9. 
  4. ^ a b Marengo, Massimo; Hulsebus, Alan; Willis, Sarah (November 2015). "KIC 8462852: The Infrared Flux". The Astrophysical Journal Letters. 814 (1). L15. arXiv:1511.07908 . Bibcode:2015ApJ...814L..15M. doi:10.1088/2041-8205/814/1/L15. 
  5. ^ Freeman, David (25 August 2016). "Are Space Aliens Behind The 'Most Mysterious Star In The Universe?'". The Huffington Post. Retrieved 11 December 2016. 
  6. ^ a b c d e Andersen, Ross (13 October 2015). "The Most Mysterious Star in Our Galaxy". The Atlantic. Retrieved 13 October 2015. 
  7. ^ Grush, Loren (16 October 2015). "Why it's so hard for astronomers to discuss the possibility of alien life". The Verge. Retrieved 17 October 2015. 
  8. ^ a b c d e f g Clavin, Whitney; Johnson, Michele (24 November 2015). "Strange Star Likely Swarmed by Comets". NASA. Retrieved 24 November 2015. 
  9. ^ Griffin, Andrew (25 November 2015). "Star that could have 'alien megastructure' around it is almost certainly covered by a swarm of comets, Nasa says". The Independent. Retrieved 26 November 2015. 
  10. ^ a b Bodman, Eva H. L.; Quillen, Alice (27 November 2015). "KIC 8462852: Transit of a Large Comet Family". arXiv:1511.08821  [astro-ph.EP]. 
  11. ^ a b c d e f Plait, Phil (14 October 2015). "Did Astronomers Find Evidence of an Alien Civilization? (Probably Not. But Still Cool.)". Slate. Retrieved 15 October 2015. 
  12. ^ a b c d Lisse, Carey; Sitko, Michael; Marengo, Massimo (December 2015). "IRTF/SPeX Observations of the Unusual Kepler Light Curve System KIC8462852". The Astrophysical Journal Letters. 815 (2). L27. arXiv:1512.00121 . Bibcode:2015ApJ...815L..27L. doi:10.1088/2041-8205/815/2/L27. 
  13. ^ Kaplan, Sarah (15 October 2015). "The strange star that has serious scientists talking about an alien megastructure". The Washington Post. Retrieved 15 October 2015. 
  14. ^ a b c Aron, Jacob (18 September 2015). "Citizen scientists catch cloud of comets orbiting distant star". New Scientist. Retrieved 15 October 2015. 
  15. ^ a b c d Sigurðsson, Steinn (19 December 2016). "New Clues as to Why Boyajian's Star is Dimming". Physics. American Physical Society. 9. 150. Bibcode:2016PhyOJ...9..150S. doi:10.1103/Physics.9.150. 
  16. ^ a b Scaringi, S.; Manara, C. F.; Barenfeld, S. A.; Groot, P. J.; Isella, A.; et al. (December 2016). "The peculiar dipping events in the disk-bearing young-stellar object EPIC 204278916". Monthly Notices of the Royal Astronomical Society. 463 (2): 2265–2272. arXiv:1608.07291 . Bibcode:2016MNRAS.463.2265S. doi:10.1093/mnras/stw2155. 
  17. ^ Nowakowski, Tomasz (30 August 2016). "Irregular dimming of a young stellar object investigated by astronomers". Phys.org. Retrieved 5 September 2016. 
  18. ^ a b c d e Boyajian, Tabetha; et al. (20 May 2017). "A Drop in Optical Flux from Boyajian's Star". The Astronomer's Telegram. Retrieved 21 May 2017. 
  19. ^ a b Koren, Marina (19 May 2017). "The 'Alien Megastructure' Star Is Dimming Again". The Atlantic. Retrieved 23 May 2017. 
  20. ^ Wenz, John (9 February 2016). "NASA's Next Great Telescope Will Settle This Alien Megastructure Mystery For Good". Popular Mechanics. Retrieved 13 February 2016. 
  21. ^ Wright, Jason T. (30 August 2016). "What Could Be Going on with Boyajian's Star? Part I". Retrieved 12 September 2016. 
  22. ^ a b c d Wright, Jason (15 October 2015). "KIC 8462852: Where's the Flux?". AstroWright. Pennsylvania State University. Retrieved 16 October 2015. 
  23. ^ Newsome, John (16 October 2015). "Space anomaly gets extraterrestrial intelligence experts' attention". CNN News. Retrieved 16 October 2015. 
  24. ^ "Discovery of a strange star could mean alien life". Fox News. 15 October 2015. Retrieved 16 October 2015. 
  25. ^ a b King, Bob (16 October 2015). "What's Orbiting KIC 8462852 – Shattered Comet or Alien Megastructure?". Universe Today. Retrieved 16 October 2015. 
  26. ^ Strom, Marcus (15 October 2015). "It's either aliens or a swarm of comets: scientists baffled by WTF 001, our galaxy's strangest star". The Sydney Morning Herald. Retrieved 16 October 2015. 
  27. ^ "KIC10 Search Results". Space Telescope Science Institute. Retrieved 16 October 2015. 
  28. ^ a b Sinnott, Roger W. (2010). Sky & Telescope's Pocket Sky Atlas (3rd ed.). Cambridge, Massachusetts: Sky Publishing. ISBN 978-1-931559-31-7. 
  29. ^ Masi, Gianluca (16 October 2015). "KIC 8462852: A star and its secrets". The Virtual Telescope Project 2.0. Retrieved 22 October 2015. 
  30. ^ a b Aron, Jacob (15 January 2016). "Comets can't explain weird 'alien megastructure' star after all". New Scientist. Retrieved 16 January 2016. 
  31. ^ a b Schaefer, Bradley E. (13 January 2016). "KIC 8462852 Faded at an Average Rate of 0.165+-0.013 Magnitudes Per Century From 1890 To 1989". arXiv:1601.03256  [astro-ph.SR]. 
  32. ^ a b Hippke, Michael; Angerhausen, Daniel (8 February 2016). "KIC 8462852 did likely not fade during the last 100 years". arXiv:1601.07314v2  [astro-ph.EP]. 
  33. ^ "TYC 3162-665-1". SIMBAD. Retrieved 17 June 2016. 
  34. ^ "Hipparcos". European Space Agency. Retrieved 17 June 2016. 
  35. ^ "About 2MASS". California Institute of Technology. Retrieved 17 June 2016. 
  36. ^ "USNO CCD Astrograph Catalog (UCAC)". United States Naval Observatory. Retrieved 17 June 2016. 
  37. ^ Clavin, Whitney; Harrington, J. D. (14 March 2012). "NASA Releases New WISE Mission Catalog of Entire Infrared Sky". NASA. Retrieved 17 June 2016. 
  38. ^ "Kepler: FAQ". NASA. Retrieved 17 June 2016. 
  39. ^ Michael, George (January 2016). "The Great ET Paradox: Why We are Likely to Find Them Before They Find Us". Skeptic. 21 (1): 16–18. 
  40. ^ Montet, Benjamin T.; Simon, Joshua D. (3 August 2016). "KIC 8462852 Faded Throughout the Kepler Mission". arXiv:1608.01316  [astro-ph]. 
  41. ^ a b c Rzetelny, Xaq (16 October 2015). "Something—we're not sure what—is radically dimming a star's light". Ars Technica. Retrieved 17 October 2015. 
  42. ^ Siegel, Ethan (16 October 2015). "No, Astronomers Probably Haven't Found 'Alien Megastructures'". Forbes. Retrieved 17 October 2015. 
  43. ^ a b c d Wright, Jason T.; Cartier, Kimberly M. S.; Zhao, Ming; Jontof-Hutter, Daniel; Ford, Eric B. (January 2016). "The Ĝ Search for Extraterrestrial Civilizations with Large Energy Supplies. IV. The Signatures and Information Content of Transiting Megastructures". The Astrophysical Journal. 816 (1). 17. arXiv:1510.04606 . Bibcode:2016ApJ...816...17W. doi:10.3847/0004-637X/816/1/17. 
  44. ^ Laker, Chris (16 October 2015). "'Alien megastructure' may explain light patterns from 'bizarre' star, say scientists". BT.com. Retrieved 17 October 2015. 
  45. ^ a b Fecht, Sarah (13 October 2015). "Have We Detected Megastructures Built By Aliens Around A Distant Star? Or Just A Cloud Of Comets? Scientists Want To Investigate Further". Popular Science. Retrieved 14 October 2015. 
  46. ^ Thompson, M. A.; Scicluna, P.; Kemper, F.; Geach, J. E.; Dunham, M. M.; et al. (May 2016). "Constraints on the circumstellar dust around KIC 8462852". Monthly Notices of the Royal Astronomical Society: Letters. 458 (1): L39–L43. arXiv:1512.03693 . Bibcode:2016MNRAS.458L..39T. doi:10.1093/mnrasl/slw008. 
  47. ^ "Good night, sleep tight: Advanced alien civilisations rare or absent in the local Universe" (Press release). ASTRON. 15 September 2015. Retrieved 15 October 2015. 
  48. ^ Williams, Lee (15 October 2015). "Astronomers may have found giant alien 'megastructures' orbiting star near the Milky Way". The Independent. Retrieved 15 October 2015. 
  49. ^ Jones, Morris (November–December 2015). "Reconsidering macro-artefacts in SETI searches". Acta Astronautica. 116: 161–165. doi:10.1016/j.actaastro.2015.07.011. 
  50. ^ O'Neill, Ian (14 October 2015). "Has Kepler Discovered an Alien Megastructure?". Discovery.com. Retrieved 17 October 2015. 
  51. ^ a b Siemion, Andrew (29 September 2015). "Prepared Statement by Andrew Siemion – Hearing on Astrobiology". House Committee on Science, Space, and Technology. SpaceRef.com. Retrieved 19 October 2015. 
  52. ^ Kramer, Miriam (18 October 2015). "Scientists have not actually found an alien megastructure orbiting a distant star". Mashable. Retrieved 27 October 2016. 
  53. ^ Gregg, Trevor A.; Prsa, A.; Welsh, W. F.; Orosz, J. A.; Fetherolf, T. (January 2013). A Syzygy of KIC 4150611. 221st Meeting of the American Astronomical Society. 6–10 January 2013. Long Beach, California. 142.12. Bibcode:2013AAS...22114212G. 
  54. ^ Metzger, Brian D.; Shen, Ken J.; Stone, Nicholas C. (21 December 2016). "Secular Dimming of KIC 8462852 Following its Consumption of a Planet". arXiv:1612.07332  [astro-ph.SR]. 
  55. ^ a b Sheikh, Mohammed A.; Weaver, Richard L.; Dahmen, Karin A. (19 December 2016). "Avalanche Statistics Identify Intrinsic Stellar Processes near Criticality in KIC 8462852". Physical Review Letters. American Physical Society. 117 (26). 261101. Bibcode:2016PhRvL.117z1101S. doi:10.1103/PhysRevLett.117.261101. 
  56. ^ a b Ballesteros, Fernando J.; Arnalte-Mur, Pablo; Fernandez-Soto, Alberto; Martinez, Vicent J. (23 May 2017). "KIC 8462852: Will the Trojans return in 2021?". arXiv:1705.08427  [astro-ph.EP]. 
  57. ^ https://twitter.com/david_kipping/status/867186578879385600
  58. ^ https://pbs.twimg.com/media/DAjVXoeW0AEYZJn.jpg:large ORBITAL DIAGRAM HYPOTHESIS OF KIC 8462852
  59. ^ Wall, Mike (28 October 2015). "'Alien Megastructure' Mystery May Soon Be Solved". Space.com. Retrieved 28 October 2015. 
  60. ^ Mack, Eric (17 October 2015). "The story behind 'alien megastructures' scientists may have found (but probably didn't)". CNET. Retrieved 19 October 2015. 
  61. ^ Fecht, Sarah (16 June 2016). "'Alien Megastructure' Star Kickstarter Just Met Its Goal". Popular Science. Retrieved 16 June 2016. 
  62. ^ JARREAU, PAIGE (2017-01-17). "Tabby's Star: The Most Mysterious Star in the Universe Needs You". The Pursuit. Physics and Astronomy. 
  63. ^ "Subreddit FAQ". Subreddit. 
  64. ^ Wall, Mike (19 October 2015). "Search For Intelligent Aliens Near Bizarre Dimming Star Has Begun". Space.com. Retrieved 20 October 2015. 
  65. ^ Orwig, Jessica (23 October 2015). "Scientists are days from finding out if that mysterious star could actually harbor aliens". Business Insider. 
  66. ^ "Looking for Deliberate Radio Signals from KIC 8462852" (Press release). The SETI Institute. 5 November 2015. Retrieved 8 November 2015. 
  67. ^ a b Harp, G. R.; Richards, Jon; Shostak, Seth; Tarter, J. C.; Vakoch, Douglas A.; et al. (July 2016). "Radio SETI Observations of the Anomalous Star KIC 8462852". The Astrophysical Journal. 825 (2). 155. arXiv:1511.01606 . Bibcode:2016ApJ...825..155H. doi:10.3847/0004-637X/825/2/155. 
  68. ^ Schuetz, Marlin; Vakoch, Douglas A.; Shostak, Seth; Richards, Jon (July 2016). "Optical SETI Observations of the Anomalous Star KIC 8462852". The Astrophysical Journal Letters. 825 (1). L5. arXiv:1512.02388 . Bibcode:2016ApJ...825L...5S. doi:10.3847/2041-8205/825/1/L5. 
  69. ^ Abeysekara, A. U.; Archambault, S.; Archer, A.; Benbow, W.; Bird, R.; et al. (February 2016). "A Search for Brief Optical Flashes Associated with the SETI Target KIC 8462852". The Astrophysical Journal Letters. 818 (2). L33. arXiv:1602.00987 . Bibcode:2016ApJ...818L..33A. doi:10.3847/2041-8205/818/2/L33. 
  70. ^ Holder, Jamie; et al. (9 September 2016). "Latest Results from VERITAS: Gamma 2016". arXiv:1609.02881  [astro-ph.HE]. 
  71. ^ Arboleda, Lawrence (20 May 2017). "That 'Alien Megastructure' Star Has Gone Haywire Again And Scientists Are Baffled". The Inquistr. 
  72. ^ Clery, Daniel (22 May 2017). "Star that spurred alien megastructure theories dims again". Science (magazine). Retrieved 25 May 2017. 
  73. ^ Ellis, Tyler (19 May 2017). "WTF Has Gone Into a Dip!". 
  74. ^ a b Steele, Iain; et al. (20 May 2017). "Medium Resolution Spectroscopy of Boyajian's Star (KIC 8462852)". The Astronomer's Telegram. Retrieved 21 May 2017. 
  75. ^ a b c Wright, Jason (19 May 2017). "Tabby's Star is dimming right now (archived video of chat with Jason Wright)". YouTube. Retrieved 21 May 2017. 
  76. ^ a b c Staff (20 May 2017). "Mysterious Tabby's Star dims again: observations needed". The Lined Wolf. Retrieved 21 May 2017. 
  77. ^ Cooper, Keith (24 May 2017). "The Galaxy's strangest star dims again". Astronomy Now. Retrieved 25 May 2017. 
  78. ^ Kaplan, Sarah (24 May 2017). "The weirdest star in the sky is acting up again". The Washington Post. Speaking of Science. 
  79. ^ Wright, Jason (19 May 2017). "ALERT: @tsboyajian's star is dipping". Twitter. 
  80. ^ Boyajian, Tabetha (19 May 2017). "#TabbysStar IS DIPPING! OBSERVE!!". Twitter. 
  81. ^ https://www.dropbox.com/s/isev1ymggilx4hl/KIC-Ca.png?dl=0
  82. ^ https://www.dropbox.com/s/u11lv7d5opeo0rr/KIC-halpha.png?dl=0
  83. ^ https://twitter.com/astronomeara/status/866310803825152001
  84. ^ https://twitter.com/tsboyajian/status/866343024607055872
  85. ^ https://twitter.com/david_kipping/status/866318056947150848

External linksEdit