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HD 189733

Coordinates:Sky map20h00m43.7133s,+22° 42′ 39.07″
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HD 189733 AB

The location of the HD 189733 system.
Observation data
EpochJ2000.0EquinoxJ2000.0
Constellation Vulpecula
HD 189733 A
Right ascension 20h00m43.71294s[1]
Declination +22° 42′ 39.0732″[1]
Apparent magnitude(V) 7.676[2]
HD 189733 B
Right ascension 20h00m42.97791s[3]
Declination +22° 42′ 34.1785″[3]
Apparent magnitude(V) ~10
Characteristics
Spectral type K1.5V[2]/M[4]
Apparent magnitude(B) 8.609 ±0.016/[2]
Apparent magnitude(J) 6.07[2]/10.116 ±0.041[5]
Apparent magnitude(H) 5.59[2]/9.545 ±0.086[5]
Apparent magnitude(K) 5.54[2]/9.323 ±0.027[5]
Variable type BY Draconis[2][6]
Astrometry
HD 189733 A
Radial velocity(Rv)−2.53±0.12[1]km/s
Proper motion(μ)RA:−3.208(11)mas/yr[1]
Dec.:−250.323(14)mas/yr[1]
Parallax(π)50.5668 ± 0.0162mas[1]
Distance64.50 ± 0.02ly
(19.776 ± 0.006pc)
Absolute magnitude(MV)6.2[7]
HD 189733 B
Radial velocity(Rv)1.46±1.21[3]km/s
Proper motion(μ)RA:−12.193(9)mas/yr[3]
Dec.:−253.993(12)mas/yr[3]
Parallax(π)50.6291 ± 0.0136mas[3]
Distance64.42 ± 0.02ly
(19.751 ± 0.005pc)
Orbit
CompanionHD 189733 B
Period(P)3,200yr
Semi-major axis(a)11.38[8]"
(216AU)
Details
Mass0.846+0.068
−0.049[9]M☉
Radius0.805±0.016[10]R☉
Luminosity0.328±0.011[10]L☉
Surface gravity(logg)4.56±0.03[10]cgs
Temperature4875±43[10]K
Metallicity[Fe/H]−0.03±0.08[11]dex
Rotation11.953±0.009days[12]
Age4.3±2.8[10]Gyr
Other designations
V452 Vulpeculae,BD+22 3887,GJ4130,HD189733,HIP98505,SAO88060,LTT15851,NLTT48568,Wolf864,TOI-4470,TIC256364928,TYC2141-972-1,2MASSJ20004370+2242391[2]
Database references
SIMBADA
B
Exoplanet Archivedata

HD 189733,also catalogued asV452 Vulpeculae,is abinary starsystem 64.5light-years(19.8parsecs) away in theconstellationofVulpecula(theFox). The primary star is suspected to be anorange dwarfstar,[2]while the secondary star is ared dwarfstar.[5]Given that this system has the same visual magnitude asHD 209458,it promises much for the study of close transiting extrasolar planets. The star can be found with binoculars 0.3 degrees east of theDumbbell Nebula(M27).

As of 2005, it has been confirmed that anexoplanet,HD 189733 b,orbits the primary star within the system.[13]

Stellar system

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Alight curvefor V452 Vulpeculae, plotted fromTESSdata. Both the slow variation of the star's luminosity and the abrupt dips caused by planet transits (which occur every 2.219 days) are visible.

HD 189733 Ais anorange dwarfstarof thespectral typeK1.5V. The star has amassof 81 percent that of theSun,aradiusof 76 percent, and aluminosityof 33 percent. The star is between 89 and 102 percent as enriched inironas the Sun, making the star more than 600 million years old. Its absolute magnitude is 6.2.[7]

The star hasstarspotswhich affect its luminosity by 1.5 percent in visible light.[14]As a result, it is listed in theGeneral Catalogue of Variable Starsas aBY Draconis variablewith the variable star designationV452 Vul.[6]

Discovered in 2006 by theinfrared2MASSastronomical survey,2MASS J20004297+2242342orHD 189733 Bis a dimred dwarfstar ofspectral typeM. The companion was observed at a separation of 216astronomical unitsaway from the primary star.Orbitingin a clockwise orbit (which is nearly perpendicular to the orbital plane of transiting planetHD 189733 b), the orbital period is estimated to be around 3,200 years long.[4]

Planetary system

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HD 189733 Ahas one known planet, designatedHD 189733 b,a gaseous giant 13% larger than Jupiter close enough to complete an orbit every two days. Using spectrometry it was found in 2007 that this planet contains significant amounts ofwater vapour.This planet is the second extrasolar planet where definitive evidence for water has been found.[15]

The chemical signature of water vapour was detected in the atmosphere of this planet. Although HD 189733b with atmospheric temperatures rising above 1,000°C(1,830°F) is far from being habitable, this finding increases the likelihood that water, an essential component of life, would be found on a more Earth-like planet in the future.[16]

Astronomers have created a rough map of HD 189733b's cloud-top features using data from the Spitzer infrared space telescope.

Although Spitzer could not resolve the planet into a disk, by measuring changes as the planet rotated, the team created a simple longitudinal map. That is, they measured the planet's brightness in a series of pole-to-pole strips across the planet's visible cloud-tops, then assembled those strips into an overall picture.

Probably due to strong winds, the hottest point on the planet seems to be "offset by about 30 degrees longitudinally" from the substellar point ( "high noon" ).[17]

In late 2008, the spectral signature of carbon dioxide was found in HD 189733b's atmosphere.[18]

In 2013,albedomeasurements at visible wavelengths in the range of 290–570 nm using the Hubble Space Telescope STIS (Space Telescope Imaging Spectrograph) instrument, reported in the Astrophysical Journal Letters, determine the planet to have a deep blue hue due to optically thick reflective clouds containing silicates (glass) "rain".[19][20]The paper detailing the results reports measurement of "geometric albedos of Ag = 0.40 ± 0.12 at 290–450 nm [near ultraviolet to blue in the visible light region of the electromagnetic spectrum] and Ag < 0.12 at 450–570 nm... with sodium absorption suppressing the scattered light signal beyond ~450 nm as predicted by models of hot Jupiter atmospheres."[20]

An atmospheric transmission spectrum taken in 2020 has shown the presence of opaque haze, and spectral signatures of sodium and potassium.[21]

Transit timing variations ofHD 189733 bwere discovered in 2021, suggesting other planets do exist in the system.[22]

The HD 189733 planetary system[23]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b 1.123±0.045MJ 0.03100±0.0006 2.218575200(77) <0.0039 85.58±0.06° 1.138±0.027RJ

Star-planet interaction controversy

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In 2008, a team of astronomers first described how as the exoplanet orbiting HD 189733 A reaches a certain place in its orbit, it causes increasedstellar flaring.In 2010, a different team found that every time they observe the exoplanet at a certain position in its orbit, they also detectedX-rayflares. Theoretical research since 2000 suggested that an exoplanet very near to the star that it orbits may cause increased flaring due to the interaction of theirmagnetic fields,or because oftidal forces.In 2019, astronomers analyzed data fromArecibo Observatory,MOST,and the Automated Photoelectric Telescope, in addition to historical observations of the star at radio, optical, ultraviolet, and X-ray wavelengths to examine these claims. They found that the previous claims were exaggerated and the host star failed to display many of the brightness and spectral characteristics associated with stellar flaring and solaractive regions,including sunspots. Their statistical analysis also found that many stellar flares are seen regardless of the position of the exoplanet, therefore debunking the earlier claims. The magnetic fields of the host star and exoplanet do not interact, and this system is no longer believed to have a "star-planet interaction."[24]Some researchers had also suggested that HD 189733 accretes, or pulls, material from its orbiting exoplanet at a rate similar to those found around youngprotostarsinT Tauri Star systems.Later analysis demonstrated that very little, if any, gas was accreted from the "hot Jupiter" companion.[25]

See also

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References

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  1. ^abcdeVallenari, A.; et al. (Gaia collaboration) (2023)."GaiaData Release 3. Summary of the content and survey properties ".Astronomy and Astrophysics.674:A1.arXiv:2208.00211.Bibcode:2023A&A...674A...1G.doi:10.1051/0004-6361/202243940.S2CID244398875. Gaia DR3 record for this sourceatVizieR.
  2. ^abcdefghi"HD 189733".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2013-07-11.
  3. ^abcdeVallenari, A.; et al. (Gaia collaboration) (2023)."GaiaData Release 3. Summary of the content and survey properties ".Astronomy and Astrophysics.674:A1.arXiv:2208.00211.Bibcode:2023A&A...674A...1G.doi:10.1051/0004-6361/202243940.S2CID244398875. Gaia DR3 record for this sourceatVizieR.
  4. ^abBakos, Gáspár Á.; et al. (2006)."A Stellar Companion in the HD 189733 System with a Known Transiting Extrasolar Planet".The Astrophysical Journal Letters.641(1): L57–L60.arXiv:astro-ph/0602136.Bibcode:2006ApJ...641L..57B.doi:10.1086/503671.
  5. ^abcd"HD 189733B".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2013-07-11.
  6. ^ab"GCVS query result: V452 Vul".General Catalog of Variable Stars.Sternberg Astronomical Institute,Moscow, Russia.Retrieved2009-05-22.
  7. ^ab"HD 189733 b".www.exoplanetkyoto.org.Retrieved2021-11-25.
  8. ^"20 00 43.71347 +22 42 39.0645".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2013-07-11.
  9. ^de Kok, R. J.; et al. (2013)."Detection of carbon monoxide in the high-resolution day-side spectrum of the exoplanet HD 189733b".Astronomy and Astrophysics.554:A82.arXiv:1304.4014.Bibcode:2013A&A...554A..82D.doi:10.1051/0004-6361/201321381.
  10. ^abcdeBoyajian, T.; et al. (2015)."Stellar diameters and temperatures - VI. High angular resolution measurements of the transiting exoplanet host stars HD 189733 and HD 209458 and implications for models of cool dwarfs".Monthly Notices of the Royal Astronomical Society.447(1): 846–857.arXiv:1411.5638.Bibcode:2015MNRAS.447..846B.doi:10.1093/mnras/stu2502.
  11. ^Torres, Guilermo; et al. (2008)."Improved Parameters for Extrasolar Transiting Planets".Astrophysical Journal.677(2): 1324–1342.arXiv:0801.1841.Bibcode:2008ApJ...677.1324T.doi:10.1086/529429.
  12. ^Henry, Gregory W.; Winn, Joshua N. (2008)."The Rotation Period of the Planet-Hosting Star HD 189733".The Astronomical Journal.135(1): 68–71.arXiv:0709.2142.Bibcode:2008AJ....135...68H.doi:10.1088/0004-6256/135/1/68.
  13. ^Bouchy, F.; et al. (2005)."ELODIE metallicity-biased search for transiting Hot Jupiters II. A very hot Jupiter transiting the bright K star HD 189733".Astronomy and Astrophysics.444(1): L15–L19.arXiv:astro-ph/0510119.Bibcode:2005A&A...444L..15B.doi:10.1051/0004-6361:200500201.
  14. ^Winn, J. N.; et al. (2007). "The Transit Light Curve Project. V. System parameters and stellar rotation period of HD 189733".The Astronomical Journal.133(4): 1828–1835.arXiv:astro-ph/0612224.Bibcode:2007AJ....133.1828W.doi:10.1086/512159.S2CID11265250.
  15. ^"Water vapour found on exoplanet".BBC News.2007-07-11.Retrieved2007-07-12.
  16. ^"'Clear Signs of Water' on Distant Planet ".Space.com.2007-07-11.Retrieved2008-02-02.
  17. ^"CfA Press Release - First Map of an Extrasolar Planet".2007-05-09.Retrieved2008-12-06.
  18. ^Sanderson, Katharine (2008-11-25)."Carbon dioxide discovered on distant planet".Nature News.doi:10.1038/news.2008.1248.Retrieved2008-11-25.
  19. ^"Glass rain may give planet blue hue".BBC News.2013-07-11.Retrieved2013-07-12.
  20. ^ab"The deep blue color of HD 189733b: albedo measurements with HST /STIS at visible wavelengths"(PDF).Retrieved2013-07-12.
  21. ^Oshagh, M.; Bauer, F. F.; Lafarga, M.; Molaverdikhani, K.; Amado, P. J.; Nortmann, L.; Reiners, Ansgar; Guzmán-Mesa, A.; Pallé, E.; Nagel, E.; Caballero, J. A.; Casasayas-Barris, N.; Claret, A.; Czesla, S.; Galadí, D.; Henning, Th.; Khalafinejad, S.; López-Puertas, M.; Montes, D.; Quirrenbach, A.; Ribas, I.; Stangret, M.; Yan, F.; Zapatero-Osorio, María Rosa; Zechmeister, M. (2020), "The widest broadband transmission spectrum (0.38–1.71μm) of HD 189733b from ground-based chromatic Rossiter-McLaughlin observations",Astronomy & Astrophysics,643:A64,arXiv:2009.13823,Bibcode:2020A&A...643A..64O,doi:10.1051/0004-6361/202039213,S2CID221995707
  22. ^Baluev, Roman V. (2022), "The impact of photospheric brightness field on exoplanetary transit timings and the TTV excess of HD 189733 b",Monthly Notices of the Royal Astronomical Society,509:1048–1061,arXiv:2110.07901,doi:10.1093/mnras/stab3073
  23. ^Bonomo, A. S.; Desidera, S.; et al. (June 2017). "The GAPS Programme with HARPS-N at TNG. XIV. Investigating giant planet migration history via improved eccentricity and mass determination for 231 transiting planets".Astronomy & Astrophysics.602:A107.arXiv:1704.00373.Bibcode:2017A&A...602A.107B.doi:10.1051/0004-6361/201629882.S2CID118923163.
  24. ^Route, Matthew (February 10, 2019)."The Rise of ROME. I. A Multiwavelength Analysis of the Star-Planet Interaction in the HD 189733 System".The Astrophysical Journal.872(1): 79.arXiv:1901.02048.Bibcode:2019ApJ...872...79R.doi:10.3847/1538-4357/aafc25.S2CID119350145.
  25. ^Route, Matthew; Looney, Leslie (December 20, 2019)."ROME (Radio Observations of Magnetized Exoplanets). II. HD 189733 Does Not Accrete Significant Material from Its Exoplanet Like a T Tauri Star from a Disk".The Astrophysical Journal.887(2): 229.arXiv:1911.08357.Bibcode:2019ApJ...887..229R.doi:10.3847/1538-4357/ab594e.S2CID208158242.
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