HD 100546

HD 100546, also known as KR Muscae, is a star 320 light-years from Earth.[4] It is orbited by an approximately 20 MJ exoplanet at 6.5 AU,[6] although further examination of the disk profile indicate it might be a more massive object such as a brown dwarf or more than one planet.[7] The star is surrounded by a circumstellar disk from a distance of 0.2 to 4 AU, and again from 13 AU out to a few hundred AU, with evidence for a protoplanet forming at a distance of around 47 AU.[8]

HD 100546 b
Artist's impression of HD 100546 b
Orbital characteristics
6.5 AU (970,000,000 km)
StarHD 100546
Physical characteristics
Mean radius
6.9+2.7
−2.9[9] (Surrounding disk)[8][lower-alpha 1] RJ
Mass~20[6] MJ
Temperature932+193
−202[9] K
    HD 100546 c
    Orbital characteristics
    >12 AU
    StarHD 100546
      HD 100546

      This image from the NASA/ESA Hubble Space Telescope shows a visible light view of the outer dust around the young star HD 100546, with the newly discovered protoplanet positioned and marked by an orange spot. Artifacts from the brilliant central star dominate the inner part of this picture, which has been digitally subtracted. Black blobs are also artifacts.[1][2]
      Observation data
      Epoch J2000.0[3]      Equinox J2000.0[3]
      Constellation Musca
      Right ascension  11h 33m 25.441s[4]
      Declination −70° 11′ 41.24″[4]
      Apparent magnitude (V) 6.698[3]
      Characteristics
      Spectral type B9Vne[3]
      Details
      Age>10[5] Myr
      Astrometry
      Proper motion (μ) RA: −38.93 ± 0.36[4] mas/yr
      Dec.: 0.29 ± 0.38[4] mas/yr
      Parallax (π)10.32 ± 0.43[4] mas
      Distance320 ± 10 ly
      (97 ± 4 pc)
      Other designations
      KR Mus, HIP 56379,[3] SAO 251457, CD−69° 893
      Database references
      SIMBADdata

      Estimated to be around 10 million years old, it is at the upper age limit of the class of stars it belongs to—Herbig Ae/Be stars, and also the nearest example to the Solar System.[5]

      The HD 100546 planetary system
      Companion
      (in order from star)      		 Mass Semimajor axis
      (AU)      		 Orbital period
      (days)      		 Eccentricity Inclination Radius
      HD 100546 b >20 MJ 6.5 — — — < 6.9 RJ
      HD 100546 c — 13.5 — — — —

      Possible birth of new planet

      In 2013, researchers reported that they had found what seems to be a planet in the process of being formed, embedded in the star's large disc of gas and dust. If confirmed, it would represent the first opportunity to study the early stages of planet formation observationally.[10]

      HD 100546 b

      Evidence for a planetary companion to HD 100546 was gathered using the UVES echelle spectrograph at the VLT in Chile.[6] This confirms other data indicating a planetary companion. HD 100546 b might be the largest exoplanet discovered with a size of planet and surrounding disk[8] of around 6.9 RJ; the planet's size puts it near the border between a large planet and a brown dwarf.[9][6]

      Size comparison
      Sun HD 100546 b

      Protoplanetary material

      Coronagraphic optical observations with the Hubble Space Telescope [1][5] show complex spiral patterns in the circumstellar disk. The causes of these structures remain uncertain. The disk colors are similar to those derived for Kuiper Belt objects, suggesting that the same weathering processes are at work in HD 100546. The disk is fairly flat, consistent with an advanced evolutionary state.[1]

      Spectroscopic analysis of mid-IR data taken from OSCIR on the 4 m Blanco Telescope at Cerro Tololo Inter-American Observatory indicates the presence of a small particles (10–18 μm) containing silicates.[5] The material is found at distances out to 17 AU away from the star and has a temperature of approximately 227 K.[5]

      See also

      References
      1. Ardila, D. R.; Golimowski, D. A.; Krist, J. E.; Clmapin, M.; Ford, H. C.; Illingworth, G. D. (2007). "Hubble Space Telescope Advanced Camera for Surveys Coronagraphic Observations of the Dust Surrounding HD 100546". Astrophysical Journal. 665 (1): 512–534. arXiv:0704.1507. Bibcode:2007ApJ...665..512A. doi:10.1086/519296.
      2. "The Birth of a Giant Planet?". ESO. Retrieved 3 April 2013.
      3. "HD 100546". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 8 March 2018.
      4. van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.Vizier catalog entry
      5. Grady, C. A.; et al. (2001). "The Disk and Environment of the Herbig Be Star HD 100546". The Astronomical Journal. 122 (6): 3396–3406. Bibcode:2001AJ....122.3396G. doi:10.1086/324447.
      6. Acke, B.; van der Ancker, M. (November 2005). "Resolving the disk rotation of HD 97048 and HD 100546 in the [O I] 6300A line: evidence for a giant planet orbiting HD 100546". Astronomy and Astrophysics. 449 (267): 267. arXiv:astro-ph/0512562. Bibcode:2006A&A...449..267A. doi:10.1051/0004-6361:20054330.
      7. Mulders, Gijs D.; Paardekooper, Sijme-Jan; Pani´c, Olja; Dominik, Carsten; et al. (2013). "Planet or Brown Dwarf? Inferring the Companion Mass in HD 100546 from the Wall Shape using Mid-Infrared Interferometry". Astronomy & Astrophysics. 557A (A68): 10. arXiv:1306.4264. Bibcode:2013A&A...557A..68M. doi:10.1051/0004-6361/201220930.
      8. Quanz, Sasch P.; Amara, Adam; Meyer, Michael P.; Kenworthy, Matthew P.; et al. (2013). "A young protoplanet candidate embedded in the circumstellar disk of HD 100546". Astrophysical Journal. 766 (1). L1. arXiv:1302.7122. Bibcode:2013ApJ...766L...1Q. doi:10.1088/2041-8205/766/1/l1.
      9. Quanz, Sasch P.; Amara, Adam; Meyer, Michael P.; Kenworthy, Matthew P.; et al. (2014). "Confirmation and characterization of the protoplanet HD100546 b - Direct evidence for gas giant planet formation at 50 au". Astrophysical Journal. 807 (1). 64. arXiv:1412.5173. Bibcode:2015ApJ...807...64Q. doi:10.1088/0004-637X/807/1/64.
      10. "Is HD 100546 showing us the birth of a giant planet?". Science Codex. 2013-02-28. Archived from the original on 2013-03-05. Retrieved 2013-03-01.

      Notes
      1. The size of planet cannot be determined in size as flux from planet and disk are superimposed.

      Further reading
      • Butler, R. P.; et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal. 646 (1): 505–522. arXiv:astro-ph/0607493. Bibcode:2006ApJ...646..505B. doi:10.1086/504701.
      • Ecuvillon, A.; Israelian, G.; Pont, F.; Santos, N.; et al. (August 2006). "Kinematics of planet-host stars and their relation to dynamical streams in the solar neighbourhood". Astronomy and Astrophysics. 461 (171): 171–182. arXiv:astro-ph/0608669. Bibcode:2007A&A...461..171E. doi:10.1051/0004-6361:20065872.
      • Jones, B.; Sleep, P.; Underwood, D. (June 2006). "Habitability of known exoplanetary systems based on measured stellar properties". The Astrophysical Journal. 649 (1010): 1010–1019. arXiv:astro-ph/0603200. Bibcode:2006ApJ...649.1010J. doi:10.1086/506557.
      • Mandell, Avi M.; Raymond, Sean N.; Sigurdsson, Steinn (May 2007). "Formation of Earth-like Planets During and After Giant Planet Migration". The Astrophysical Journal. 660 (1): 823–844. arXiv:astro-ph/0701048. Bibcode:2007ApJ...660..823M. doi:10.1086/512759.
      • Marchi, S. (May 2007). "Extrasolar planet taxonomy: a new statistical approach". The Astrophysical Journal. 666 (1): 475–485. arXiv:0705.0910. Bibcode:2007ApJ...666..475M. doi:10.1086/519760.
      • Hedrick, C. H.; Doering, R.; Lee, K.-G.; Sosey, M.; et al. (December 2005). "The Circumstellar Dust Disk of HD 100546". Bulletin of the American Astronomical Society. 37 (4): 1167. Bibcode:2005AAS...207.1009H.

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