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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
View of the dust disc around the young star HD 100546.jpg
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]
Spectral type B9Vne[3]
Age>10[5] Myr
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
HD 100546 b
Artist's impression of a gas giant planet forming in the disc around the young star HD 100546.jpg
Artist's impression of HD 100546 b
Orbital characteristics
6.5 AU (970,000,000 km)
StarHD 100546
Physical characteristics
Mean radius
[9] (Surrounding disk)[8][a] RJ
Mass~20[6] MJ
[9] K
HD 100546 c
Orbital characteristics
>12 AU
StarHD 100546

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
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
b >20 MJ 6.5 < 6.9 RJ
c 13.5


Possible birth of new planetEdit

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 bEdit

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 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 materialEdit

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 alsoEdit


  1. ^ a b c 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. ^ a b c d "HD 100546". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 8 March 2018.
  4. ^ a b c d e f 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. ^ a b c d e 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. ^ a b c d 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. ^ a b c 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. ^ a b c 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.


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

Further readingEdit

External linksEdit