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.
Epoch J2000.0 Equinox J2000.0
|Right ascension||11h 33m 25.441s|
|Declination||−70° 11′ 41.24″|
|Apparent magnitude (V)||6.698|
|Proper motion (μ)|| RA: −38.93 ± 0.36 mas/yr |
Dec.: 0.29 ± 0.38 mas/yr
|Parallax (π)||10.32 ± 0.43 mas|
|Distance||320 ± 10 ly |
(97 ± 4 pc)
HD 100546, also known as KR Muscae, is a star 320 light-years from Earth. It is orbited by an approximately 20 MJ exoplanet at 6.5 AU, 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. 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.
Artist's impression of HD 100546 b
|6.5 AU (970,000,000 km)|
−2.9 (Surrounding disk)[a] RJ
(in order from star)
|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.
HD 100546 b
Evidence for a planetary companion to HD 100546 was gathered using the UVES echelle spectrograph at the VLT in Chile. 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 of around 6.9 RJ; the planet's size puts it near the border between a large planet and a brown dwarf.
However, the position where HD 100546 b was detected was inside compared with the gap between the inner and outer disks, and outside compared with the central cavity, so the validity of the planet was shown from the characteristics of the star disk. There was a discrepancy with the discussion. As a result of further detailed observation of the position where HD 100546 b was detected, the light source identified as HD 100546 b appeared to be a point light source in the analysis under specific conditions, but in many cases it became a more diffuse structure.
|Sun||HD 100546 b|
Coronagraphic optical observations with the Hubble Space Telescope  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.
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. The material is found at distances out to 17 AU away from the star and has a temperature of approximately 227 K.
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- Astronomy picture of the day - May 2, 2001