Planetary System
The ecliptic of the 61 Virginis system, as inferred from its dust disc, is inclined to the Solar system at 77◦. The star itself is likely inclined at 72◦
In 1988, a study surmised that 61 Virginis was a "possible variable", but no companions were then found. A subsequent study, over eleven years, also failed to find any companion up to the mass of Jupiter and out to 3 AU.
On 14 December 2009, scientists announced the discovery of three planets with masses between 5 and 25 times that of Earth orbiting 61 Virginis. The three planets all orbit very near the star; when compared to the orbits of the planets in our solar system, all three would orbit inside that of Venus. The outermost of these three, d, has not yet been confirmed in the HARPS data.
A survey with the Spitzer Space Telescope revealed an excess of infrared radiation at a wavelength of 160 μm. This indicated the presence of a debris disk in orbit around the star. This disk was resolved at 70 μm. It was then thought to correspond to an inner radius of 96 AU from the star and outer radius at 195 AU; it is now constrained 30 to over 100 AU. The total mass of the disk is 5 × 10−5 the mass of the Earth.
On 27 November 2012, the European Space Agency declared that the debris disc (like Gliese 581's, recently found) has "at least 10 times" as many comets as does the Solar system.
As of 2012, "planets more massive than Saturn orbiting within 6 AU" were ruled out. The ESA has further ruled out Saturn-mass planets beyond that.
Additional data is needed to confirm the possibility of more sub-Saturn planets between 0.5 (really, 0.3) and 30 AU from the star. An Earth-mass planet in the star's habitable zone (which would still be too small to detect with current technology) remains possible.
| Companion |
Mass | Semimajor axis |
Orbital period |
Eccentricity | Radius |
|---|---|---|---|---|---|
| b | 5.3 ± 0.5 M⊕ | 0.050201 ± 0.000005 | 4.2150 ± 0.0006 | 0.12 ± 0.11 | — |
| c | 18.8 ± 1.1 M⊕ | 0.2175 ± 0.0001 | 38.021 ± 0.034 | 0.14 ± 0.06 | — |
| d | 23.7 ± 2.7 M⊕ | 0.476 ± 0.001 | 123.01 ± 0.55 | 0.35 ± 0.09 | — |
| Debris disk | 30–>100 AU | ||||
Read more about this topic: 61 Virginis
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