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Post Info TOPIC: Alpha Centauri D
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Title: Tentative planetary orbital constraints of some scenarios for the possible new Solar System object recently discovered with ALMA
Author: Lorenzo Iorio

Some of the scenarios envisaged for the possible new Solar System object, whose discovery with the ALMA facility has been recently claimed in the literature, are preliminarily put to the test by means of the orbital motions of some planets of the Solar System. It turns out that the current ranges of admissible values for any anomalous secular precession of the perihelion of Saturn, determined in the recent past with either the EPM2011 and the INPOP10a planetary ephemerides without modelling the action of such a potential new member of the Solar System, do not rule out the existence of a putative Neptune-like pointlike perturber at about 2500 au. Instead, both a super-Earth at some hundreds of au and a Jovian-type planet up to 4000 au are strongly disfavored. An Earth-sized body at 100 au would have a density as little as ~0.1-0.01 g cm^-3, while an unusually large Centaur or (Extreme) Trans Neptunian Object with linear size of 220-880 km at 12-25 au would have density much larger than ~1 g cm^-3.

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Astronomers Skeptical Over "Planet X" Claims

On December 8 researchers from Sweden and Mexico quietly submitted two papers to the prestigious journal Astronomy & Astrophysics, announcing their discovery of not one but two possible Planet X candidates. The quiet did not last for long. Even though neither paper has yet been accepted for peer-review and publication, the researchers uploaded both to the arXiv, a public online repository for preprint papers, where they appeared last night.
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Title: A new submm source within a few arcseconds of alpha Centauri: ALMA discovers the most distant object of the solar system
Author: R. Liseau, W. Vlemmings, E. O'Gorman, E. Bertone, M. Chavez, V. De la Luz

The understanding of the formation of stellar and planetary systems requires the understanding of the structure and dynamics of their outmost regions, where large bodies are not expected to form. Serendipitous searches for Sedna-like objects allows the observation of regions that are normally not surveyed. The Atacama Large Millimeter/submillimeter Array (ALMA) is particularly sensitive to point sources and it presents currently the only means to detect Sedna-like objects far beyond their perihelia. ALMA observations 10 months apart revealed a new blackbody point source that is apparently comoving with alpha Cen B. We exclude that source to be a sub-/stellar member of the alpha Centauri system, but argue that it is either an extreme TNO, a Super-Earth or a very cool brown dwarf in the outer realm of the solar system.

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