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Herschel discovery of a new class of cold, faint debris discs

C. Eiroa ; J. P. Marshall ; A. Mora ; A. V. Krivov ; B. Montesinos ; O. Absil ; D. Ardila ; M. Arevalo ; J. C. Augereau ; A. Bayo ; W. Danchi ; C. del Burgo ; S. Ertel ; M. Fridlund ; B. M. Gonzalez-Garcia ; A. M. Heras ; J. Lebreton ; René Liseau (Institutionen för rymd- och geovetenskap, Radioastronomi och astrofysik) ; J. Maldonado ; G. Meeus ; D. Montes ; G. L. Pilbratt ; A. Roberge ; J. Sanz-Forcada ; K. Stapelfeldt ; P. Thebault ; G. J. White ; S. Wolf
Astronomy and Astrophysics (0004-6361). Vol. 536 (2011),
[Artikel, refereegranskad vetenskaplig]

We present Herschel PACS 100 and 160 mu m observations of the solar-type stars alpha Men, HD 88230 and HD 210277, which form part of the FGK stars sample of the Herschel open time key programme (OTKP) DUNES (DUst around NEarby S tars). Our observations show small infrared excesses at 160 mu m for all three stars. HD 210277 also shows a small excess at 100 mu m, while the 100 mu m fluxes of alpha Men and HD 88230 agree with the stellar photospheric predictions. We attribute these infrared excesses to a new class of cold, faint debris discs. Both alpha Men and HD 88230 are spatially resolved in the PACS 160 mu m images, while HD 210277 is point-like at that wavelength. The projected linear sizes of the extended emission lie in the range from similar to 115 to <= 250 AU. The estimated black body temperatures from the 100 and 160 mu m fluxes are less than or similar to 22 K, and the fractional luminosity of the cold dust is L(dust)/L(*) similar to 10(-6), close to the luminosity of the solar-system's Kuiper belt. These debris discs are the coldest and faintest discs discovered so far around mature stars, so they cannot be explained easily invoking "classical" debris disc models.

Nyckelord: circumstellar matter, planetary systems, stars: individual: alpha Men, (HIP 29271), stars: individual: HD 88230 (HIP 49908), stars: individual:, HD 210277 (HIP 109378), main-sequence stars, disks, planets, images, pacs

Denna post skapades 2012-02-17. Senast ändrad 2015-07-10.
CPL Pubid: 155192


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