Context : Debris discs around main-sequence stars indicate the presence of larger rocky bodies .
The components of the nearby , solar-type binary \alpha { Cen } tauri have higher than solar metallicities , which is thought to promote giant planet formation .

Aims : We aim to determine the level of emission from debris around the stars in the \alpha { Cen } system .
This requires knowledge of their photospheres .
Having already detected the temperature minimum , T _ { min } , of \alpha { Cen A } at far-infrared wavelengths , we here attempt to do so also for the more active companion \alpha { Cen B } .
Using the \alpha { Cen } stars as templates , we study possible effects T _ { min } may have on the detectability of unresolved dust discs around other stars .

Methods : We use Herschel- PACS , Herschel- SPIRE , and APEX-LABOCA photometry to determine the stellar spectral energy distributions in the far infrared and submillimetre .
In addition , we use APEX-SHeFI observations for spectral line mapping to study the complex background around \alpha { Cen } seen in the photometric images .
Models of stellar atmospheres and of particulate discs , based on particle simulations and in conjunction with radiative transfer calculations , are used to estimate the amount of debris around these stars .

Results : For solar-type stars more distant than \alpha { Cen } , a fractional dust luminosity f _ { d } \equiv L _ { dust } / L _ { star } \sim 2 \times 10 ^ { -7 } could account for SEDs that do not exhibit the T _ { min } -effect .
This is comparable to estimates of f _ { d } for the Edgeworth-Kuiper belt of the solar system .
In contrast to the far infrared , slight excesses at the 2.5 \sigma level are observed at 24 \mu m for both \alpha { Cen A } and B , which , if interpreted to be due to zodiacal-type dust emission , would correspond to f _ { d } \sim ( 1 - 3 ) \times 10 ^ { -5 } , i.e .
some 10 ^ { 2 } times that of the local zodiacal cloud .
Assuming simple power law size distributions of the dust grains , dynamical disc modelling leads to rough mass estimates of the putative Zodi belts around the \alpha { Cen } stars , viz . \stackrel { < } { { } _ { \sim } } 4 \times 10 ^ { -6 } M _ { \leftmoon } of 4 to 1000 \mu m size grains , distributed according to n ( a ) \propto a ^ { -3.5 } .
Similarly , for filled-in T _ { min } emission , corresponding Edgeworth-Kuiper belts could account for \sim 10 ^ { -3 } M _ { \leftmoon } of dust .

Conclusions : Our far-infrared observations lead to estimates of upper limits to the amount of circumstellar dust around the stars \alpha { Cen A } and B .
Light scattered and/or thermally emitted by exo-Zodi discs will have profound implications for future spectroscopic missions designed to search for biomarkers in the atmospheres of Earth-like planets .
The far-infrared spectral energy distribution of \alpha { Cen B } is marginally consistent with the presence of a minimum temperature region in the upper atmosphere of the star .
We also show that an \alpha { Cen A } -like temperature minimum may result in an erroneous apprehension about the presence of dust around other , more distant stars .