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The infrared void in the Lupus dark clouds
revisited: a polarimetric approach
(Alves & Franco, 2006)
The infrared void in the Lupus dark clouds
revisited: a polarimetric approach
(Alves & Franco, 2006)
F. O. AlvesG. A. P. FrancoPhysics Departament, ICEX, UFMG, Belo Horizonte, Brazil
F. O. AlvesG. A. P. FrancoPhysics Departament, ICEX, UFMG, Belo Horizonte, Brazil
Lupus dark clouds and Lupus 1
Lupus dark clouds and Lupus 1
Optical extinction: Cambresy, 1999Optical extinction: Cambresy, 1999
100 100 m IRAS emisisonm IRAS emisison
Main purposesMain purposes
Starlight polarization by dust to improve the distance to the low-mass star forming cloud Lupus 1
Confirm the existence of a low emission region towards the cloud complex.
Describe the solar neighborhood and, particularly, the Loop 1-Local Bubble interface
Starlight polarization by dust to improve the distance to the low-mass star forming cloud Lupus 1
Confirm the existence of a low emission region towards the cloud complex.
Describe the solar neighborhood and, particularly, the Loop 1-Local Bubble interface
InstrumentationInstrumentation
B-band CCD polarimetry (8’ x 8’)
B-band CCD polarimetry (8’ x 8’)
Polarimetric unit (Magalhães et al, 1996)Polarimetric unit (Magalhães et al, 1996) IAG 0.60m IAG 0.60m telescopetelescope
Observational techniqueObservational technique
44 nights from 2001 to 2005 at Observatório do Pico dos Dias (LNA/MCT, Brazil).
131 Hipparcos stars with trigonometric parallaxes H ≥ 4mas (≤ 250 pc).
Selection criterion: /H ≤ 1/3 Calibration targets: polarized and unpolarized standart stars (<Q> ~ -0.007 and <U> ~ -0.006 per cent small instrumental polarization).
44 nights from 2001 to 2005 at Observatório do Pico dos Dias (LNA/MCT, Brazil).
131 Hipparcos stars with trigonometric parallaxes H ≥ 4mas (≤ 250 pc).
Selection criterion: /H ≤ 1/3 Calibration targets: polarized and unpolarized standart stars (<Q> ~ -0.007 and <U> ~ -0.006 per cent small instrumental polarization).
Standart starsStandart stars
The parallax-polarization diagram
The parallax-polarization diagram
Lupus 1 and surroundingsLupus 1 and surroundings
The parallax-polarization diagram
The parallax-polarization diagram
Low emission region (cavity)Low emission region (cavity)
The polarization mapThe polarization map
Comparison to previous work
Comparison to previous work
Colour excess data by Franco, 2002Colour excess data by Franco, 2002
ResultsResults
Distribution of linear polarization as a function of distance shows the same pattern found for the reddening-distance diagram;
Parallax-polarization diagram indicates low polarization values up to 130-150 pc, where the dust associated to Lupus 1 may be responsible for the sharp increasing in the polarization values;
Reddening- and polarization- distance diagrams suggest the existence of a region cleaned from dust in the Lupus dark clouds;
Material associated to the Loop 1-Local Bubble interface may be at 60-100 pc.
Distribution of linear polarization as a function of distance shows the same pattern found for the reddening-distance diagram;
Parallax-polarization diagram indicates low polarization values up to 130-150 pc, where the dust associated to Lupus 1 may be responsible for the sharp increasing in the polarization values;
Reddening- and polarization- distance diagrams suggest the existence of a region cleaned from dust in the Lupus dark clouds;
Material associated to the Loop 1-Local Bubble interface may be at 60-100 pc.
Pipe nebulaPipe nebula
Distance from the Sun: 145 ± 16 pc (Alves & Franco, in preparation).Distance from the Sun: 145 ± 16 pc (Alves & Franco, in preparation).