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J/A+A/584/A104 Luhman 16AB Lucky imaging photometry & astrometry (Mancini+ 2015)

Rotation periods and astrometric motions of the Luhman 16AB brown dwarfs by high-resolution lucky-imaging monitoring. Mancini L., Giacobbe P., Littlefair S.P., Southworth J., Bozza V., Damasso M., Dominik M., Hundertmark M., Jorgensen U.G., Juncher D., Popovas A., Rabus M., Rahvar S., Schmidt R.W., Skottfelt J., Snodgrass C., Sozzetti A., Alsubai K., Bramich D.M., Calchi Novati S., Ciceri S., D'Ago G., Figuera Jaimes R., Galianni P., Gu S.-H., Harpsoe K., Haugbolle T., Henning T., Hinse T.C., Kains N., Korhonen H., Scarpetta G., Starkey D., Surdej J., Wang X.-B., Wertz O. <Astron. Astrophys. 584, A104 (2015)> =2015A&A...584A.104M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple Keywords: binaries: visual - brown dwarfs - stars: variables: general - techniques: photometric - techniques: image processing Abstract: Photometric monitoring of the variability of brown dwarfs can provide useful information about the structure of clouds in their cold atmospheres. The brown-dwarf binary system Luhman 16AB is an interesting target for such a study, as its components stand at the L/T transition and show high levels of variability. Luhman 16AB is also the third closest system to the Solar system, allowing precise astrometric investigations with ground-based facilities. The aim of the work is to estimate the rotation period and study the astrometric motion of both components. We have monitored Luhman 16AB over a period of two years with the lucky-imaging camera mounted on the Danish 1.54 m telescope at La Silla, through a special i+z long-pass filter, which allowed us to clearly resolve the two brown dwarfs into single objects. An intense monitoring of the target was also performed over 16 nights, in which we observed a peak-to-peak variability of 0.20mag and 0.34mag for Luhman 16A and 16B, respectively. We used the 16-night time-series data to estimate the rotation period of the two components. We found that Luhman 16B rotates with a period of 5.1-hr, in very good agreement with previous measurements. For Luhman 16A, we report that it rotates slower than its companion and, even though we were not able to get a robust determination, our data indicate a rotation period of roughly 8-hr. This implies that the rotation axes of the two components are well aligned and suggests a scenario in which the two objects underwent the same accretion process. The 2-year complete dataset was used to study the astrometric motion of Luhman16AB. We predict a motion of the system that is not consistent with a previous estimate based on two months of monitoring, but cannot confirm or refute the presence of additional planetary-mass bodies in the system. Description: Photometric light curves and astrometric motion curves of Luhman 16A and Luhman 16B. Objects: ---------------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------------- 10 49 19.0 -53 19 10 Luhman 16A = ** LUH 16A 10 49 18.9 -53 19 09 Luhman 16B = ** LUH 16B ---------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file astrom.dat 119 24 Astrometry of Luhman 16A and Luhman 16B luh16a.dat 39 708 Photometric light curves of Luhman 16A luh16b.dat 39 708 Photometric light curves of Luhman 16B
Byte-by-byte Description of file: astrom.dat
Bytes Format Units Label Explanations
1- 9 F9.5 d JD Julian Date (JD-2456000.0) 11- 22 F12.10 deg Xi16A Measured Xi standard coordinate of Luhman 16A (1) 24- 36 F13.10 deg Eta16A Measured Eta standard coordinate of Luhman 16A (1) 38- 50 E13.8 deg e_Xi16A Uncertainty on Xi16A 52- 64 E13.8 deg e_Eta16A Uncertainty Eta16A 66- 77 F12.10 deg Xi16B Measured Xi standard coordinate of Luhman 16B (1) 79- 91 F13.10 deg Eta16B Measured Eta standard coordinate of Luhman 16B (1) 93-105 E13.8 deg e_Xi16B Uncertainty on Xi16B 107-119 E13.8 deg e_Eta16B Uncertainty Eta16B
Note (1): see equations in Sec 3.2.
Byte-by-byte Description of file: luh16a.dat luh16b.dat
Bytes Format Units Label Explanations
3- 15 F13.7 d BJD Barycentric JD for the midpoint of observation (TDB, BJD-2400000) 18- 27 F10.7 mag izmag PSF photometry i+z mag of Luhman 16 A 31- 39 F9.7 mag e_izmag Measurement error of the i+z band magnitude
Acknowledgements: Luigi Mancini, mancini(at) History: * 30-Nov-2015: First on-line version * 16-Feb-2016: Astrometric table added (from author)
(End) Luigi Mancini [MPIA, Germany], Patricia Vannier [CDS] 27-Oct-2015
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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