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J/A+A/511/A63       V1118 Ori UBVRIJHK outburst light curves   (Audard+, 2010)

A multi-wavelength study of the young star V1118 Orionis in outburst. Audard M., Stringfellow G.S., Guedel M., Skinner S.L., Walter F.M., Guinan E.F., Hamilton R.T., Briggs K.R., Baldovin-Saavedra C. <Astron. Astrophys. 511, A63 (2010)> =2010A&A...511A..63A
ADC_Keywords: Stars, variable ; Stars, late-type ; Stars, pre-main sequence ; X-ray sources ; Photometry, UBVRIJKLMNH ; Accretion Keywords: accretion, accretion disks - infrared: stars - circumstellar matter - stars: coronae - stars: pre-main sequence - X-rays: stars Abstract: The accretion history of low-mass young stars is not smooth but shows spikes of accretion that can last from months and years to decades and centuries. Observations of young stars in outbursts can help us understand the temporal evolution of accreting stars and the interplay between the accretion disk and the stellar magnetosphere. The young late-type star V1118 Orionis was in outburst from 2005 to 2006. We followed the outburst with optical and near-infrared photometry. The X-ray emission was further probed with observations taken with XMM-Newton and Chandra during and after the outburst. In addition, we obtained mid-infrared photometry and spectroscopy with Spitzer at the peak of the outburst and in the post-outburst phase. The spectral energy distribution of V1118 Ori varied significantly over the course of the outburst. The optical flux showed the largest variations, most likely caused by enhanced emission by a hot spot. The hot spot dominated the optical and near-infrared emission at the peak of the outburst, while the disk emission dominated in the mid-infrared. The emission silicate feature in V1118 Ori is flat and does not vary in shape, but was slightly brighter at the peak of the outburst compared to the post-outburst spectrum. The X-ray flux correlated with the optical and infrared fluxes, indicating that accretion affected the magnetically active corona and the stellar magnetosphere. The thermal structure of the corona was variable with some indication of a cooling of the coronal temperature in the early phase of the outburst with a gradual return to normal values. Color-color diagrams in the optical and infrared showed variations during the outburst, with no obvious signature of reddening caused by circumstellar matter. Using Monte-Carlo realizations of star+disk+hotspot models to fit the spectral energy distributions in "quiescence" and at the peak of the outburst, we determined that the mass accretion rate varied from about 2.5x10-7M/yr to 1.0x10-6M/yr; in addition, the fractional area of the hotspot increased significantly. The multi-wavelength study of the V1118 Ori outburst helped us to understand the variations in spectral energy distributions and demonstrated the interplay between the disk and the stellar magnetosphere in a young, strongly accreting star. Description: Optical and near-infrared photometry taken by the ANDICAM imager on the SMARTS/CTIO 1.3m telescope, and by the Villanova telescope as part of the multi-wavelength campaign to observe the young EXor star V1118 Ori in outburst. The catalogues give magnitudes as a function of the modified Julian date. Objects: ------------------------------------------------------ RA (2000) DE Designation(s) ------------------------------------------------------ 05 34 44.7 -05 33 42 V1118 Ori = V* V1118 Ori ------------------------------------------------------ File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file tablea2.dat 93 155 SMARTS UBVRIJHK photometry tablea3.dat 38 35 Villanova VRI photometry
Byte-by-byte Description of file: tablea2.dat
Bytes Format Units Label Explanations
1- 5 I5 d MJD Modified Julian Date (JD-2400000.5) 7- 11 F5.2 mag Umag ? SMARTS Johnson U-band magnitude 13- 16 F4.2 mag e_Umag ? SMARTS Johnson U-band magnitude uncertainty 18- 22 F5.2 mag Bmag ? SMARTS Johnson B-band magnitude 24- 27 F4.2 mag e_Bmag ? SMARTS Johnson B-band magnitude uncertainty 29- 33 F5.2 mag Vmag ? SMARTS Johnson V-band magnitude 35- 38 F4.2 mag e_Vmag ? SMARTS Johnson V-band magnitude uncertainty 40- 44 F5.2 mag Rmag ? SMARTS Cousins R-band magnitude 46- 49 F4.2 mag e_Rmag ? SMARTS Cousins R-band magnitude uncertainty 51- 55 F5.2 mag Imag ? SMARTS Cousins I-band magnitude 57- 60 F4.2 mag e_Imag ? SMARTS Cousins I-band magnitude uncertainty 62- 66 F5.2 mag Jmag ? SMARTS J-band magnitude 68- 71 F4.2 mag e_Jmag ? SMARTS J-band magnitude uncertainty 73- 77 F5.2 mag Hmag ? SMARTS H-band magnitude 79- 82 F4.2 mag e_Hmag ? SMARTS H-band magnitude uncertainty 84- 88 F5.2 mag Kmag ? SMARTS K-band magnitude 90- 93 F4.2 mag e_Kmag ? SMARTS K-band magnitude uncertainty
Byte-by-byte Description of file: tablea3.dat
Bytes Format Units Label Explanations
1- 5 I5 d MJD Modified Julian Date (JD-2400000.5) 7- 11 F5.2 mag Vmag Villanova Bessel V-band magnitude 13- 16 F4.2 mag e_Vmag Villanova Bessel V-band magnitude uncertainty 18- 22 F5.2 mag Rmag Villanova Bessel R-band magnitude 24- 27 F4.2 mag e_Rmag Villanova Bessel R-band magnitude uncertainty 29- 33 F5.2 mag Imag Villanova Bessel I-band magnitude 35- 38 F4.2 mag e_Imag Villanova Bessel I-band magnitude uncertainty
Acknowledgements: Marc Audard, Marc.Audard(at)unige.ch
(End) M. Audard [ISDC & Obs. Geneve, Switzerland], P. Vannier [CDS] 29-Dec-2009
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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