J/ApJ/847/131 KIC 8462852 one-yr obs. from UV to MIR (Meng+, 2017) ================================================================================ Extinction and the dimming of KIC 8462852. Meng H.Y.A., Rieke G., Dubois F., Kennedy G., Marengo M., Siegel M., Su K., Trueba N., Wyatt M., Boyajian T., Lisse C.M., Logie L., Rau S., Vanaverbeke S. =2017ApJ...847..131M ================================================================================ ADC_Keywords: Stars, peculiar; Photometry, ultraviolet; Photometry, UBVRI; Photometry, infrared Keywords: circumstellar matter; dust, extinction; stars: individual (KIC 8462852); stars: peculiar Abstract: To test alternative hypotheses for the behavior of KIC 8462852, we obtained measurements of the star over a wide wavelength range from the UV to the mid- infrared from 2015 October through 2016 December, using Swift, Spitzer and AstroLAB IRIS. The star faded in a manner similar to the long-term fading seen in Kepler data about 1400 days previously. The dimming rate for the entire period reported is 22.1+/-9.7mmag/yr in the Swift wavebands, with amounts of 21.0+/-4.5mmag in the ground-based B measurements, 14.0+/-4.5mmag in V, and 13.0+/-4.5 in R, and a rate of 5.0+/-1.2mmag/yr averaged over the two warm Spitzer bands. Although the dimming is small, it is seen at >~3{sigma} by three different observatories operating from the UV to the IR. The presence of long-term secular dimming means that previous spectral energy distribution models of the star based on photometric measurements taken years apart may not be accurate. We find that stellar models with Teff=7000-7100K and A_V_~0.73 best fit the Swift data from UV to optical. These models also show no excess in the near-simultaneous Spitzer photometry at 3.6 and 4.5{mu}m, although a longer wavelength excess from a substantial debris disk is still possible (e.g., as around Fomalhaut). The wavelength dependence of the fading favors a relatively neutral color (i.e., R_V_>~5, but not flat across all the bands) compared with the extinction law for the general interstellar medium (R_V_=3.1), suggesting that the dimming arises from circumstellar material. Description: KIC 8462852 was first observed by Swift/UVOT on 2015 October 22 and then approximately every three days from 2015 December 4 to 2016 March 27. X-ray data were obtained simultaneously with the Swift/XRT. Optical observations in B, V, and R bands were taken with the 684mm aperture Keller F4.1 Newtonian New Multi-Purpose Telescope (NMPT) of the public observatory AstroLAB IRIS, Zillebeke, Belgium. The B, V, and R filters are from Astrodon Photometrics, and have been shown to reproduce the Johnson/Cousins system closely. The earliest observation was made on 2015 September 29. There is a gap in time coverage from 2016 January 8 to June 8. We report the observations through 2016 December. Our first Spitzer/IRAC observation was executed on 2016 January 16. There is a gap in the time baseline of the monitoring in the period from 2016 April to July (from MJD 57475 to 57605) when KIC 8462852 was out of the visibility window of Spitzer. Objects: ---------------------------------------------------------------- RA (ICRS) DE Designation(s) ---------------------------------------------------------------- 20 06 15.46 +44 27 24.8 KIC 8462852 = NAME Boyajian's Star ---------------------------------------------------------------- File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . this file table1.dat 53 367 Swift/UVOT photometry of KIC 8462852 table4.dat 49 13 Selected high-quality NMPT/IRIS BVR photometry table6.dat 39 15 Spitzer photometry -------------------------------------------------------------------------------- See also: B/swift : Swift Master Catalog (HEASARC, 2004-) B/vsx : AAVSO International Variable Star Index VSX (Watson+, 2006-2014) V/133 : Kepler Input Catalog (Kepler Mission Team, 2009) II/349 : The Pan-STARRS release 1 (PS1) Survey - DR1 (Chambers+, 2016) I/345 : Gaia DR2 (Gaia Collaboration, 2018) J/ApJS/179/451 : IR excesses for protoplanetary disks (Kenyon+, 2008) J/MNRAS/397/1177 : Swift-XRT observations of GRBs (Evans+, 2009) J/ApJ/737/73 : IR extinction toward the Galactic Centre (Fritz+, 2011) J/PASP/124/1279 : Q3 Kepler's combined photometry (Christiansen+, 2012) J/ApJS/208/9 : Intrinsic colors & temperatures of PMS stars (Pecaut+, 2013) J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014) J/ApJ/805/77 : Spitzer 3.6 and 4.5um monitoring of 5 stars (Meng+, 2015) J/ApJ/813/100 : Deep GALEX NUV survey of the Kepler field I. (Olmedo+, 2015) J/ApJ/823/108 : A dust model for bet Pic from 0.58-870um (Ballering+, 2016) Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 4 A4 --- Filt Filter (u, v, uvw1, uvm2 or uvw2) 6- 14 F9.3 d MJD Modified Julian Date 16- 21 F6.3 mag raw-mag [11.8/15] Raw magnitude 23- 27 F5.3 mag e_raw-mag [0.02/0.07] Uncertainty in raw-mag 29- 34 F6.3 mag cor-mag [11.8/15.2] Corrected magnitude 36- 40 F5.3 mag e_cor-mag [0.02/0.2] Uncertainty in cor-mag 42- 47 F6.3 mag rel-mag [-0.4/0.3] Relative comparison magnitude (1) 49- 53 F5.3 mag e_rel-mag [0.01/0.2] Uncertainty in rel-mag -------------------------------------------------------------------------------- Note (1): Average brightening of the comparison star measurements. -------------------------------------------------------------------------------- Byte-by-byte Description of file: table4.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 10 F10.2 d JD Julian Date 12- 17 F6.3 mag Bmag [12.3/12.4] AstroLAB IRIS B band magnitude 19- 23 F5.3 mag e_Bmag [0.003/0.02] Uncertainty in Bmag (1) 25- 30 F6.3 mag Vmag [11.8/11.9] AstroLAB IRIS V band magnitude 32- 36 F5.3 mag e_Vmag [0.003/0.02] Uncertainty in Vmag (1) 38- 43 F6.3 mag Rmag [11.4/11.5] AstroLAB IRIS R band magnitude 45- 49 F5.3 mag e_Rmag [0.003/0.02] Uncertainty in Rmag (1) -------------------------------------------------------------------------------- Note (1): Combined rms errors of the mean, i.e. rms scatter root of (n-1) where n is the number of measurements. -------------------------------------------------------------------------------- Byte-by-byte Description of file: table6.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 9 F9.3 d MJD [57040.3/57814] Modified Julian Date 11- 17 F7.4 mag 3.6mag [10.4/10.5] Spitzer/IRAC 3.6um photometry 19- 24 F6.4 mag e_3.6mag [0.001/0.003] Uncertainty in 3.6mag 26- 32 F7.4 mag 4.5mag [10.4/10.5] Spitzer/IRAC 4.5um photometry 34- 39 F6.4 mag e_4.5mag [0.001/0.003] Uncertainty in 4.5mag -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Prepared by [AAS], Emmanuelle Perret [CDS] 05-Jun-2018