Medium Resolution Spectroscopy of Boyajian's Star (KIC 8462852)
ATel #10406; I. A. Steele, G. P. Lamb, C. M. Copperwheat, H. E. Jermak (Liverpool JMU)
on 20 May 2017; 14:50 UT
Credential Certification: Iain Steele (firstname.lastname@example.org)
ATel #10405 reports that a several percent dip in the brightness of KIC 8462852 is underway.
We report medium resolution spectroscopy (R=2500) taken with the FRODOSpec fibre fed integral field spectrograph of the 2.0 meter Liverpool Telescope, La Palma obtained on 20th May 2017 starting at 01:20UT. Three 600 second exposures were obtained, giving a total integration time of 1800 seconds. The wavelength range was 5800 - 9400 Angstroms.
The spectrum is compared with a reference spectrum obtained "out of dip" on 4th July 2016 with an identical instrumental setup and exposure time.
In an initial analysis we find no difference between the two spectra apart from in features that are attributable to the expected variable telluric absorption features in the Earth's atmosphere.
Excerpts of the spectra in the region of H-alpha (https://www.dropbox.com/s/u11lv7d5opeo0rr/KIC-halpha.png?dl=0) and the IR Calcium Triplet (https://www.dropbox.com/s/isev1ymggilx4hl/KIC-Ca.png?dl=0) are shown (the different ripples in the two Ca spectra are due to CCD fringing in the detector). Taking the ratio of the two spectra gives standard deviations per pixel of 2 percent of the continuum level in the H-alpha region and 3 percent in the Calcium triplet region, with no evidence of any changes visible between the two epochs in the lines.
We will continue to monitor the object. We would like to thank Drs Klaas Wiersema (Leicester) and Grant Kennedy (Cambridge) for bringing the notification of the current dip to our attention.