Paper

Exploring the directly imaged HD 1160 system through spectroscopic characterisation and high-cadence variability monitoring

Derkink, Annelotte, Wang, Ji, Doelman, David S, Skemer, Andrew J, Ertel, Steve, Birkby, Jayne L, Leisenring, Jarron M, Snik, Frans, Backs, Frank, Kenworthy, Matthew A, Charbonneau, David, Biller, Beth A, Ilyin, Ilya, Sutlieff, Ben J, Bohn, Alexander J, Woodward, Charles E, Strassmeier, Klaus G, Stone, Jordan M

2024

Overview

The time variability and spectra of directly imaged companions provide insight into their physical properties and atmospheric dynamics. We present follow-up R~40 spectrophotometric monitoring of red companion HD 1160 B at 2.8-4.2 \\(\\)m using the double-grating 360 vector Apodizing Phase Plate (dgvAPP360) coronagraph and ALES integral field spectrograph on the Large Binocular Telescope Interferometer. We use the recently developed technique of gvAPP-enabled differential spectrophotometry to produce differential light curves for HD 1160 B. We reproduce the previously reported ~3.2 h periodic variability in archival data, but detect no periodic variability in new observations taken the following night with a similar 3.5% level precision, suggesting rapid evolution in the variability of HD 1160 B. We also extract complementary spectra of HD 1160 B for each night. The two are mostly consistent, but the companion appears fainter on the second night between 3.0-3.2 \\(\\)m. Fitting models to these spectra produces different values for physical properties depending on the night considered. We find an effective temperature T\\(_eff\\) = 2794\\(^+115_-133\\) K on the first night, consistent with the literature, but a cooler T\\(_eff\\) = 2279\\(^+79_-157\\) K on the next. We estimate the mass of HD 1160 B to be 16-81 M\\(_Jup\\), depending on its age. We also present R = 50,000 high-resolution optical spectroscopy of host star HD 1160 A obtained simultaneously with the PEPSI spectrograph. We reclassify its spectral type to A1 IV-V and measure its projected rotational velocity v sin i = 96\\(^+6_-4\\) km s\\(^-1\\). We thus highlight that gvAPP-enabled differential spectrophotometry can achieve repeatable few percent level precision and does not yet reach a systematic noise floor, suggesting greater precision is achievable with additional data or advanced detrending techniques.

• Publisher: Cornell University Library, arXiv.org
• Subject: Coronagraphs / Light curve / Monitoring / Night / Phase plates / Physical properties / Rotation / Rotational spectra / Spectrophotometry / Spectrum analysis