Astrometric and photometric characterization of \(\eta\) Tel B combining two decades of observations

• Published in: arXiv.org
• Main Authors: Nogueira, P H, Lazzoni, C, Zurlo, A, Bhowmik, T, Donoso-Oliva, C, Desidera, S, Milli, J, Pérez, S, Delorme, P, Fernadez, A, Langlois, M, Petrus, S, Cabrera-Vives, G, Chauvin, G
• Format: Paper
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 08.05.2024
• Subjects: A stars; Eccentric orbits; Photometry; Position measurement; Separation
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2405.04723

\(\eta\) Tel is an 18 Myr system with a 2.09 M\(_{\odot}\) A-type star and an M7-M8 brown dwarf companion, \(\eta\) Tel B, separated by 4.2'' (208 au). High-contrast imaging campaigns over 20 years have enabled orbital and photometric characterization. \(\eta\) Tel B, bright and on a wide orbit, is ideal for detailed examination. We analyzed three new SPHERE/IRDIS coronagraphic observations to explore \(\eta\) Tel B's orbital parameters, contrast, and surroundings, aiming to detect a circumplanetary disk or close companion. Reduced IRDIS data achieved a contrast of 1.0\(\times 10^{-5}\), enabling astrometric measurements with uncertainties of 4 mas in separation and 0.2 degrees in position angle, the smallest so far. With a contrast of 6.8 magnitudes in the H band, \(\eta\) Tel B's separation and position angle were measured as 4.218'' and 167.3 degrees, respectively. Orbital analysis using Orvara code, considering Gaia-Hipparcos acceleration, revealed a low eccentric orbit (e \(\sim\) 0.34), inclination of 81.9 degrees, and semi-major axis of 218 au. \(\eta\) Tel B's mass was determined to be 48 \MJup, consistent with previous calculations. No significant residual indicating a satellite or disk around \(\eta\) Tel B was detected. Detection limits ruled out massive objects around \(\eta\) Tel B with masses down to 1.6 \MJup at a separation of 33 au.