2025/12/01 by Mona El Morsy, Morsy, Mona El, Thayne Currie +63 · 1 voice · 3 citations
Physics and Astronomy · #Stellar, planetary, and galactic studies #Astrophysics and Star Formation Studies #Astronomy and Astrophysical Research
paper · pdf · doi:10.3847/2041-8213/ae195f
Abstract We present the OASIS survey program discovery of a substellar companion orbiting the young A1V star HIP 71618, detected using precision astrometry from Gaia and Hipparcos and high-contrast imaging with SCExAO/CHARIS and Keck/NIRC2. Atmospheric modeling favors a spectral type of M5–M8 and a temperature of ∼2700 ± 100 K. Dynamical modeling constrains HIP 71618 B’s mass to be <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>60</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>21</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>27</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> M Jup or <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>65</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>29</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>54</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> M Jup , depending on the adopted companion mass prior. It has a nearly-edge-on 11 au orbit with high eccentricity. HIP 71618 B will be located within the Roman Coronagraph’s dark-hole region during the instrument’s technological demonstration phase. A high-signal-to-noise-ratio detection of HIP 71618 B at 575 nm would demonstrate a 5 σ contrast of 10 −7 or better. The system is also located within or very close to the Roman Coronagraph’s Continuous Viewing Zone—near multiple candidate reference stars for dark-hole digging—and its primary is bright ( V ≈ 5). The suitability of HIP 71618 as a potential Roman Coronagraph target for demonstrating the instrument’s core requirement (TTR5) should motivate the timely deep vetting of candidate reference stars.