OASIS Survey Direct Imaging and Astrometric Discovery of HIP 71618 B: A Substellar Companion Suitable for the Roman Coronagraph Technology Demonstration*
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.
Authors
- Timothy D. Brandt (ORCID: https://orcid.org/0000-0003-2630-8073)
- Christian Marois (ORCID: https://orcid.org/0000-0002-4164-4182)
- M. Janson (ORCID: https://orcid.org/0000-0001-8345-593X)
- N. Jeremy Kasdin (ORCID: https://orcid.org/0000-0002-6963-7486)
- Robert J. De Rosa (ORCID: https://orcid.org/0000-0002-4918-0247)
- Tyler D. Groff (ORCID: https://orcid.org/0000-0001-5978-3247)
- William Thompson (ORCID: https://orcid.org/0000-0001-5684-4593)
- Sabina Sagynbayeva (ORCID: https://orcid.org/0000-0002-6650-3829)
- Danielle Bovie (ORCID: https://orcid.org/0000-0001-7967-9922)
- Thayne Currie (ORCID: https://orcid.org/0000-0002-7405-3119)
- E. Nielsen (ORCID: https://orcid.org/0000-0001-6975-9056)
- Olivier Guyon (ORCID: https://orcid.org/0000-0002-1097-9908)
- Julien Lozi (ORCID: https://orcid.org/0000-0002-3047-1845)
- Taylor Tobin (ORCID: https://orcid.org/0000-0001-8103-5499)
- Naoshi Murakami (ORCID: https://orcid.org/0000-0001-6177-1333)
- Bertrand Mennesson (ORCID: https://orcid.org/0000-0003-4205-4800)
- A. Zurlo (ORCID: https://orcid.org/0000-0002-5903-8316)
- Dillon Peng
- Jeffrey Chilcote (ORCID: https://orcid.org/0000-0001-6305-7272)
- Masayuki Kuzuhara (ORCID: https://orcid.org/0000-0002-4677-9182)
- Mona El Morsy (ORCID: https://orcid.org/0000-0001-9441-7656)
- Sébastien Vievard (ORCID: https://orcid.org/0000-0003-4018-2569)
- Motohide Tamura (ORCID: https://orcid.org/0000-0002-6510-0681)
- Nour Skaf (ORCID: https://orcid.org/0000-0002-9372-5056)
- Brianna Lacy (ORCID: https://orcid.org/0000-0002-9420-4455)
- Vincent Déo (ORCID: https://orcid.org/0000-0003-4514-7906)
- Taichi Uyama (ORCID: https://orcid.org/0000-0002-6879-3030)
- Yiting Li (ORCID: https://orcid.org/0000-0002-6845-9702)
- Qier An (ORCID: https://orcid.org/0000-0003-0115-547X)
- Miles Lucas (ORCID: https://orcid.org/0000-0001-6341-310X)
- Ziying Gu
Publication Details
- Journal
- The Astrophysical Journal Letters
- Published
- 2025-12-03
- DOI
- https://doi.org/10.3847/2041-8213/ae195f
- Citations
- 1
- Primary Topic
- Stellar, planetary, and galactic studies
- Type
- article
- Field-Weighted Citation Impact
- 1.15