J/AJ/162/44 Near-IR spectrum of HIP 109427 with SCExAO/CHARIS (Steiger+, 2021) ================================================================================ SCExAO/MEC and CHARIS Discovery of a Low-mass, 6au Separation Companion to HIP109427 Using Stochastic Speckle Discrimination and High-contrast Spectroscopy Steiger S., Currie T., Brandt T.D., Guyon O., Kuzuhara M., Chilcote J., Groff T.D., Lozi J., Walter A.B., Fruitwala N., Bailey III J.I., Zobrist N., Swimmer N., Lipartito I., Smith J.P., Bockstiegel C., Meeker S.R., Coiffard G., Dodkins R., Szypryt P., Davis K.K., Daal M., Bumble B., Vievard S., Sahoo A., Deo V., Jovanovic N., Martinache F., Doppmann G., Tamura M., Kasdin N.J., Mazin B.A. =2021AJ....162...44S ================================================================================ ADC_Keywords: Stars, A-type; Exoplanets; Spectra, infrared Keywords: Direct imaging ; Astronomy data analysis ; Exoplanet detection methods ; Low mass stars Abstract: We report the direct imaging discovery of a low-mass companion to the nearby accelerating A star, HIP109427, with the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument coupled with the Microwave Kinetic Inductance Detector Exoplanet Camera (MEC) and CHARIS integral field spectrograph. CHARIS data reduced with reference star point spread function (PSF) subtraction yield 1.1-2.4{mu}m spectra. MEC reveals the companion in Y and J band at a comparable signal-to-noise ratio using stochastic speckle discrimination, with no PSF subtraction techniques. Combined with complementary follow-up Lp photometry from Keck/NIRC2, the SCExAO data favors a spectral type, effective temperature, and luminosity of M4-M5.5, 3000-3200K, and log_10_(L/L{odot})=-2.28_-0.04_^+0.04^, respectively. Relative astrometry of HIP109427B from SCExAO/CHARIS and Keck/NIRC2, and complementary Gaia-Hipparcos absolute astrometry of the primary favor a semimajor axis of 6.55+3.0-0.48au, an eccentricity of 0.54_-0.15_^+0.28^, an inclination of 66.7_-14_^+8.5^degrees, and a dynamical mass of 0.280_-0.059_^+0.18^M{sun}. This work shows the potential for extreme AO systems to utilize speckle statistics in addition to widely used postprocessing methods to directly image faint companions to nearby stars near the telescope diffraction limit. Description: In three epochs between 2020 July and December, we observed HIP109427 with the Subaru Telescope using the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) coupled to the Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS) and the Microwave Kinetic Inductance Detector Exoplanet Camera (MEC) and with the Keck II telescope using the NIRC2 camera. MEC data (2020 October 7) covers wavelengths over the Y and J passbands (0.95-1.4{mu}m) at a spectral resolution of ~3.3. We obtained CHARIS data in broadband (1.1-2.4{mu}m; 2020 July 31) at a resolution of ~18 or in the H band at a higher resolution (~70). Objects: -------------------------------------------------- RA (2000) DE Designation(s) -------------------------------------------------- 22 10 11.99 +06 11 52.3 HIP 109427 = HIP 109427 -------------------------------------------------- File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file fig3a.dat 35 19 SCExAO/CHARIS spectra for HIP 109427 B from H-band data fig3b.dat 35 22 SCExAO/CHARIS spectra for HIP 109427 B extracted from broadband data -------------------------------------------------------------------------------- See also: I/311 : Hipparcos, the New Reduction (van Leeuwen, 2007) J/AJ/129/2420 : Proper motion derivatives of binaries (Makarov+, 2005) J/AJ/132/161 : NStars project: The southern sample. I. (Gray+, 2006) J/MNRAS/389/585 : Fundamental parameters of M dwarfs (Casagrande+, 2008) J/ApJS/208/9 : Intrinsic colors & temperatures of PMS stars (Pecaut+, 2013) J/MNRAS/437/1216 : VAST Survey. A-type stars multiplicity (De Rosa+, 2014) J/ApJ/804/146 : Atmospheric parameters for nearby B-F stars (David+, 2015) J/ApJS/219/33 : BANYAN. VII. Candidate YMG members from BASS (Gagne+, 2015) J/other/Sci/350.64 : 51 Eri b near-infrared spectrum (Macintosh+, 2015) J/A+A/605/L9 : NIR spectrum of exoplanet HIP 65426b (Chauvin+, 2017) J/ApJ/856/23 : BANYAN. XI. The BANYAN {Sigma} algorithm (Gagne+, 2018) J/AJ/156/286 : The LEECH exoplanet imaging survey (Stone+, 2018) J/AJ/158/13 : The first 300 stars observed by the GPIES (Nielsen+, 2019) Byte-by-byte Description of file: fig3[ab].dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 9 F9.7 um lambda Wavelength 11- 17 F7.4 mJy Flux Flux density 19- 26 F8.5 mJy e_Flux Mean error on flux density 28- 35 F8.5 --- SNR Signal to Noise Ratio -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Prepared by [AAS], Coralie Fix [CDS], 15-Nov-2021