No Clear, Direct Evidence for Multiple Protoplanets Orbiting LkCa 15: LkCa 15 bcd are Likely Inner Disk Signals
Mulders, Gijs D.
Brandt, Timothy D.
Kasdin, N. Jeremy
Groff, Tyler D.
McElwain, Michael W.
AffiliationUniv Arizona, Steward Observ
Univ Arizona, Coll Opt Sci
Keywordsinstrumentation: high angular resolution
stars: individual (LkCa 15)
stars: variables: T Tauri, Herbig Ae/Be
techniques: image processing
MetadataShow full item record
PublisherIOP PUBLISHING LTD
CitationThayne Currie et al 2019 ApJL 877 L3
JournalASTROPHYSICAL JOURNAL LETTERS
Rights© 2019. The American Astronomical Society. All rights reserved.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at email@example.com.
AbstractTwo studies utilizing sparse aperture-masking (SAM) interferometry and H-alpha differential imaging have reported multiple Jovian companions around the young solar-mass star, LkCa 15 (LkCa 15 bcd): the first claimed direct detection of infant, newly formed planets ("protoplanets"). We present new near-infrared direct imaging/spectroscopy from the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system coupled with Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS) integral field spectrograph and multi-epoch thermal infrared imaging from Keck/NIRC2 of LkCa 15 at high Strehl ratios. These data provide the first direct imaging look at the same wavelengths and in the same locations where previous studies identified the LkCa 15 protoplanets, and thus offer the first decisive test of their existence. The data do not reveal these planets. Instead, we resolve extended emission tracing a dust disk with a brightness and location comparable to that claimed for LkCa 15 bcd. Forward-models attributing this signal to orbiting planets are inconsistent with the combined SCExAO/CHARIS and Keck/NIRC2 data. An inner disk provides a more compelling explanation for the SAM detections and perhaps also the claimed H-alpha detection of LkCa 15 b. We conclude that there is currently no clear, direct evidence for multiple protoplanets orbiting LkCa 15, although the system likely contains at least one unseen Jovian companion. To identify Jovian companions around LkCa 15 from future observations, the inner disk should be detected and its effect modeled, removed, and shown to be distinguishable from planets. Protoplanet candidates identified from similar systems should likewise be clearly distinguished from disk emission through modeling.
VersionFinal published version
SponsorsNASA Senior Postdoctoral Fellowship; NASA/Keck grant [LK-2663-948181]; CONICYT-FONDECYT ; project CONICYT PAI/Concurso Nacional Insercion en la Academia, convocatoria 2015 ; JSPS KAKENHI [18H05442, 15H02063]; National Aeronautics and Space Administration; Subaru Time Allocation Committe; NASA/Keck Time Allocation Committe