TY - JOUR
T1 - No Clear, Direct Evidence for Multiple Protoplanets Orbiting LkCa 15
T2 - LkCa 15 bcd are Likely Inner Disk Signals
AU - Currie, Thayne
AU - Marois, Christian
AU - Cieza, Lucas
AU - Mulders, Gijs D.
AU - Lawson, Kellen
AU - Caceres, Claudio
AU - Rodriguez-Ruiz, Dary
AU - Wisniewski, John
AU - Guyon, Olivier
AU - Brandt, Timothy D.
AU - Kasdin, N. Jeremy
AU - Groff, Tyler D.
AU - Lozi, Julien
AU - Chilcote, Jeffrey
AU - Hodapp, Klaus
AU - Jovanovic, Nemanja
AU - Martinache, Frantz
AU - Skaf, Nour
AU - Lyra, Wladimir
AU - Tamura, Motohide
AU - Asensio-Torres, Ruben
AU - Dong, Ruobing
AU - Grady, Carol
AU - Gerard, Benjamin
AU - Fukagawa, Misato
AU - Hand, Derek
AU - Hayashi, Masahiko
AU - Henning, Thomas
AU - Kudo, Tomoyuki
AU - Kuzuhara, Masayuki
AU - Kwon, Jungmi
AU - McElwain, Michael W.
AU - Uyama, Taichi
N1 - Publisher Copyright:
© 2019. The American Astronomical Society. All rights reserved.
PY - 2019/5/20
Y1 - 2019/5/20
N2 - Two studies utilizing sparse aperture-masking (SAM) interferometry and Hα 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 Hα 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.
AB - Two studies utilizing sparse aperture-masking (SAM) interferometry and Hα 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 Hα 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.
KW - Herbig Ae/Be
KW - Herbig Ae/Be
KW - instrumentation: high angular resolution
KW - planetary systems
KW - stars: individual (LkCa 15)
KW - stars: variables: T Tauri
KW - techniques: image processing
KW - techniques: image processing: variables: T Tauri
UR - http://www.scopus.com/inward/record.url?scp=85069973666&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85069973666&partnerID=8YFLogxK
U2 - 10.3847/2041-8213/ab1b42
DO - 10.3847/2041-8213/ab1b42
M3 - Article
AN - SCOPUS:85069973666
SN - 2041-8205
VL - 877
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 1
M1 - L3
ER -