_version_ 1866912544902348800
author Li, Jialin
Close, Laird M.
Long, Feng
Males, Jared R.
Haffert, Sebastiaan Y.
Weinberger, Alycia
Follette, Katherine
Andrews, Sean
Carpenter, John
Foster, Warren B.
Van Gorkom, Kyle
Hedglen, Alexander D.
Herczeg, Gregory J.
Johnson, Parker T.
Kautz, Maggie Y.
Kueny, Jay K.
Li, Rixin
Liberman, Joshua
Long, Joseph D.
Lumbres, Jennifer
Marino, Sebastian
Matr`a, Luca
McEwen, Eden A.
Guyon, Olivier
Pearce, Logan A.
Pérez, Laura M.
Pinilla, Paola
Schatz, Lauren
Shi, Yangfan
Twitchell, Katie
Wagner, Kevin
Wilner, David
Wu, Ya-Lin
Zhang, Shangjia
Zhu, Zhaohuan
author_facet Li, Jialin
Close, Laird M.
Long, Feng
Males, Jared R.
Haffert, Sebastiaan Y.
Weinberger, Alycia
Follette, Katherine
Andrews, Sean
Carpenter, John
Foster, Warren B.
Van Gorkom, Kyle
Hedglen, Alexander D.
Herczeg, Gregory J.
Johnson, Parker T.
Kautz, Maggie Y.
Kueny, Jay K.
Li, Rixin
Liberman, Joshua
Long, Joseph D.
Lumbres, Jennifer
Marino, Sebastian
Matr`a, Luca
McEwen, Eden A.
Guyon, Olivier
Pearce, Logan A.
Pérez, Laura M.
Pinilla, Paola
Schatz, Lauren
Shi, Yangfan
Twitchell, Katie
Wagner, Kevin
Wilner, David
Wu, Ya-Lin
Zhang, Shangjia
Zhu, Zhaohuan
contents 2MASS J16120668-3010270 (hereafter 2MJ1612) is a young M0 star that hosts a protoplanetary disk in the Upper Scorpious star-forming region. Recent ALMA observations of 2MJ1612 show a mildly inclined disk ($i$=37$^\circ$) with a large dust-depleted gap (R$_\text{cav}\approx$0.4" or 53 au). We present high-contrast H$α$ observations from MagAO-X on the 6.5m Magellan Telescope and new high resolution sub-mm dust continuum observations with ALMA of 2MJ1612. On both 2025 April 13 and 16, we recovered a point source with H$α$ excess with SNR $\gtrsim$5 within the disk gap in our MagAO-X Angular and Spectral Differential (ASDI) images at a separation of 141.96$\pm$2.10 mas (23.45$\pm$0.29 au deprojected) from the star and position angle (PA)= 159.00$\pm$0.55$^\circ$. Furthermore, this H$α$ source is within close proximity to a K band point source in SPHERE/IRDIS observation taken on 2023 July 21 \citep{sphere2025sub}. The astrometric offset between the K band and H$α$ source can be explained by orbital motion of a bound companion. Thus our observations can be best explained by the discovery of an accreting protoplanet, 2MJ1612 b, with an estimated mass of 4$M_\text{Jup}$ and H$α$ line flux ranging from (29.7 $\pm$7.5)$\times$10$^{-16}$ ergs/s/cm$^2$ to (8.2$\pm$3.4)$\times$10$^{-16}$ ergs/s/cm$^2$. 2MJ1612 b is likely the third example of an accreting H$α$ protoplanet responsible for carving the gap in its host disk, joining PDS 70b and c. Further study is necessary to confirm and characterize this protoplanet candidate and to identify any additional protoplanets that may also play a role in shaping the gap.
format Preprint
id arxiv_https___arxiv_org_abs_2508_11155
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Discovery of H$α$ Emission from a Protoplanet Candidate Around the Young Star 2MASS J16120668-3010270 with MagAO-X
Li, Jialin
Close, Laird M.
Long, Feng
Males, Jared R.
Haffert, Sebastiaan Y.
Weinberger, Alycia
Follette, Katherine
Andrews, Sean
Carpenter, John
Foster, Warren B.
Van Gorkom, Kyle
Hedglen, Alexander D.
Herczeg, Gregory J.
Johnson, Parker T.
Kautz, Maggie Y.
Kueny, Jay K.
Li, Rixin
Liberman, Joshua
Long, Joseph D.
Lumbres, Jennifer
Marino, Sebastian
Matr`a, Luca
McEwen, Eden A.
Guyon, Olivier
Pearce, Logan A.
Pérez, Laura M.
Pinilla, Paola
Schatz, Lauren
Shi, Yangfan
Twitchell, Katie
Wagner, Kevin
Wilner, David
Wu, Ya-Lin
Zhang, Shangjia
Zhu, Zhaohuan
Earth and Planetary Astrophysics
2MASS J16120668-3010270 (hereafter 2MJ1612) is a young M0 star that hosts a protoplanetary disk in the Upper Scorpious star-forming region. Recent ALMA observations of 2MJ1612 show a mildly inclined disk ($i$=37$^\circ$) with a large dust-depleted gap (R$_\text{cav}\approx$0.4" or 53 au). We present high-contrast H$α$ observations from MagAO-X on the 6.5m Magellan Telescope and new high resolution sub-mm dust continuum observations with ALMA of 2MJ1612. On both 2025 April 13 and 16, we recovered a point source with H$α$ excess with SNR $\gtrsim$5 within the disk gap in our MagAO-X Angular and Spectral Differential (ASDI) images at a separation of 141.96$\pm$2.10 mas (23.45$\pm$0.29 au deprojected) from the star and position angle (PA)= 159.00$\pm$0.55$^\circ$. Furthermore, this H$α$ source is within close proximity to a K band point source in SPHERE/IRDIS observation taken on 2023 July 21 \citep{sphere2025sub}. The astrometric offset between the K band and H$α$ source can be explained by orbital motion of a bound companion. Thus our observations can be best explained by the discovery of an accreting protoplanet, 2MJ1612 b, with an estimated mass of 4$M_\text{Jup}$ and H$α$ line flux ranging from (29.7 $\pm$7.5)$\times$10$^{-16}$ ergs/s/cm$^2$ to (8.2$\pm$3.4)$\times$10$^{-16}$ ergs/s/cm$^2$. 2MJ1612 b is likely the third example of an accreting H$α$ protoplanet responsible for carving the gap in its host disk, joining PDS 70b and c. Further study is necessary to confirm and characterize this protoplanet candidate and to identify any additional protoplanets that may also play a role in shaping the gap.
title Discovery of H$α$ Emission from a Protoplanet Candidate Around the Young Star 2MASS J16120668-3010270 with MagAO-X
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2508.11155