TY - JOUR

T1 - Millimeter methanol emission in the high-mass young stellar object G24.33+0.14

AU - Hirota, Tomoya

AU - Wolak, Pawel

AU - Hunter, Todd R.

AU - Brogan, Crystal L.

AU - Bartkiewicz, Anna

AU - Durjasz, Michal

AU - Kobak, Agnieszka

AU - Olech, Mateusz

AU - Szymczak, Marian

AU - Burns, Ross A.

AU - Aberfelds, Artis

AU - Baek, Giseon

AU - Brand, Jan

AU - Breen, Shari

AU - Byun, Do-young

AU - Caratti O Garatti, Alessio

AU - Chen, Xi

AU - Chibueze, James O

AU - Cyganowski, Claudia

AU - Eislöffel, Jochen

AU - Ellingsen, Simon

AU - Hirano, Naomi

AU - Hu, Bo

AU - Kang, Ji-hyun

AU - Kim, Jeong-sook

AU - Kim, Jungha

AU - Kim, Kee-tae

AU - Kim, Mi Kyoung

AU - Kramer, Busaba

AU - Lee, Jeong-eun

AU - Linz, Hendrik

AU - Liu, Tie

AU - Macleod, Gordon

AU - Mccarthy, Tiege P

AU - Menten, Karl

AU - Motogi, Kazuhito

AU - Oh, Chung-sik

AU - Orosz, Gabor

AU - Sobolev, Andrey M.

AU - Stecklum, Bringfried

AU - Sugiyama, Koichiro

AU - Sunada, Kazuyoshi

AU - Uscanga, Lucero

AU - Van Den Heever, Fanie

AU - Volvach, Alexandr E.

AU - Volvach, Larisa N.

AU - Wu, Yuan Wei

AU - Yonekura, Yoshinori

N1 - We thank the anonymous referee for a helpful review, which has improved the manuscript. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2015.1.01571.S and 2018.A.00068.T. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan), together with NRC (Canada), NSC and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. This publication makes use of data products from the Wide-field Infrared Survey Explorer (WISE), which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. This publication also makes use of data products from NEOWISE, which is a project of the Jet Propulsion Laboratory/California Institute of Technology, funded by the Planetary Science Division of the National Aeronautics and Space Administration. TH is financially supported by the MEXT/JSPS KAKENHI Grant Numbers 17K05398, 18H05222, and 20H05845. MO is supported by Ministry of Education and Science of the Republic of Poland as part of support and granting funds for the Polish contribution to the International LOFAR Telescope (arrangement no. 2021/WK/02) and maintenance of the LOFAR PL-612 Baldy (MSHE decision no. 59/E-383/SPUB/SP/2019.1). RAB is supported by East Asia Core Observatory Association (EACOA) as an EACOA fellowship. ACG has been supported by PRIN-INAF-MAIN-STREAM 2017 “Protoplanetary disks seen through the eyes of new-generation instruments” and by PRIN-INAF 2019 “Spectroscopically tracing the disk dispersal evolution (STRADE)”. JSK has been supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2016R1A5A1013277 and 2020R1A2C1007219). AMS was supported by the Large Scientific Project of the Russian Ministry of Science and Higher Education ‘Theoretical and experimental studies of the formation and evolution of extrasolar planetary systems and characteristics of exoplanets’ (No. 075-15-2020-780, contract 780-10). LU acknowledges support from the University of Guanajuato (Mexico) grant ID CIIC 164/2022. AV and LV are supported by Ministry of Science and Higher Education of the Russian Federation Grant 075-15-2020-780. Data analyses were in part carried out on common use data analysis computer system at the Astronomy Data Center, ADC, of the National Astronomical Observatory of Japan.

PY - 2022/10/3

Y1 - 2022/10/3

N2 - In 2019 September, a sudden flare of the 6.7 GHz methanol maser was observed toward the high-mass young stellar object (HMYSO) G24.33+0.14. This may represent the fourth detection of a transient mass accretion event in an HMYSO after 5255IR NIRS3, NGC 63341-MM1, and G358.93-0.03-MM1. G24.33+0.14 is unique among these sources as it clearly shows a repeating flare with an 8yr interval. Using the Atacama Large Millimeter/submillimeter Array (ALMA), we observed the millimeter continuum and molecular lines toward G24.33+0.14 in the pre-flare phase in 2016 August (ALMA Cycle 3) and the mid-flare phase in 2019 September (ALMA Cycle 6). We identified three continuum sources in G24.33+0.14, and the brightest source, C1, which is closely associated with the 6.7 GHz maser emission, shows only a marginal increase in flux density with a flux ratio (Cycle 6/Cycle 3) of 1.16 +/- 0.01, considering an additional absolute flux calibration uncertainty of 10%. We identified 26 transitions from 13 molecular species other than methanol, and they exhibit similar levels of flux differences with an average flux ratio of 1.12 +/- 0.15. In contrast, eight methanol lines observed in Cycle 6 are brighter than those in Cycle 3 with an average flux ratio of 1.23 +/- 0.13, and the higher excitation lines tend to show a larger flux increase. If this systematic increasing trend is real, it would suggest radiative heating close to the central HMYSO due to an accretion event which could expand the size of the emission region and/or change the excitation conditions. Given the low brightness temperatures and small flux changes, most of the methanol emission is likely to be predominantly thermal, except for the 229.759 GHz (8(-1)-7(0) E) line known as a class 1 methanol maser. The flux change in the millimeter continuum of G24.33+0.14 is smaller than in S255IR NIRS3 and NGC 63341-MM1 but is comparable with that in G358.93-0.03-MM1, suggesting different amounts of accreted mass in these events.

AB - In 2019 September, a sudden flare of the 6.7 GHz methanol maser was observed toward the high-mass young stellar object (HMYSO) G24.33+0.14. This may represent the fourth detection of a transient mass accretion event in an HMYSO after 5255IR NIRS3, NGC 63341-MM1, and G358.93-0.03-MM1. G24.33+0.14 is unique among these sources as it clearly shows a repeating flare with an 8yr interval. Using the Atacama Large Millimeter/submillimeter Array (ALMA), we observed the millimeter continuum and molecular lines toward G24.33+0.14 in the pre-flare phase in 2016 August (ALMA Cycle 3) and the mid-flare phase in 2019 September (ALMA Cycle 6). We identified three continuum sources in G24.33+0.14, and the brightest source, C1, which is closely associated with the 6.7 GHz maser emission, shows only a marginal increase in flux density with a flux ratio (Cycle 6/Cycle 3) of 1.16 +/- 0.01, considering an additional absolute flux calibration uncertainty of 10%. We identified 26 transitions from 13 molecular species other than methanol, and they exhibit similar levels of flux differences with an average flux ratio of 1.12 +/- 0.15. In contrast, eight methanol lines observed in Cycle 6 are brighter than those in Cycle 3 with an average flux ratio of 1.23 +/- 0.13, and the higher excitation lines tend to show a larger flux increase. If this systematic increasing trend is real, it would suggest radiative heating close to the central HMYSO due to an accretion event which could expand the size of the emission region and/or change the excitation conditions. Given the low brightness temperatures and small flux changes, most of the methanol emission is likely to be predominantly thermal, except for the 229.759 GHz (8(-1)-7(0) E) line known as a class 1 methanol maser. The flux change in the millimeter continuum of G24.33+0.14 is smaller than in S255IR NIRS3 and NGC 63341-MM1 but is comparable with that in G358.93-0.03-MM1, suggesting different amounts of accreted mass in these events.

UR - https://www.webofscience.com/wos/woscc/full-record/WOS:000849847000001

UR - http://www.scopus.com/inward/record.url?scp=85140422833&partnerID=8YFLogxK

U2 - 10.1093/pasj/psac067

DO - 10.1093/pasj/psac067

M3 - Article

VL - 74

SP - 1234

EP - 1262

JO - Publications of the Astronomical Society of Japan

JF - Publications of the Astronomical Society of Japan

SN - 0004-6264

IS - 5

ER -