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2 results on '"FIELD-IMAGING FAR-INFRARED LINE SPECTROMETERS"'

1. Infrared observations of the flaring maser source G358.93-0.03: SOFIA confirms an accretion burst from a massive young stellar object

Author

Stecklum, B., Wolf, V., Linz, H., Caratti, O, Garatti, A., Schmidl, S., Klose, S., Eislöffel, J., Fischer, C., Brogan, C., Burns, R. A., Bayandina, O., Cyganowski, C., Gurwell, M., Hunter, T., Hirano, N., Kim, K. -T., MacLeod, G. C., Menten, K. M., Olech, M., Orosz, G., Sobolev, A., Sridharan, T. K., Surcis, G., Sugiyama, K., Van, Der, Walt, J., Volvach, A., Yonekura, Y., Stecklum, B., Wolf, V., Linz, H., Caratti, O, Garatti, A., Schmidl, S., Klose, S., Eislöffel, J., Fischer, C., Brogan, C., Burns, R. A., Bayandina, O., Cyganowski, C., Gurwell, M., Hunter, T., Hirano, N., Kim, K. -T., MacLeod, G. C., Menten, K. M., Olech, M., Orosz, G., Sobolev, A., Sridharan, T. K., Surcis, G., Sugiyama, K., Van, Der, Walt, J., Volvach, A., and Yonekura, Y.

Abstract

Context. Class II methanol masers are signposts of massive young stellar objects (MYSOs). Recent evidence shows that flares of these masers are driven by MYSO accretion bursts. Thus, maser monitoring can be used to identify such bursts which are hard to discover otherwise. Infrared observations reveal burst-induced changes in the spectral energy distribution (first and foremost a luminosity increase), which provide valuable information on a very intense phase of high-mass star formation. Aims. In mid-January 2019, flaring of the 6.7 GHz CH3OH maser (hereafter maser) of the MYSO G358.93-0.03 (hereafter G358) was reported. The international maser community initiated an extensive observational campaign which revealed extraordinary maser activity and yielded the detection of numerous new masering transitions. Interferometric imaging with the Atacama Large Millimeter/submillimeter Array and the Submillimeter Array resolved the maser emitting core of the star forming region and proved the association of the masers with the brightest continuum source (MM1), which hosts a hot molecular core. These observations, however, failed to detect a significant rise in the (sub)millimeter dust continuum emission. Therefore, we performed near-infrared (NIR) and far-infrared (FIR) observations to prove or disprove whether the CH3OH flare was driven by an accretion burst. Methods. NIR imaging with the Gamma-Ray Burst Optical/Near-infrared Detector has been acquired and integral-field spectroscopy with the Field-Imaging Far-Infrared Line Spectrometer (FIFI-LS) aboard the Stratospheric Observatory for Infrared Astronomy (SOFIA) was carried out on two occasions to detect possible counterparts to the (sub)millimeter sources and compare their photometry to archival measurements. The comparison of pre-burst and burst spectral energy distributions is of crucial importance to judge whether a substantial luminosity increase, caused by an accretion burst, is present and if it triggered the maser f

Published
2021

2. Infrared observations of the flaring maser source G358.93-0.03: SOFIA confirms an accretion burst from a massive young stellar object

Author

Mark Gurwell, Hendrik Linz, J.L. Van der Walt, Claudia Cyganowski, C. Fischer, A. E. Volvach, Gabriele Surcis, Ross A. Burns, Andrej M. Sobolev, V. Wolf, J. Eislöffel, Sylvio Klose, O. Bayandina, Bringfried Stecklum, Crystal L. Brogan, Koichiro Sugiyama, A. Caratti o Garatti, G. C. MacLeod, Gabor Orosz, Yoshinori Yonekura, Kee-Tae Kim, S. Schmidl, Naomi Hirano, Karl M. Menten, M. Olech, Todd R. Hunter, T. K. Sridharan, ITA, USA, GBR, DEU, CAN, TWN, KOR, JPN, IRL, NLD, POL, CHN, ZAF, RUS, and University of St Andrews. School of Physics and Astronomy

Subjects
GAMMA RAYS, SPECTROMETERS, Young stellar object, DUST, Astrophysics, RADIATIVE TRANSFER, ENVIRONMENTAL CHARACTERISTIC, 01 natural sciences, INTERFEROMETRIC IMAGING, RADIATIVE TRANSFER MODEL, law.invention, Luminosity, law, QB Astronomy, Astrophysics::Solar and Stellar Astrophysics, Maser, FIR FILTERS, 010303 astronomy & astrophysics, QC, QB, Physics, SPECTROSCOPY, 3rd-DAS, ATACAMA LARGE MILLIMETER/SUB-MILLIMETER ARRAYS, FIELD-IMAGING FAR-INFRARED LINE SPECTROMETERS, LUMINANCE, Astrophysics - Solar and Stellar Astrophysics, SPECTRAL ENERGY DISTRIBUTION, Spectral energy distribution, METHANOL, Astrophysics::Earth and Planetary Astrophysics, Flare, ACCRETION, ACCRETION DISKS, INFRARED DEVICES, INDIVIDUAL: G358.93-0.03 [STARS], Astrophysics::High Energy Astrophysical Phenomena, MASERS, FOS: Physical sciences, Context (language use), Astrophysics::Cosmology and Extragalactic Astrophysics, Submillimeter Array, indvididual objects (G358.93-0.03) [Stars], FORMATION [STARS], 0103 physical sciences, INTEGRAL FIELD SPECTROSCOPY, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, PROTOSTARS [STARS], STRATOSPHERIC OBSERVATORY FOR INFRARED ASTRONOMIES, 010308 nuclear & particles physics, Astronomy and Astrophysics, GIANT STARS, Accretion (astrophysics), QC Physics, 13. Climate action, Space and Planetary Science
Abstract

Class II methanol masers are signs of massive young stellar objects (MYSOs). Recent findings show that MYSO accretion bursts cause flares of these masers. Thus, maser monitoring can be used to identify such bursts. Burst-induced SED changes provide valuable information on a very intense phase of high-mass star formation. In mid-January 2019, a maser flare of the MYSO G358.93-0.03 was reported. ALMA and SMA imaging resolved the core of the star forming region and proved the association of the masers with the brightest continuum source MM1. However, no significant flux rise of the (sub)mm dust continuum was found. Thus, we performed NIR imaging with GROND and IFU spectroscopy with FIFI-LS aboard SOFIA to detect possible counterparts to the (sub)mm sources, and compare their photometry to archival measurements. The comparison of pre-burst and burst SEDs is of crucial importance to judge whether a luminosity increase due to the burst is present and if it triggered the maser flare. The FIR fluxes of MM1 measured with FIFI-LS exceed those from Herschel significantly, which clearly confirms the presence of an accretion burst. The second epoch data, taken about 16 months later, still show increased fluxes. Our RT modeling yielded major burst parameters and suggests that the MYSO features a circumstellar disk which might be transient. From the multi-epoch SEDs, conclusions on heating and cooling time-scales could be drawn. Circumstances of the burst-induced maser relocation have been explored. The verification of the accretion burst from G358 is another confirmation that Class II methanol maser flares represent an alert for such events. The few events known to date already indicate that there is a broad range in burst strength and duration as well as environmental characteristics. The G358 event is the shortest and least luminous MYSO accretion burst so far., Comment: 22 pages, 11 figures, accepted by A&A. Abstract abridged for arxiv submission

Published
2021

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