The candidates of long-periodic variable sources in 6.7 GHz methanol masers associated with four high-mass star-forming regions
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| Format: | Preprint |
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2024
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| _version_ | 1866916141000032256 |
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| author | Tanabe, Yoshihiro Yonekura, Yoshinori |
| author_facet | Tanabe, Yoshihiro Yonekura, Yoshinori |
| contents | Results of the long-term monitoring observations of the 6.7 GHz Class II methanol masers associated with the four high-mass star-forming regions by Hitachi 32-m radio telescope are presented. We detected periodic flux variability in G06.795-0.257, G10.472+0.027, G12.209-0.102, and G13.657-0.599 with the periods of 968, 1624, 1272, and 1266 d, respectively, although the detected period is tentative due to the short monitoring term relative to the estimated period. The facts that the flux variation patterns show the symmetric sine curves and that the luminosities of the central protostar and periods of maser flux variation are consistent with the expected period-luminosity (PL) relation suggest that the mechanisms of maser flux variability of G10.472+0.027 and G12.209-0.102 can be explained by protostellar pulsation instability. From the PL relation, central stars of these two sources are expected to be very high-mass protostars with a mass of 40 M and to have the mass accretion rate of 2*10-2 M yr-1. On the other hand, G06.795-0.257 and G13.657-0.599 have the intermittent variation patterns and have luminosities that are an order of magnitude smaller than those expected from PL relation, suggesting variation mechanisms of these sources originated from binary system. Since almost all the maser features vary with the same period regardless of its geometry, periodic accretion model may be appropriate mechanisms for flux variability in G06.795-0.257 and G13.657-0.599. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2402_17314 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | The candidates of long-periodic variable sources in 6.7 GHz methanol masers associated with four high-mass star-forming regions Tanabe, Yoshihiro Yonekura, Yoshinori Astrophysics of Galaxies Results of the long-term monitoring observations of the 6.7 GHz Class II methanol masers associated with the four high-mass star-forming regions by Hitachi 32-m radio telescope are presented. We detected periodic flux variability in G06.795-0.257, G10.472+0.027, G12.209-0.102, and G13.657-0.599 with the periods of 968, 1624, 1272, and 1266 d, respectively, although the detected period is tentative due to the short monitoring term relative to the estimated period. The facts that the flux variation patterns show the symmetric sine curves and that the luminosities of the central protostar and periods of maser flux variation are consistent with the expected period-luminosity (PL) relation suggest that the mechanisms of maser flux variability of G10.472+0.027 and G12.209-0.102 can be explained by protostellar pulsation instability. From the PL relation, central stars of these two sources are expected to be very high-mass protostars with a mass of 40 M and to have the mass accretion rate of 2*10-2 M yr-1. On the other hand, G06.795-0.257 and G13.657-0.599 have the intermittent variation patterns and have luminosities that are an order of magnitude smaller than those expected from PL relation, suggesting variation mechanisms of these sources originated from binary system. Since almost all the maser features vary with the same period regardless of its geometry, periodic accretion model may be appropriate mechanisms for flux variability in G06.795-0.257 and G13.657-0.599. |
| title | The candidates of long-periodic variable sources in 6.7 GHz methanol masers associated with four high-mass star-forming regions |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2402.17314 |