Sample and Statistical Analysis of the Near-Earth Object Wide-field Infrared Survey Explorer Variability of the 6.7 GHz Methanol Maser Sources

Song, Shi-Min; Chen, X.; Shen, Zhi-Qiang; Wang, Y. X.; Yang, Ke‐Fang; Miao, Dan; Wu, Jiong-Heng; Liu, Junting; Zhang, Yan-Kun

doi:10.3847/1538-4365/acb04c

Cited by 3 publications

(8 citation statements)

References 99 publications

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“…Appendix Table A3 provides the fitting results and additional information relative to these sources. The extracted temperatures range from 430 to 1100 K with an average value of 840 K. Given such high temperatures, we suggest that these sources are probably premain-sequence (PMS) stars, albeit our current study cannot completely rule out the possibility that some of them are evolved stars (e.g., AGB stars; Chen et al 2013) (Mei et al 2023), and high-mass YSOs associated with 6.7 GHz methanol masers (Song et al 2023). In most cases, the variability behaviors of these YSOs is considered to be caused by their intrinsic nature in the PMS phase.…”

Section: Periodic Variable Sources Surrounding G24mentioning

confidence: 76%

Luminosity Outburst of a High-mass Young Stellar Object Triggered by the Surrounding Radiation Field

Liu

Chen

et al. 2023

ApJL

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We present observations of the 6.7 GHz methanol and 4.8 GHz formaldehyde masers toward the high-mass young stellar object G24.33+0.14 (hereafter G24). Our observations were conducted from 2019 to 2021 using the Shanghai Tianma 65 m Radio Telescope and the Very Large Array in response to the luminosity outburst event traced by these two species masers in 2019. Our results indicate that the provenance of the maser flares is unlikely to be ascribed to the protostar of G24 itself. Through analyzing NEOWISE infrared monitoring data, we identified two light curves of G24 with long-term (3083 days, ∼8.5 yr) and short-term (424 days) periods. Intriguingly, 11 periodic variable sources located in the same bubble as G24 exhibiting periods comparable to the short-term period of G24 were also detected. The analysis of the spectral energy distributions of these periodic variables revealed a possible correlation between their temperature fluctuations and the surrounding radiation field that possibly emanates from the driving source of the bubble. This source could be an individual supergiant protostar of a few hundred solar masses with periodic pulsation potentially accounting for the observed short-term period in the G24 region.

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Section: Periodic Variable Sources Surrounding G24mentioning

confidence: 76%

Luminosity Outburst of a High-mass Young Stellar Object Triggered by the Surrounding Radiation Field

Liu

Chen

et al. 2023

ApJL

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“…With reference to Park et al (2021), Mei et al (2023), andSong et al (2023), the light curves of the identified variables are classified into two categories: secular and stochastic. The secular category includes linear, sin, and sin+linear, while the stochastic category includes burst, drop, and irregular.…”

Section: Variability Classificationmentioning

confidence: 99%

“…The secular category includes linear, sin, and sin+linear, while the stochastic category includes burst, drop, and irregular. In a method similar to Mei et al (2023) and Song et al (2023), we used Python package scipy.optimize.curve_fit (Virtanen et al 2020) to fit the light curve, and prioritize simple models to classify the variable sources as linear, sin, sin+linear, and stochastic in order based on goodness (R 2 ) of fit. The detailed fitted parameters of all types of variables are listed in Tables B1 and B2 in Appendix B, and Table B3 gives parameters of nonvariables.…”

Section: Variability Classificationmentioning

confidence: 99%

“…It is important to pay attention to sudden bursts in relatively stable periodic variations, as they may be associated with special events, such as episodic accretion. We followed the approach of Mei et al (2023) and Song et al (2023), with an addition for selecting burst sources from secular variables. In addition to stochastic bursts, the criteria for bursts in Section 3.2.1 were applied to secular variables.…”

Section: Bursts In Secular and Stochastic Variablesmentioning

confidence: 99%

“…The internationally available and comprehensive mid-infrared variable database from the Near-Earth Object Wide-field Infrared Survey Explorer Reactivation Mission (NEOWISE) provides a great opportunity for conducting effective infrared variability research (Mainzer et al 2011(Mainzer et al , 2014. Currently, only a few studies have been conducted on low-mass YSOs, intermediate-mass YSOs, and high-mass YSOs associated with a methanol maser (Park et al 2021;Mei et al 2023;Song et al 2023). There is still a lack of systematic study on the variability of high-mass YSOs for large samples.…”

Section: Introductionmentioning

confidence: 99%

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Sample and Statistical Analysis on NEOWISE Variability of ATLASGAL Sources

Lu,

Chen,

Song

et al. 2024

ApJS

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This study focuses on the analysis of mid-infrared variability in a sample of high-mass young stellar objects (YSOs) associated with the cataloged sources from the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL). The Near-Earth Object Wide-field Infrared Survey Explorer Reactivation Mission (NEOWISE) database was used to explore the long-term mid-infrared variability of these high-mass YSOs at a half-year scale. After matching with NEOWISE photometric measurements, a total of 2230 ATLASGAL sources were selected for the variability analysis, out of which 717 were identified as variables. The derived proportions of variables at different evolutionary stages show that the variability rate of high-mass YSOs is highest during the YSO stage and decreases with evolution toward the H ii region stage, resembling the behavior of low-mass YSOs. The variables can be classified into six types based on their light curves, divided into two categories: secular (linear, sin, sin+linear) and stochastic variables (burst, drop, and irregular). The magnitude–color variations observed in ∼160 secular variables can be mainly divided into “bluer when brighter/redder when dimming” and “redder when brighter/bluer when dimming,” likely originating from changes in accretion rate or the effect of extinction due to obscuration. Moreover, several episodic accretion candidates were selected for further observational studies.

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The accretion burst of the massive young stellar object G323.46−0.08

Wolf,

Stecklum,

Caratti o Garatti

et al. 2024

A&A

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Accretion bursts from low-mass young stellar objects (YSOs) have been known for many decades. In recent years, the first accretion bursts of massive YSOs (MYSOs) have been observed. These phases of intense protostellar growth are of particular importance for studying massive star formation. Bursts of MYSOs are accompanied by flares of Class II methanol masers (hereafter masers), which are caused by an increase in exciting mid-infrared (MIR) emission. They can lead to long-lasting thermal afterglows of the dust continuum radiation visible at infrared (IR) and (sub)millimeter (hereafter (sub)mm) wavelengths. Furthermore, they might cause a scattered light echo. The G323.46$-$0.08 (hereafter G323) event, which shows all these features, extends the small sample of known MYSO bursts. Maser observations of the MYSO G323 show evidence of a flare, which was presumed to be caused by an accretion burst. This should be verified with IR data. We used time-dependent radiative transfer (TDRT) to characterize the heating and cooling timescales for eruptive MYSOs and to infer the main burst parameters. Burst light curves, as well as the pre-burst spectral energy distribution (SED) were established from archival IR data. The properties of the MYSO, including its circumstellar disk and envelope, were derived by using static radiative transfer modeling of pre-burst data. For the first time, TDRT was used to predict the temporal evolution of the SED. Observations with SOFIA/HAWC+ were performed to constrain the burst energy from the strength of the thermal afterglow. Image subtraction and ratioing were applied to reveal the light echo. The G323 accretion burst is confirmed. It reached its peak in late 2013/early 2014 with a $K_ s $-band increase of $ sim ts ts mag. Both $K_ s $-band and integrated maser flux densities follow an exponential decay. TDRT indicates that the duration of the thermal afterglow in the far-infrared (FIR) can exceed the burst duration by years. The latter was proved by SOFIA observations, which indicate a flux increase of $(14.2 at $70\ m$ and $(8.5 at ts in 2022 (2 years after the burst ended). A one-sided light echo emerged that was propagating into the interstellar medium. The burst origin of the G323 maser flare has been verified. TDRT simulations revealed the strong influence of the burst energetics and the local dust distribution on the strength and duration of the afterglow. The G323 burst is probably the most energetic MYSO burst that has been observed so far. Within $8.4 \, yrs$, an energy of $(0.9 erg$ was released. The short timescale points to the accretion of a compact body, while the burst energy corresponds to an accumulated mass of at least $(7 Jup $ and possibly even more if the protostar is bloated. In this case, the accretion event might have triggered protostellar pulsations, which give rise to the observed maser periodicity. The associated IR light echo is the second observed from a MYSO burst.

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Sample and Statistical Analysis of the Near-Earth Object Wide-field Infrared Survey Explorer Variability of the 6.7 GHz Methanol Maser Sources

Cited by 3 publications

References 99 publications

Luminosity Outburst of a High-mass Young Stellar Object Triggered by the Surrounding Radiation Field

Luminosity Outburst of a High-mass Young Stellar Object Triggered by the Surrounding Radiation Field

Sample and Statistical Analysis on NEOWISE Variability of ATLASGAL Sources

The accretion burst of the massive young stellar object G323.46−0.08

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