Circumstellar disks revealed byH/Kflux variation gradients
| العنوان: | Circumstellar disks revealed byH/Kflux variation gradients |
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| المؤلفون: | M. Haas, Rolf Chini, C. Westhues, F. Pozo Nuñez, Michael Ramolla, Klaus W. Hodapp |
| المصدر: | Astronomy & Astrophysics. 578:A98 |
| بيانات النشر: | EDP Sciences, 2015. |
| سنة النشر: | 2015 |
| مصطلحات موضوعية: | Physics, Brightness, Young stellar object, FOS: Physical sciences, Flux, Astronomy and Astrophysics, Astrophysics, Color temperature, Wavelength, Amplitude, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Magnitude (astronomy), Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Halo, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics |
| الوصف: | The variability of young stellar objects (YSO) changes their brightness and color preventing a proper classification in traditional color-color and color magnitude diagrams. We have explored the feasibility of the flux variation gradient (FVG) method for YSOs, using $H$ and $K$ band monitoring data of the star forming region RCW\,38 obtained at the University Observatory Bochum in Chile. Simultaneous multi-epoch flux measurements follow a linear relation $F_{H}=\alpha + \beta \cdot F_{K}$ for almost all YSOs with large variability amplitude. The slope $\beta$ gives the mean $HK$ color temperature $T_{var}$ of the varying component. Because $T_{var}$ is hotter than the dust sublimation temperature, we have tentatively assigned it to stellar variations. If the gradient does not meet the origin of the flux-flux diagram, an additional non- or less-varying component may be required. If the variability amplitude is larger at the shorter wavelength, e.g. $\alpha < 0$, this component is cooler than the star (e.g. a circumstellar disk); vice versa, if $\alpha > 0$, the component is hotter like a scattering halo or even a companion star. We here present examples of two YSOs, where the $HK$ FVG implies the presence of a circumstellar disk; this finding is consistent with additional data at $J$ and $L$. One YSO shows a clear $K$-band excess in the $JHK$ color-color diagram, while the significance of a $K$-excess in the other YSO depends on the measurement epoch. Disentangling the contributions of star and disk it turns out that the two YSOs have huge variability amplitudes ($\sim 3-5$\,mag). The $HK$ FVG analysis is a powerful complementary tool to analyze the varying components of YSOs and worth further exploration of monitoring data at other wavelengths. Comment: 5 pages, 5 figures, accepted for publication in Astronomy and Astrophysics |
| تدمد: | 1432-0746 0004-6361 |
| DOI: | 10.1051/0004-6361/201526107 |
| URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::ac3178b690c2dbef2b138c0ec574c54c https://doi.org/10.1051/0004-6361/201526107 |
| Rights: | OPEN |
| رقم الانضمام: | edsair.doi.dedup.....ac3178b690c2dbef2b138c0ec574c54c |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 14320746 00046361 |
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| DOI: | 10.1051/0004-6361/201526107 |