论文标题

限制0类Protostar Hops 383的化学特征和爆发机制

Constraining the Chemical Signatures and the Outburst Mechanism of the Class 0 Protostar HOPS 383

论文作者

Sharma, Rajeeb, Tobin, John J., Sheehan, Patrick D., Megeath, S. Thomas, Fischer, William J., Jorgensen, Jes K., Safron, Emily J., Nagy, ZSofia

论文摘要

我们提出了朝向啤酒花383的观察结果,这是使用Alma,VLA和SMA位于Orion Molecular Cloud内的第一个已知的爆发类别0 Protostar。 SMA观察结果揭示了围绕HOPS 383的包膜量表连续体和分子线发射,在0.85 mm,1.1 mm和1.3 mm处。这些图像显示Hco $^+$和H $^{13} $ CO $^+$在连续体上或附近峰值,而N $ _2 $ H $^+$在同一位置减少了。这反映了基本的化学反应,在形成hco $^+$的同时,在原始批准的情况下蒸发掉了n $ _2 $ h $^+$。我们还观察到由$^{12} $ co($ j = 2 \ rightarrow 1 $)和($ j = 3 \ rightarrow 2 $)所追踪的分子流出。在ALMA 0.87毫米尘埃连续体中解决了一个磁盘,与流出方向正交,明显半径为$ \ sim $ 62 au。当适合ALMA可见性时,连续体的辐射传输建模可使磁盘质量为0.02 m $ _ {\ odot} $。包括VLA 8毫米数据在内的模型表明,由于较长的波长粉尘不透明度,磁盘质量可能会较大10倍。磁盘温度和表面密度曲线来自建模,假定的原始质量为0.5 m $ _ {\ odot} $表明,爆发前的Toomre $ Q $参数$ <1 $ <1 $ <1 $,使得引力不稳定是在磁盘足够早的时间早期解释Outbursts的可行机制。

We present observations toward HOPS 383, the first known outbursting Class 0 protostar located within the Orion molecular cloud using ALMA, VLA, and SMA. The SMA observations reveal envelope scale continuum and molecular line emission surrounding HOPS 383 at 0.85 mm, 1.1 mm, and 1.3 mm. The images show that HCO$^+$ and H$^{13}$CO$^+$ peaks on or near the continuum, while N$_2$H$^+$ is reduced at the same position. This reflects the underlying chemistry where CO evaporating close to the protostar destroys N$_2$H$^+$ while forming HCO$^+$. We also observe the molecular outflow traced by $^{12}$CO ($J = 2 \rightarrow 1$) and ($J = 3 \rightarrow 2$). A disk is resolved in the ALMA 0.87 mm dust continuum, orthogonal to the outflow direction, with an apparent radius of $\sim$62 AU. Radiative transfer modeling of the continuum gives disk masses of 0.02 M$_{\odot}$ when fit to the ALMA visibilities. The models including VLA 8 mm data indicate that the disk mass could be up to a factor of 10 larger due to lower dust opacity at longer wavelengths. The disk temperature and surface density profiles from the modeling, and an assumed protostar mass of 0.5 M$_{\odot}$ suggest that the Toomre $Q$ parameter $< 1$ before the outburst, making gravitational instability a viable mechanism to explain outbursts at an early age if the disk is sufficiently massive.

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