Nobeyama 45 m mapping observations toward Orion A. I. Molecular outflows

Abstract

We conducted an exploration of ${}^{12}$CO molecular outflows in the Orion A giant molecular cloud to investigate outflow feedback using ${}^{12}$CO ($J = 1\!-\!0$) and ${}^{13}$CO ($J = 1\!-\!0$) data obtained by the Nobeyama 45 m telescope. In the region excluding the center of OMC 1, we identified 44 ${}^{12}$CO (including 17 newly detected) outflows based on the unbiased and systematic procedure of automatically determining the velocity range of the outflows and separating the cloud and outflow components. The optical depth of the ${}^{12}$CO emission in the detected outflows is estimated to be approximately 5. The total momentum and energy of the outflows, corrected for optical depth, are estimated to be $1.6 \times 10^{2}\, M_{\odot }\:$km$\:$s$^{-1}$ and $1.5\times 10^{46}\:$erg, respectively. The momentum and energy ejection rate of the outflows are estimated to be 36% and 235% of the momentum and energy dissipation rates of the cloud turbulence, respectively. Furthermore, the ejection rates of the outflows are comparable to those of the expanding molecular shells estimated by Feddersen et al. (2018, ApJ, 862, 121). Cloud turbulence cannot be sustained by the outflows and shells unless the energy conversion efficiency is as high as 20%.

ORion Alma New GEneration Survey (ORANGES)

“…FIR1a-b, MMS5, SIMBA-a, and FIR6c-a are sources for which the two properties are clearly observed as an outflow was detected towards these sources in previous studies (e.g. Aso et al 2000;Williams et al 2003;Takahashi et al 2008;Tobin et al 2016;Tanabe et al 2019;Feddersen et al 2020;Nagy et al 2020). A large outflow was also detected towards the MMS9 and CSO33 systems, but the angular resolution does not allow us to determine which of the components is actually the driving source (e.g.…”

“…A large outflow was also detected towards the MMS9 and CSO33 systems, but the angular resolution does not allow us to determine which of the components is actually the driving source (e.g. Williams et al 2003;Takahashi et al 2008;Tanabe et al 2019;Feddersen et al 2020).…”

“…An outflow has been detected towards the MMS2 system (e.g. Aso et al 2000;Williams et al 2003;Takahashi et al 2008;Tanabe et al 2019;Feddersen et al 2020), but we need high angular resolution studies to understand which of the two sources is the driving source, and thus which of the two sources is younger. Finally, in the case of CSO3-b, we can see that the 32.9 GHz emission is quite weak, but we cannot determine whether free-free emission is present.…”

“…Outflows have been detected towards CSO33 and MMS9, but the angular resolution of the observations was insufficient to determine which of the sources actually drives them (e.g. Williams et al 2003;Takahashi et al 2008;Tanabe et al 2019;Feddersen et al 2020). The dust emissivity spectral indexes of these sources are very different, with β ≤ 0.7 for CSO33-a, β = 0 for MMS9-b, and β ∈ [0.3;1.8] for MMS9-c.…”

A Census of Protostellar Outflows in Nearby Molecular Clouds

“…velocity components in blue and red contours, which are considered to be outflows by Tanabe et al (2019). The mass of these high-velocity components is 268 M .…”