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| Main Authors: | , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| Online Access: | https://arxiv.org/abs/2502.16749 |
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| _version_ | 1866916627191169024 |
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| author | Kalscheur, Matt France, Kevin Nisini, Brunella Schneider, P. Christian Alexander, Richard Eisloffel, Jochen Campbell-White, Justyn Shang, Hsien Gangi, Manuele Guo, Zhen Chang, Seok-Jun |
| author_facet | Kalscheur, Matt France, Kevin Nisini, Brunella Schneider, P. Christian Alexander, Richard Eisloffel, Jochen Campbell-White, Justyn Shang, Hsien Gangi, Manuele Guo, Zhen Chang, Seok-Jun |
| contents | We use FUV spectra of 36 T Tauri stars, predominately from $\textit{Hubble Space Telescope}$'s ULLYSES program, to examine the kinematic properties of fluorescent H$_2$ emission lines for evidence of disk outflows. Leveraging improvements to the $\textit{HST}$-COS wavelength solution, we co-add isolated lines within four fluorescent progressions ([$\textit{v'}$,$\textit{J'}$] = [1,4], [1,7], [0,2], and [3,16]) to improve signal-to-noise, and we fit each co-added line profile with one or two Gaussian components. Of the high S/N line profiles (S/N $\geq$ 12 at the peak of the profile), over half are best fit with a combination of a broad and narrow Gaussian component. For profiles of the [1,4] and [1,7] progressions, we find a systematic blue-shift of a few km s$^{-1}$ between the broad and narrow centroid velocities and stellar radial velocities. For the [0,2] progression, we find centroid velocities consistently blueshifted with respect to stellar radial velocities on the order of -5 km s$^{-1}$ for the single and narrow components, and -10 km s$^{-1}$ for the broad components. Overall, the blueshifts observed in our sample suggest that the molecular gas traces an outflow from a disk wind in some sources, and not solely disk gas in Keplerian rotation. The low-velocity systematic blue-shifts, and emitting radii as inferred from line FWHMs, observed in our sample are similar to those observed with optical [O I] surveys of T Tauri stars. We estimate H$_2$ mass-loss rates of 10$^{-9}$ to 10$^{-11}$ $M_{\odot}$ yr$^{-1}$, but incomplete knowledge of wind parameters limits comparisons to global models. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2502_16749 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Evidence of a Disk-wind Origin for Fluorescent H$_2$ in Classical T Tauri Stars Kalscheur, Matt France, Kevin Nisini, Brunella Schneider, P. Christian Alexander, Richard Eisloffel, Jochen Campbell-White, Justyn Shang, Hsien Gangi, Manuele Guo, Zhen Chang, Seok-Jun Solar and Stellar Astrophysics Earth and Planetary Astrophysics Astrophysics of Galaxies We use FUV spectra of 36 T Tauri stars, predominately from $\textit{Hubble Space Telescope}$'s ULLYSES program, to examine the kinematic properties of fluorescent H$_2$ emission lines for evidence of disk outflows. Leveraging improvements to the $\textit{HST}$-COS wavelength solution, we co-add isolated lines within four fluorescent progressions ([$\textit{v'}$,$\textit{J'}$] = [1,4], [1,7], [0,2], and [3,16]) to improve signal-to-noise, and we fit each co-added line profile with one or two Gaussian components. Of the high S/N line profiles (S/N $\geq$ 12 at the peak of the profile), over half are best fit with a combination of a broad and narrow Gaussian component. For profiles of the [1,4] and [1,7] progressions, we find a systematic blue-shift of a few km s$^{-1}$ between the broad and narrow centroid velocities and stellar radial velocities. For the [0,2] progression, we find centroid velocities consistently blueshifted with respect to stellar radial velocities on the order of -5 km s$^{-1}$ for the single and narrow components, and -10 km s$^{-1}$ for the broad components. Overall, the blueshifts observed in our sample suggest that the molecular gas traces an outflow from a disk wind in some sources, and not solely disk gas in Keplerian rotation. The low-velocity systematic blue-shifts, and emitting radii as inferred from line FWHMs, observed in our sample are similar to those observed with optical [O I] surveys of T Tauri stars. We estimate H$_2$ mass-loss rates of 10$^{-9}$ to 10$^{-11}$ $M_{\odot}$ yr$^{-1}$, but incomplete knowledge of wind parameters limits comparisons to global models. |
| title | Evidence of a Disk-wind Origin for Fluorescent H$_2$ in Classical T Tauri Stars |
| topic | Solar and Stellar Astrophysics Earth and Planetary Astrophysics Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2502.16749 |