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MINDS. A multi-instrument investigation into the molecule-rich JWST-MIRI spectrum of the DF Tau binary system

By Keith Cowing
Status Report
June 17, 2024
Filed under , , , , , , , , , , , ,
MINDS. A multi-instrument investigation into the molecule-rich JWST-MIRI spectrum of the DF Tau binary system
The JWST-MIRI MRS spectrum for DF Tau. Note the line forest present in the spectrum, which has a very high line-to-continuum ratio. — astro-ph.EP

Most stars form in multiple systems whose properties can significantly impact circumstellar disk evolution. We investigate the physical and chemical properties of the equal-mass, small separation (~66 mas, ~9 au) DF Tau binary system.

Previous observations indicated that only DF Tau A has a circumstellar disk. We present JWST-MIRI MRS observations of DF Tau. The MIRI spectrum shows a forest of H2O lines and emission from CO, C2H2, HCN, CO2, and OH. LTE slab models are used to determine the properties of the gas, and we analyze high angular spatial and spectral resolution data from ALMA, VLTI-GRAVITY, and IRTF-iSHELL to aid in the interpretation of the JWST data.

The 1.3 mm ALMA continuum data show two equal-brightness sources of compact (R<3 au) emission, with separations and movement consistent with astrometry from VLTI-GRAVITY and the known orbit. This is interpreted as a robust detection of a disk around DF Tau B, which we suggest may host a small (~1 au) cavity to reconcile all observations. The disk around DF Tau A is expected to be a full disk, and spatially and spectrally resolved dust and gas emission points to hot, close-in (<0.2 au) material.

Hot (~500-1000 K) H2O, HCN, and C2H2 emission in the MIRI data likely originate in the DF Tau A disk, while a cold (<200 K) H2O component with an extended emitting area is consistent with an origin from both disks. Despite the very compact outer disks, the inner disk composition and conditions are similar to isolated systems, suggesting that the close binary nature is not a driving factor in setting the inner disk chemistry.

However, constraining the geometry of the disks, for instance, via higher resolution ALMA observations, would provide additional insight into the mid-infrared gas emission. JWST observations of spatially resolved binaries will be important for understanding the impact of binarity on inner disk chemistry more generally.

Astrometric measurements of DF Tau B relative to DF Tau A (+ symbol). The best orbit of DF Tau B from Allen et al. (2017) is shown with a grey dashed line, while the data points used to fit that orbit are shown with grey stars. The measured position of DF Tau B relative to A with ALMA and VLTI-GRAVITY are shown with colored stars, while the solid circles show their expected position using the Allen et al. (2017) orbit. The offset from the Allen et al. (2017) orbit is within the orbital uncertainties, as shown by the red curve in the inset, which is a manual fit to the ALMA and VLTI-GRAVITY points that is within the orbital uncertainties. – astro-ph.EP

Sierra L. Grant, Nicolas T. Kurtovic, Ewine F. van Dishoeck, Thomas Henning, Inga Kamp, Hugo Nowacki, Karine Perraut, Andrea Banzatti, Milou Temmink, Valentin Christiaens, Matthias Samland, Danny Gasman, Benoît Tabone, Manuel Güdel, Pierre-Olivier Lagage, Aditya M. Arabhavi, David Barrado, Alessio Caratti o Garatti, Adrian M. Glauser, Hyerin Jang, Jayatee Kanwar, Fred Lahuis, Maria Morales-Calderón, Göran Olofsson, Giulia Perotti, Kamber Schwarz, Marissa Vlasblom, Rebeca Garcia Lopez, Feng Long

Comments: Submitted to A&A on May 17th, 2024. The reduced and calibrated JWST and ALMA data will become publicly available upon publication
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2406.10217 [astro-ph.EP] (or arXiv:2406.10217v1 [astro-ph.EP] for this version)
Submission history
From: Sierra Grant
[v1] Fri, 14 Jun 2024 17:52:13 UTC (2,875 KB)

Astrobiology, Astrochemistry,

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻