Browsing by Author "Chandler, Claire J."

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    Chemical and Physical Characterization of the Isolated Protostellar Source CB68: FAUST IV
    (IOP Publishing, 2022) Imai, Muneaki; Oya, Yoko; Svoboda, Brian; Liu, Hauyu Baobab; Lefloch, Bertrand; Viti, Serena; Zhang, Yichen; Ceccarelli, Cecilia; Codella, Claudio; Chandler, Claire J.; Sakai, Nami; Aikawa, Yuri; Alves, Felipe O.; Balucani, Nadia; Bianchi, Eleonora; Bouvier, Mathilde; Busquet, Gemma; Caselli, Paola; Caux, Emmanuel; Charnley, Steven; Choudhury, Spandan; Cuello, Nicolas; Simone, Marta De; Dulieu, Francois; Durán, Aurora; Evans, Lucy; Favre, Cécile; Fedele, Davide; Feng, Siyi; Fontani, Francesco; Francis, Logan; Hama, Tetsuya; Hanawa, Tomoyuki; Herbst, Eric; Hirano, Shingo; Hirota, Tomoya; Isella, Andrea; Jímenez-Serra, Izaskun; Johnstone, Doug; Kahane, Claudine; Gal, Romane Le; Loinard, Laurent; López-Sepulcre, Ana; Maud, Luke T.; Maureira, María José; Menard, Francois; Mercimek, Seyma; Miotello, Anna; Moellenbrock, George; Mori, Shoji; Murillo, Nadia M.; Nakatani, Riouhei; Nomura, Hideko; Oba, Yasuhiro; O'Donoghue, Ross; Ohashi, Satoshi; Okoda, Yuki; Ospina-Zamudio, Juan; Pineda, Jaime; Podio, Linda; Rimola, Albert; Sakai, Takeshi; Segura-Cox, Dominique; Shirley, Yancy; Taquet, Vianney; Testi, Leonardo; Vastel, Charlotte; Watanabe, Naoki; Watanabe, Yoshimasa; Witzel, Arezu; Xue, Ci; Zhao, Bo; Yamamoto, Satoshi
    The chemical diversity of low-mass protostellar sources has so far been recognized, and environmental effects are invoked as its origin. In this context, observations of isolated protostellar sources without the influence of nearby objects are of particular importance. Here, we report the chemical and physical structures of the low-mass Class 0 protostellar source IRAS 16544−1604 in the Bok globule CB 68, based on 1.3 mm Atacama Large Millimeter/submillimeter Array observations at a spatial resolution of ∼70 au that were conducted as part of the large program FAUST. Three interstellar saturated complex organic molecules (iCOMs), CH3OH, HCOOCH3, and CH3OCH3, are detected toward the protostar. The rotation temperature and the emitting region size for CH3OH are derived to be 131 ± 11 K and ∼10 au, respectively. The detection of iCOMs in close proximity to the protostar indicates that CB 68 harbors a hot corino. The kinematic structure of the C18O, CH3OH, and OCS lines is explained by an infalling–rotating envelope model, and the protostellar mass and the radius of the centrifugal barrier are estimated to be 0.08–0.30 M ⊙ and <30 au, respectively. The small radius of the centrifugal barrier seems to be related to the small emitting region of iCOMs. In addition, we detect emission lines of c-C3H2 and CCH associated with the protostar, revealing a warm carbon-chain chemistry on a 1000 au scale. We therefore find that the chemical structure of CB 68 is described by a hybrid chemistry. The molecular abundances are discussed in comparison with those in other hot corino sources and reported chemical models.
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    Misaligned Rotations of the Envelope, Outflow, and Disks in the Multiple Protostellar System of VLA 1623–2417: FAUST. III
    (IOP Publishing, 2022) Ohashi, Satoshi; Codella, Claudio; Sakai, Nami; Chandler, Claire J.; Ceccarelli, Cecilia; Alves, Felipe; Fedele, Davide; Hanawa, Tomoyuki; Durán, Aurora; Favre, Cécile; López-Sepulcre, Ana; Loinard, Laurent; Mercimek, Seyma; Murillo, Nadia M.; Podio, Linda; Zhang, Yichen; Aikawa, Yuri; Balucani, Nadia; Bianchi, Eleonora; Bouvier, Mathilde; Busquet, Gemma; Caselli, Paola; Caux, Emmanuel; Charnley, Steven; Choudhury, Spandan; Cuello, Nicolas; Simone, Marta De; Dulieu, Francois; Evans, Lucy; Feng, Siyi; Fontani, Francesco; Francis, Logan; Hama, Tetsuya; Herbst, Eric; Hirano, Shingo; Hirota, Tomoya; Imai, Muneaki; Isella, Andrea; Jímenez-Serra, Izaskun; Johnstone, Doug; Kahane, Claudine; Gal, Romane Le; Lefloch, Bertrand; Maud, Luke T.; Maureira, María José; Menard, Francois; Miotello, Anna; Moellenbrock, George; Mori, Shoji; Nakatani, Riouhei; Nomura, Hideko; Oba, Yasuhiro; O'Donoghue, Ross; Okoda, Yuki; Ospina-Zamudio, Juan; Oya, Yoko; Pineda, Jaime; Rimola, Albert; Sakai, Takeshi; Segura-Cox, Dominique; Shirley, Yancy; Svoboda, Brian; Taquet, Vianney; Testi, Leonardo; Vastel, Charlotte; Viti, Serena; Watanabe, Naoki; Watanabe, Yoshimasa; Witzel, Arezu; Xue, Ci; Zhao, Bo; Yamamoto, Satoshi
    We report a study of the low-mass Class 0 multiple system VLA 1623AB in the Ophiuchus star-forming region, using H13CO+ (J = 3–2), CS (J = 5–4), and CCH (N = 3–2) lines as part of the ALMA Large Program FAUST. The analysis of the velocity fields revealed the rotation motion in the envelope and the velocity gradients in the outflows (about 2000 au down to 50 au). We further investigated the rotation of the circumbinary VLA 1623A disk, as well as the VLA 1623B disk. We found that the minor axis of the circumbinary disk of VLA 1623A is misaligned by about 12° with respect to the large-scale outflow and the rotation axis of the envelope. In contrast, the minor axis of the circumbinary disk is parallel to the large-scale magnetic field according to previous dust polarization observations, suggesting that the misalignment may be caused by the different directions of the envelope rotation and the magnetic field. If the velocity gradient of the outflow is caused by rotation, the outflow has a constant angular momentum and the launching radius is estimated to be 5–16 au, although it cannot be ruled out that the velocity gradient is driven by entrainments of the two high-velocity outflows. Furthermore, we detected for the first time a velocity gradient associated with rotation toward the VLA 16293B disk. The velocity gradient is opposite to the one from the large-scale envelope, outflow, and circumbinary disk. The origin of its opposite gradient is also discussed.
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    The Millimeter Continuum Size–Frequency Relationship in the UZ Tau E Disk
    (IOP, 2018) Tripathi, Anjali; Andrews, Sean M.; Birnstiel, Tilman; Chandler, Claire J.; Isella, Andrea; Pérez, Laura M.; Harris, R.J.; Ricci, Luca; Wilner, David J.; Carpenter, John M.; Calvet, N.; Corder, S.A.; Deller, A.T.; Dullemond, C.P.; Greaves, J.S.; Henning, Th.; Kwon, W.; Lazio, J.; Linz, H.; Testi, L.
    We present high spatial resolution observations of the continuum emission from the young multiple star system UZ Tau at frequencies from 6 to 340 GHz. To quantify the spatial variation of dust emission in the UZ Tau E circumbinary disk, the observed interferometric visibilities are modeled with a simple parametric prescription for the radial surface brightnesses at each frequency. We find evidence that the spectrum steepens with radius in the disk, manifested as a positive correlation between the observing frequency and the radius that encircles a fixed fraction of the emission (R eff ∝ ν 0.34±0.08). The origins of this size–frequency relation are explored in the context of a theoretical framework for the growth and migration of disk solids. While that framework can reproduce a similar size–frequency relation, it predicts a steeper spectrum than that observed. Moreover, it comes closest to matching the data only on timescales much shorter (≤1 Myr) than the putative UZ Tau age (~2–3 Myr). These discrepancies are direct consequences of the rapid radial drift rates predicted by models of dust evolution in a smooth gas disk. One way to mitigate that efficiency problem is to invoke small-scale gas pressure modulations that locally concentrate drifting solids. If such particle traps reach high-continuum optical depths at 30–340 GHz with a ~30%–60% filling fraction in the inner disk (r lesssim 20 au), they can also explain the observed spatial gradient in the UZ Tau E disk spectrum.