New Millimeter CO Observations of the Gas-rich Debris Disks 49 Cet and HD 32297

Moór, A.; Kral, Quentin; Ábrahám, P.; Kóspál, Á.; Dutrey, Anne; Folco, E. Di; Hughes, A. Meredith; Juhász, A.; Pascucci, Ilaria; Pawellek, N.

doi:10.3847/1538-4357/ab4272

Cited by 46 publications

(79 citation statements)

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“…In this latter case, the model does not give us a unique answer regarding the event time, other than that it must be greater than ∼ 10 5 yr. For comparison, the system lifetime is larger than 15 Myr. The CO production rate of 15 M ⊕ Myr −1 is in contrast with the result from Moór et al (2019), where they found that P CO ≈ 3.6 × 10 −2 M ⊕ Myr −1 . However, the Moór et al (2019) model over-predicts the C 0 mass by a factor 10 compared to our data, despite underestimating the CO break-down rate due to the different treatment of shielding (section 4.1).…”

Section: Full Calculationmentioning

confidence: 58%

“…via re-capture by dust grains). The shielding aspect of our model is similar in spirit to that in Kral et al (2019); Moór et al (2019); Marino et al (2020), but differs (substantially) in the treatment of shielding.…”

Section: Time Evolution Modelmentioning

confidence: 63%

“…Although O I 63 µm emission was not detected by Herschel (Donaldson et al 2013), we expect O to be at least as abundant as C, thanks to photodissociation of CO, CO 2 and H 2 O, all of which should be present in the cometary parent bodies. Moór et al 2019) and C 0 (3.5 × 10 −3 M⊕, this work) masses respectively, with the dashed lines corresponding to the ±3σ uncertainty ranges. The correct parameters lie where these two sets of lines intersect.…”

Section: Carbon Removal By Dust Grains and Co Re-formationmentioning

confidence: 79%

“…The destruction rate Dy C z O can be calculated if masses of all CO isotopologues and of C 0 are known (equation 9). However, as mentioned above, only the C 18 O mass is well measured (Moór et al 2019). To proceed, we first compute the 12 CO and 13 CO masses using the measured C 18 O mass, assuming ISM ratios: 13 CO/ 12 CO = 1.4 × 10 −2 and C 18 O/ 12 CO = 1.8 × 10 −3 (Wilson 1999).…”

Section: Steady-state Solutionmentioning

confidence: 99%

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Herschel SPIRE Point Source Catalogue

2017

Herschel SPIRE Point Source Catalogue

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Gas has been detected in a number of debris disks. It is likely secondary, i.e. produced by colliding solids. Here, we report ALMA Band 8 observations of neutral carbon in the CO-rich debris disk around the 15-30 Myr old A-type star HD 32297. We find that C 0 is located in a ring at ∼110 au with a FWHM of ∼80 au, and has a mass of (3.5 ± 0.2) × 10 −3 M ⊕ . Naively, such a surprisingly small mass can be accumulated from CO photo-dissociation in a time as short as ∼10 4 yr. We develop a simple model for gas production and destruction in this system, properly accounting for CO self-shielding and shielding by neutral carbon, and introducing a removal mechanism for carbon gas. We find that the most likely scenario to explain both C 0 and CO observations, is one where the carbon gas is rapidly removed on a timescale of order a thousand years and the system maintains a very high CO production rate of ∼15 M ⊕ Myr −1 , much higher than the rate of dust grind-down. We propose a possible scenario to meet these peculiar conditions: the capture of carbon onto dust grains, followed by rapid CO re-formation and re-release. In steady state, CO would continuously be recycled, producing a CO-rich gas ring that shows no appreciable spreading over time. This picture might be extended to explain other gas-rich debris disks.

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Section: Full Calculationmentioning

confidence: 58%

Section: Time Evolution Modelmentioning

confidence: 63%

Section: Carbon Removal By Dust Grains and Co Re-formationmentioning

confidence: 79%

Section: Steady-state Solutionmentioning

confidence: 99%

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Herschel SPIRE Point Source Catalogue

2017

Herschel SPIRE Point Source Catalogue

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“…If we scale those thresholds by ν 2 (assuming optically thick emission) and by d 2 to account for the difference in distance to the 49 Ceti system, then our upper limits on the integrated HCO + (4-3) and HCN(4-3) flux from Ceti are about a factor of 50 below the sensitivity of theÖberg et al (2010,2011) survey. The CO(2-1) emission from 49 Ceti (3.87 ± 0.41 Jy km s −1 , Moór et al 2019) is 26 times lower than the average for the disks in theÖberg et al ( 2011) survey, and 10 times lower than the faintest disk in the survey. Looking at it another way, the ratio of HCO + /CO flux within a given band varies in theÖberg et al (2010,2011) sample between 0.11 and 0.59, while the ratio for 49 Ceti at Band 7 is < 0.006.…”

Section: Comparison With Observed Molecular Abundances Of Protoplanetary Disks and Cometsmentioning

confidence: 62%

A Deep Search for Five Molecules in the Debris Disk around 49 Ceti

Klusmeyer¹

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Surprisingly strong CO emission has been observed from more than a dozen debris disks around nearby main-sequence stars. The origin of this CO is unclear, in particular whether it is left over from the protoplanetary disk phase or is second-generation material released from collisions between icy bodies like debris dust. The primary unexplored avenue for distinguishing the origin of the material is understanding its molecular composition. Here we present a deep search for five molecules (CN, HCN, HCO + , SiO, and CH 3 OH) in the debris disk around 49 Ceti. We take advantage of the high sensitivity of the Atacama Large Millimeter/submillimeter Array (ALMA) at Band 7 to integrate for 3.2 hours at modest spatial (1") and spectral (0.8 km s −1 ) resolution. Our search yields stringent upper limits on the flux of all surveyed molec-

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The formation of planetary systems with SPICA

Kamp

Honda

Nomura

et al. 2021

Publ. Astron. Soc. Aust.

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In this era of spatially resolved observations of planet-forming disks with Atacama Large Millimeter Array (ALMA) and large ground-based telescopes such as the Very Large Telescope (VLT), Keck, and Subaru, we still lack statistically relevant information on the quantity and composition of the material that is building the planets, such as the total disk gas mass, the ice content of dust, and the state of water in planetesimals. SPace Infrared telescope for Cosmology and Astrophysics (SPICA) is an infrared space mission concept developed jointly by Japan Aerospace Exploration Agency (JAXA) and European Space Agency (ESA) to address these questions. The key unique capabilities of SPICA that enable this research are (1) the wide spectral coverage $10{-}220\,\mu\mathrm{m}$ , (2) the high line detection sensitivity of $(1{-}2) \times 10^{-19}\,\mathrm{W\,m}^{-2}$ with $R \sim 2\,000{-}5\,000$ in the far-IR (SAFARI), and $10^{-20}\,\mathrm{W\,m}^{-2}$ with $R \sim 29\,000$ in the mid-IR (SPICA Mid-infrared Instrument (SMI), spectrally resolving line profiles), (3) the high far-IR continuum sensitivity of 0.45 mJy (SAFARI), and (4) the observing efficiency for point source surveys. This paper details how mid- to far-IR infrared spectra will be unique in measuring the gas masses and water/ice content of disks and how these quantities evolve during the planet-forming period. These observations will clarify the crucial transition when disks exhaust their primordial gas and further planet formation requires secondary gas produced from planetesimals. The high spectral resolution mid-IR is also unique for determining the location of the snowline dividing the rocky and icy mass reservoirs within the disk and how the divide evolves during the build-up of planetary systems. Infrared spectroscopy (mid- to far-IR) of key solid-state bands is crucial for assessing whether extensive radial mixing, which is part of our Solar System history, is a general process occurring in most planetary systems and whether extrasolar planetesimals are similar to our Solar System comets/asteroids. We demonstrate that the SPICA mission concept would allow us to achieve the above ambitious science goals through large surveys of several hundred disks within $\sim\!2.5$ months of observing time.

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New Millimeter CO Observations of the Gas-rich Debris Disks 49 Cet and HD 32297

Cited by 46 publications

References 100 publications

Herschel SPIRE Point Source Catalogue

Herschel SPIRE Point Source Catalogue

A Deep Search for Five Molecules in the Debris Disk around 49 Ceti

The formation of planetary systems with SPICA

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