The Herschel/PACS view of disks around low-mass stars in Chamaleon-I

Abstract

Circumstellar disks are expected to be the birthplaces of planets. The potential for forming one or more planets of various masses is essentially driven by the initial mass of the disks. We present and analyze Herschel/PACS observations of disk-bearing M-type stars that belong to the young ~2 Myr old Chamaleon-I star forming region. We used the radiative transfer code RADMC to successfully model the SED of 17 M-type stars detected at PACS wavelengths. We first discuss the relatively low detection rates of M5 and later spectral type stars with respect to the PACS sensitivity, and argue their disks masses, or flaring indices, are likely to be low. For M0 to M3 stars, we find a relatively broad range of disk masses, scale heights, and flaring indices. Via a parametrization of dust stratification, we can reproduce the peak fluxes of the 10 $\mu$m emission feature observed with Spitzer/IRS, and find that disks around M-type stars may display signs of dust sedimentation. The Herschel/PACS observations of low-mass stars in Cha-I provide new constraints on their disk properties, overall suggesting that disk parameters for early M-type stars are comparable to those for more massive stars (e.g., comparable scale height and flaring angles). However, regions of the disks emitting at about 100 $\mu$m may still be in the optically thick regime, preventing direct determination of disk masses. Thus the modeled disk masses should be considered as lower limits. Still, we are able to extend the wavelength coverage of SED models and start characterizing effects such as dust sedimentation, an effort leading the way towards ALMA observations of these low-mass stars.

References in corpus (12)

• Protoplanetary Disk Structures in Ophiuchus
• A Submillimeter View of Circumstellar Dust Disks in $\rho$ Ophiuchus
• The Stellar Population of the Chamaeleon I Star-Forming Region
• Exploring brown dwarf disks: A 1.3 mm survey in Taurus
• The Disk Population of the Chamaeleon I Star-Forming Region
• A Multiplicity Census of Young Stars in Chamaeleon I
• New Low-Mass Stars and Brown Dwarfs with Disks in the Chamaeleon I Star-Forming Region
• Hubble and Spitzer Observations of an Edge-on Circumstellar Disk around a Brown Dwarf
• The end of star formation in Chamaeleon I ? A LABOCA census of starless and protostellar cores
• Size-sorting dust grains in the surface layers of protoplanetary disks
• A Herschel PACS survey of the dust and gas in Upper Scorpius disks
• Probing Dust Settling in Proto-planetary Disks with ALMA

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• X-Shooter study of accretion in Chamaeleon I: II. A steeper increase of accretion with stellar mass for very low mass stars?
• The (w)hole survey: an unbiased sample study of transition disk candidates based on Spitzer catalogs
• Far-infrared to millimeter data of protoplanetary disks: dust growth in the Taurus, Ophiuchus, and Chamaeleon I star-forming regions
• Transition disks: the observational revolution from SEDs to imaging
• A Herschel view of protoplanetary disks in the $\sigma$ Ori cluster
• The Frequency Of Binary Star Interlopers Amongst Transitional Discs
• An ALMA Survey of faint disks in the Chamaeleon I star-forming region: Why are some Class II disks so faint?
• Brown dwarf disks with Herschel: Linking far-infrared and (sub)-mm fluxes
• A homogeneous analysis of disks around brown dwarfs
• Constraining the properties of transitional disks in Chamaeleon I with Herschel
• The Herschel view of circumstellar discs: a multi-wavelength study of Chamaeleon I
• Herschel/PACS view of disks around low-mass stars and brown dwarfs in the TW Hya association