MINDS: The very low-mass star and brown dwarf sample. Detections and trends in the inner disk gas

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Main Authors: Arabhavi, A. M., Kamp, I., Henning, Th., van Dishoeck, E. F., Jang, H., Waters, L. B. F. M., Christiaens, V., Gasman, D., Pascucci, I., Perotti, G., Grant, S. L., Güdel, M., Lagage, P. -O., Barrado, D., Garatti, A. Caratti o, Lahuis, F., Kaeufer, T., Kanwar, J., Morales-Calderón, M., Schwarz, K., Sellek, A. D., Tabone, B., Temmink, M., Vlasblom, M., Patapis, P.
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Published: 2025
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author Arabhavi, A. M.
Kamp, I.
Henning, Th.
van Dishoeck, E. F.
Jang, H.
Waters, L. B. F. M.
Christiaens, V.
Gasman, D.
Pascucci, I.
Perotti, G.
Grant, S. L.
Güdel, M.
Lagage, P. -O.
Barrado, D.
Garatti, A. Caratti o
Lahuis, F.
Kaeufer, T.
Kanwar, J.
Morales-Calderón, M.
Schwarz, K.
Sellek, A. D.
Tabone, B.
Temmink, M.
Vlasblom, M.
Patapis, P.
author_facet Arabhavi, A. M.
Kamp, I.
Henning, Th.
van Dishoeck, E. F.
Jang, H.
Waters, L. B. F. M.
Christiaens, V.
Gasman, D.
Pascucci, I.
Perotti, G.
Grant, S. L.
Güdel, M.
Lagage, P. -O.
Barrado, D.
Garatti, A. Caratti o
Lahuis, F.
Kaeufer, T.
Kanwar, J.
Morales-Calderón, M.
Schwarz, K.
Sellek, A. D.
Tabone, B.
Temmink, M.
Vlasblom, M.
Patapis, P.
contents Planet-forming disks around brown dwarfs and very low-mass stars (VLMS) are on average less massive and are expected to undergo faster radial solid transport than their higher mass counterparts. Spitzer had detected C$_2$H$_2$, CO$_2$ and HCN around these objects. With better sensitivity and spectral resolving power, JWST recently revealed incredibly carbon-rich spectra from such disks. A study of a larger sample of objects is necessary to understand how common such carbon-rich inner disk regions are and to put constraints on their evolution. We present and analyze MIRI observations of 10 disks around VLMS from the MIRI GTO program. This sample is diverse, with the central object ranging in mass from 0.02 to 0.14 $M_{\odot}$. They are located in three star-forming regions and a moving group (1-10 Myr). We identify molecular emission in all sources and report detection rates. We compare the molecular flux ratios between different species and to dust emission strengths. We also compare the flux ratios with the stellar and disk properties. The spectra of these VLMS disks are extremely molecular rich, and we detect the 10 $μ$m silicate dust emission feature in 70% of the sample. We detect C$_2$H$_2$ and HCN in all of the sources and find larger hydrocarbons such as C$_4$H$_2$ and C$_6$H$_6$ in nearly all sources. Among O-bearing molecules, we find firm detections of CO$_2$, H$_2$O, and CO in 90%, 50%, and 20% of the sample, respectively. We find that the detection rates of organic molecules correlate with other organic molecules and anti-correlate with inorganic molecules. Hydrocarbon-rich sources show a weaker 10$μ$m dust strength as well as lower disk dust mass than the oxygen-rich sources. We find potential evidence for C/O enhancement with disk age. The observed trends are consistent with models that suggest rapid inward solid material transport and grain growth.
format Preprint
id arxiv_https___arxiv_org_abs_2506_02748
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle MINDS: The very low-mass star and brown dwarf sample. Detections and trends in the inner disk gas
Arabhavi, A. M.
Kamp, I.
Henning, Th.
van Dishoeck, E. F.
Jang, H.
Waters, L. B. F. M.
Christiaens, V.
Gasman, D.
Pascucci, I.
Perotti, G.
Grant, S. L.
Güdel, M.
Lagage, P. -O.
Barrado, D.
Garatti, A. Caratti o
Lahuis, F.
Kaeufer, T.
Kanwar, J.
Morales-Calderón, M.
Schwarz, K.
Sellek, A. D.
Tabone, B.
Temmink, M.
Vlasblom, M.
Patapis, P.
Earth and Planetary Astrophysics
Astrophysics of Galaxies
Solar and Stellar Astrophysics
Planet-forming disks around brown dwarfs and very low-mass stars (VLMS) are on average less massive and are expected to undergo faster radial solid transport than their higher mass counterparts. Spitzer had detected C$_2$H$_2$, CO$_2$ and HCN around these objects. With better sensitivity and spectral resolving power, JWST recently revealed incredibly carbon-rich spectra from such disks. A study of a larger sample of objects is necessary to understand how common such carbon-rich inner disk regions are and to put constraints on their evolution. We present and analyze MIRI observations of 10 disks around VLMS from the MIRI GTO program. This sample is diverse, with the central object ranging in mass from 0.02 to 0.14 $M_{\odot}$. They are located in three star-forming regions and a moving group (1-10 Myr). We identify molecular emission in all sources and report detection rates. We compare the molecular flux ratios between different species and to dust emission strengths. We also compare the flux ratios with the stellar and disk properties. The spectra of these VLMS disks are extremely molecular rich, and we detect the 10 $μ$m silicate dust emission feature in 70% of the sample. We detect C$_2$H$_2$ and HCN in all of the sources and find larger hydrocarbons such as C$_4$H$_2$ and C$_6$H$_6$ in nearly all sources. Among O-bearing molecules, we find firm detections of CO$_2$, H$_2$O, and CO in 90%, 50%, and 20% of the sample, respectively. We find that the detection rates of organic molecules correlate with other organic molecules and anti-correlate with inorganic molecules. Hydrocarbon-rich sources show a weaker 10$μ$m dust strength as well as lower disk dust mass than the oxygen-rich sources. We find potential evidence for C/O enhancement with disk age. The observed trends are consistent with models that suggest rapid inward solid material transport and grain growth.
title MINDS: The very low-mass star and brown dwarf sample. Detections and trends in the inner disk gas
topic Earth and Planetary Astrophysics
Astrophysics of Galaxies
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2506.02748