J/A+A/701/A139 XUE source properties (Ramirez-Tannus+, 2025)
XUE: JWST spectroscopy of externally irradiated disks around young
intermediate-mass stars.
Ramirez-Tannus M.C., Bik A., Getman V.K., Waters R., Portilla-Revelo B.,
Goeppl C., Winter J.A., Frediani J., Chaparro G., Feigelson D.E.,
Haworth J.T., Henning T., Hernandez S., Lemus-Nemocon M.A., Kuhn M.,
Preibisch T., Roccatagliata V., Sabbi E., van Boekel R., Zeidler P.
<Astron. Astrophys. 701, A139 (2025)>
=2025A&A...701A.139R 2025A&A...701A.139R (SIMBAD/NED BibCode)
ADC_Keywords: Stars, pre-main sequence ; Infrared sources ; Ultraviolet
Keywords: planets and satellites: formation - protoplanetary disks -
stars: pre-main sequence - infrared: ISM - infrared: stars
Abstract:
Our knowledge of the initial conditions of terrestrial planet
formation is mainly based on the study of protoplanetary disks around
nearby isolated low-mass stars. However, most young stars and
therefore planetary systems form in high-mass star-forming regions and
are exposed to ultraviolet radiation, affecting the protoplanetary
disk. These regions are located at large distances and only now with
JWST has it become accessible to study the inner disks surrounding
young stars.
We present the eXtreme UV Environments (XUE) program, which provides
the first detailed characterization of the physical and chemical
properties of the inner disks around young intermediate-mass
(1-4M☉) stars exposed to external irradiation from nearby
massive stars. We present high-signal-to-noise MIRI-MRS spectroscopy
of 12 disks located in three subclusters of the high-mass star-forming
region NGC 6357 (d∼1690pc).
Based on their mid-infrared spectral energy distribution, we
classified the XUE sources into Group I and II based on the Meeus
scheme. We analyzed their molecular emission features, and compared
their spectral indices and 10um silicate emission profiles to the ones
of nearby Herbig and intermediate T Tauri (IMTT) disks.
The XUE program provides the first detailed characterization of the
rich molecular inventory in IMTT disks, including water, CO, CO2,
HCN, and C2H2. In the XUE sample, the detected emission likely
originates from within 10au, although this inner disk origin may not
be typical for all externally irradiated disks. Despite being more
massive, the XUE stars host disks with a molecular richness comparable
to isolated T Tauri systems. The spectral indices are also consistent
with similar-mass stars in nearby regions. The 10um silicate features
in the XUE sample exhibit lower F11.3/F9.8 ratios at a given Fpeak,
suggesting that the disk surfaces may be dominated by smaller grains
compared to nearby disks. However, uncertainties in extinction prevent
us from drawing firm conclusions about their inner disk properties.
The majority of disks display water emission from the inner disk,
suggesting that even in these extreme environments rocky planets can
form in the presence of water. Only one object shows PAH emission,
contrasting with the higher PAH detection rates in IMTT surveys from
lower-UV environments.
The absence of strong line fluxes and other irradiation signatures
suggests that the XUE disks have been truncated by external UV
photons. However, this truncation does not appear to significantly
impact the chemical richness of their inner regions. These findings
indicate that even in extreme environments, IMTT disks can retain the
ingredients necessary for rocky planet formation, comparable to the
ones of lower-mass T Tauri disks in low-mass star-forming regions.
Description:
Most young stars and therefore planetary systems form in high-mass
star forming regions and are exposed to ultraviolet radiation,
affecting the protoplanetary disk. These regions are located at large
distances and only now with JWST become accessible to study the inner
disks surrounding young stars. We present the eXtreme UV Environments
(XUE) program, which provides the first detailed characterization of
the physical and chemical properties of the inner disks around young
intermediate-mass stars exposed to external irradiation from nearby
massive stars. We present high signal to noise MIRI-MRS spectroscopy
of 12 disks located in three sub-clusters of the high-mass star-
forming region NGC 6357. Based on their mid-infrared spectral energy
distribution, we classify the XUE sources into Group I and II based on
the Meeus scheme. We analyze their molecular emission features, and
compare their spectral indices and 10um silicate emission profiles to
those of nearby Herbig and intermediate T Tauri disks. Despite being
more massive, the XUE stars host disks with molecular richness
comparable to isolated T Tauri systems. The 10um silicate features
show lower F11.3/F9.8 ratios at a given Fpeak, but current
uncertainties prevent conclusions about their inner disk properties.
Most disks display water emission from the inner disk, suggesting that
even in these extreme environments rocky planets can form in the
presence of water. The absence of strong line fluxes and other
irradiation signatures suggests that the XUE disks have been truncated
by external UV photons. However, this truncation does not appear to
significantly impact the chemical richness of their inner regions.
These findings indicate that even in extreme environments, IMTT disks
can retain the ingredients necessary for rocky planet formation.
Properties of the XUE sources, including their coordinates,
luminosity, effective temperature, mass, extinction, bolometric
luminosity, X-ray luminosity, and various spectral indices. The table
also includes the properties of the water emission lines, the K, J, H,
I1, I2, I3, I4, F435W, F550M, and F850LP magnitudes, Gaia DR3
identifiers, and parallax measurements. The data are derived from the
MIRI-MRS spectra and other observations, providing a comprehensive
overview of the sources characteristics.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea2.dat 349 12 All the data used and derived in this paper
for the XUE sources
xue1fp.dat 184 10740 XUE 1 final products
xue2fp.dat 184 10740 XUE 2 final products
xue3fp.dat 184 10740 XUE 3 final products
xue4fp.dat 184 10740 XUE 4 final products
xue5fp.dat 184 10740 XUE 5 final products
xue6fp.dat 184 10740 XUE 6 final products
xue7fp.dat 184 10740 XUE 7 final products
xue8fp.dat 184 10740 XUE 8 final products
xue9fp.dat 184 10740 XUE 8 final products
xue10fp.dat 184 10740 XUE 10 final products
xue11fp.dat 184 10740 XUE 11 final products
xue12fp.dat 184 10740 XUE 12 final products
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- XUE [1/12] Source ID
4- 13 F10.6 deg RAdeg Right ascension (J2000)
15- 24 F10.6 deg DEdeg Declination (J2000)
26- 30 F5.3 --- logG0 FUV field (G0 is the Habing field)
32- 35 F4.1 mag AV Extinction
37- 38 I2 Lsun Lbol Bolometric luminosity
40- 43 I4 K Teff Effective temperature
45- 47 F3.1 Msun Mass Mass
49- 55 F7.3 [cm-2] logNH ?=-99.999 Hydrogen column density
57- 63 F7.3 [10-7W] logLX ?=-99.999 X-ray luminosity
65- 69 F5.2 --- n6-13 n6-13 spectral index (1)
71- 75 F5.2 --- n5-12 n5-12 spectral index (1)
77- 81 F5.2 --- n12-20 n12-20 spectral index (1)
83- 93 E11.3 Lsun LH2O H2O luminosity
95-105 E11.3 Lsun e_LH2O H2O luminosity (error
107-111 F5.3 --- Fpeak Peak flux, maximum value between 6 and 14um
113-117 F5.3 --- F11.3/9.8 Flux ratio F11.3um/F9.8um
119-127 F9.6 mag Kmag UKIRT K magnitude
129-140 F12.10 mag e_Kmag UKIRT K magnitude error
142-147 F6.3 mag Jmag UKIRT J magnitude
149-153 F5.3 mag e_Jmag UKIRT J magnitude error
155-160 F6.3 mag Hmag UKIRT H magnitude
162-166 F5.3 mag e_Hmag UKIRT H magnitude error
168-172 F5.2 mag I1mag IRAC 1 magnitude
174-177 F4.2 mag e_I1mag IRAC 1 magnitude error
179-183 F5.2 mag I2mag IRAC 2 magnitude
185-188 F4.2 mag e_I2mag IRAC 2 magnitude error
190-196 F7.3 mag I3mag ?=-99.999 IRAC 3 magnitude
198-204 F7.3 mag e_I3mag ?=-99.999 IRAC 3 magnitude error
206-212 F7.3 mag I4mag ?=-99.999 IRAS 4 magnitude
214-220 F7.3 mag e_I4mag ?=-99.999 IRAS 4 magnitude error
222-228 F7.3 mag F435Wmag ?=-99.999 HST F435W magnitude
230-240 F11.7 mag e_F435Wmag ?=-99.999 HST F435W magnitude error
242-248 F7.3 mag F550Mmag ?=-99.999 HST F550M magnitude
250-260 F11.7 mag e_F550Mmag ?=-99.999 HST F550M magnitude error
262-268 F7.3 mag F850LPmag ?=-99.999 HST F850LP magnitude
270-278 F9.5 mag e_F850LPmag ?=-99.999 HST F850LP magnitude error
280-307 A28 --- GaiaDR3 Gaia DR3 mane
309-328 F20.17 mas plx Parallax corrected
330-349 F20.18 mas e_plx Parallax corrected error
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Note (1): Spectral indices n6-13 , n5-12 and n12-20 defined as:
nlambda1-lambda2=
[log(lambda1*F1)-log(lambda2*F2)]/[log(lambda1)*log(lambda2)]
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Byte-by-byte Description of file: xue*fp.dat
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Bytes Format Units Label Explanations
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1- 19 F19.16 um lambda Wavelength
21- 43 E23.20 Jy Flux Flux
45- 67 E23.20 Jy FluxClip Masked flux
69- 91 E23.20 Jy FluxClipDered Dereddened and masked flux
93-111 F19.16 um lambdaMasked Masked wavelength points
113-135 E23.20 --- Cont Continuum
137-160 E24.20 Jy FluxContSubt Continuum subtracted flux
162-184 E23.20 Jy FluxClipContSubt Continuum subtracted and masked flux
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Acknowledgements:
Maria Claudia Ramirez-Tannus, ramirez(at)mpia.de
(End) Patricia Vannier [CDS] 23-Jul-2025