J/A+A/481/345 SED evolution in massive young stellar objects (Molinari+, 2008)
The evolution of the spectral energy distribution in massive young stellar
objects.
Molinari S., Pezzuto S., Cesaroni R., Brand J., Faustini F., Testi L.
<Astron. Astrophys., 481, 345-365 (2008)>
=2008A&A...481..345M 2008A&A...481..345M
ADC_Keywords: Associations, stellar ; Infrared sources ; Energy distributions
Keywords: stars: formation - stars: pre-main sequence
Abstract:
The mechanism of formation of massive stars is still a matter of
debate. It is not yet clear if it can be considered to be a scaled-up
analogue of the low-mass star regime, or if there are additional
agents like merging of lower-mass forming objects or accretion from
initially unbound material. Most of the uncertainties come from the
lack of diagnostic tools to evolutionarily classify large samples of
candidate massive protostellar objects that can then be studied in
more detail.
We want to verify whether diagnostic tools like the SED shape and the
relationship between envelope mass and bolometric luminosity can be
extended to the study of high-mass star formation.
The 8-1200um SED of YSOs in 42 regions of massive star formation
has been reconstructed using MSX, IRAS, and submm data partly
available from previous works. Apart from IRAS catalogue fluxes, the
fluxes in the Mid-IR and sub-mm/mm were derived directly from the
images. The SEDs were fitted to an extensive grid of envelope models
with embedded ZAMS stars, available from the literature. Sources that
could not be fitted with a single model were then fitted with a
two-component model composed of an embedded ZAMS for the mid-IR part
and a single-temperature optically thin greybody for the longer
wavelength emitting component. Sources were classified as "IR" if
they were fitted with an embedded ZAMS envelope, and "MM" if they
could only be fitted with a greybody with a peak at high λ
further subclassification was based on being the most massive object
in the field ("P", for primary) or not ("S", for secondary).
Description:
We selected 42 sources from the original sample of Molinari et al.
(1996, Cat. J/A+A/308/573) and from the complementary sample
collected (Fontani et al., 2005, Cat. J/A+A/432/921) for the portion
of the southern sky (DE≤30°) that was left out in the Molinari et
al. (1996, Cat. J/A+A/308/573) work.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 50 42 List of sources
table2.dat 41 65 Sub-mm and mm fluxes
table3.dat 51 90 Mid-IR MSX fluxes
table4.dat 33 9 Mid-IR ISOCAM fluxes
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See also:
J/A+A/308/573 : Ammonia on YSOs IRAS sources (Molinari+ 1996)
J/A+A/432/921 : Massive protostellar candidates (Fontani+, 2005)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- IRAS IRAS field
12- 13 I2 h RAh Right ascension (J2000)
15- 16 I2 min RAm Right ascension (J2000)
18- 21 F4.1 s RAs Right ascension (J2000)
23 A1 --- DE- Declination sign (J2000)
24- 25 I2 deg DEd Declination (J2000)
27- 28 I2 arcmin DEm Declination (J2000)
30- 33 F4.1 arcsec DEs Declination (J2000)
35- 38 F4.2 mag [25-12] IRAS [25-12] colour index
39 A1 --- n_[25-12] [*] * for high sources
(else low sources, i.e. [25-12]<0.57)
41- 45 F5.2 kpc Dkin Kinematical distance, or lower limit of
kinematical distance when interval
46 A1 --- --- [-]
47- 50 F4.1 kpc Dkinu ? Upper limit of kinematical distance
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- IRAS IRAS field
12 I1 --- MM [1/8] mm peak number (1)
14- 17 I4 arcsec oRA Offset in RA mm peak (G1)
19- 22 I4 arcsec oDE Offset in DE mm peak (G1)
24- 28 F5.2 Jy F450um ? Flux at 450um
30- 34 F5.2 Jy F850um ? Flux at 850um
35 A1 --- n_F850um [b] b: Blended with MM1@850um
37- 40 F4.2 Jy F1.2mm ? Flux at 1200um
41 A1 --- n_F1.2mm [a] a : Obtained at IRAM-30m (HPBW∼10")
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Note (1): mm peaks identified as [MPC2008] IRAS MM N in Simbad.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- IRAS IRAS field
12 A1 --- IR [A-I] IR peak designation (1)
13 A1 --- n_IR [a] Peak observed with ISOCAM (2)
14- 17 I4 arcsec oRA Offset in RA of IR peak (G1)
19- 22 I4 arcsec oDE Offset in DE of IR peak (G1)
24- 28 F5.2 Jy F8.3um ?=- Flux at 8.3um (MSX A band)
30- 35 F6.2 Jy F12.1um ?=- Flux at 12.1um (MSC C band)
38- 43 F6.2 Jy F14.7um ?=- Flux at 14.7um (MSC D band)
46- 51 F6.2 Jy F21.4um ?=- Flux at 21.4um (MSC E band)
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Note (1): IR peaks identified as [MPC2008] IRAS IR A in Simbad.
Note (2): a = Source also observed with ISOCAM in LW2 and LW3 filters
(see Table 4).
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- IRAS IRAS field
12- 13 A2 --- IR [AB 1-3] IR peak designation (1)
15- 17 I3 arcsec oRA Offset in RA of IR peak (G1)
19- 21 I3 arcsec oDE Offset in DE of IR peak (G1)
23- 27 F5.2 Jy F6.75um ?=- Flux at 6.75um (ISOCAM LW2 filter)
29- 33 F5.2 Jy F15um ?=- Flux at 15um (ISOCAM LW3 filter)
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Note (1): IR peaks identified as [MPC2008] IRAS IR AN in Simbad.
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Global notes:
Note (G1): Offsets from IRAS field position as indicated in table1
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 23-Jun-2008