2016A&A...588A.117S


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.02CET03:21:56

2016A&A...588A.117S - Astronomy and Astrophysics, volume 588A, 117-117 (2016/4-1)

Unveiling the near-infrared structure of the massive-young stellar object NGC 3603 IRS 9A* with sparse aperture masking and spectroastrometry.

SANCHEZ-BERMUDEZ J., HUMMEL C.A., TUTHILL P., ALBERDI A., SCHODEL R., LACOUR S. and STANKE T.

Abstract (from CDS):

Context. Contemporary theory holds that massive stars gather mass during their initial phases via accreting disk-like structures. However, conclusive evidence for disks has remained elusive for most massive young objects. This is mainly due to significant observational challenges: objects are rare and located at great distances within dusty, highly opaque environments. Incisive studies, even targeting individual objects, are therefore relevant to the progression of the field. NGC 3603 IRS 9A* is a young massive stellar object that is still surrounded by an envelope of molecular gas for which previous mid-infrared observations with long-baseline interferometry have provided evidence of a plausible disk of 50 mas diameter at its core.
Aims. This work aims at a comprehensive study of the physics and morphology of IRS 9A at near-infrared wavelengths.
Methods. New sparse aperture-masking interferometry data, taken with the near-infrared camera NACO of the Very Large Telescope (VLT) at Ks and L' wavelengths, were analyzed together with archival high-resolution H2 and Brγ lines obtained with the cryogenic high-resolution infrared schelle spectrograph (CRIRES).
Results. The trends in the calibrated visibilities at Ks and L'-bands suggest the presence of a partially resolved compact object with an angular size of <=30mas at the core of IRS 9A, together with the presence of over-resolved flux. The spectroastrometric signal of the H2 line, obtained from the CRIRES spectra, shows that this spectral feature proceeds from the large-scale extended emission (∼300mas), while the Brγ line appears to be formed at the core of the object (∼20mas). To better understand the physics that drive IRS 9A, we have performed continuum radiative transfer modeling. Our best model supports the existence of a compact disk with an angular diameter of 20mas, together with an outer envelope of 1'' exhibiting a polar cavity with an opening angle of ∼30°. This model reproduces the MIR morphology that has previously been derived in the literature and also matches the spectral energy distribution (SED) of the source.
Conclusions. Our observations and modeling of IRS 9A support the presence of a disk at the core, surrounded by an envelope. This scenario is consistent with the brightness distribution (SED) of the source for near- and mid-infrared wavelengths at various spatial scales. However, our model suffers from remaining inconsistencies between SED modelling and the interferometric data. Moreover, the Brγ spectroastrometric signal indicates that the core of IRS 9A exhibits some form of complexity such as asymmetries in the disk. Future high-resolution observations are required to confirm the disk/envelope model and to flesh out the details of the physical form of the inner regions of IRS 9A.

Abstract Copyright: © ESO, 2016

Journal keyword(s): techniques: high angular resolution - infrared: stars - stars: formation - stars: massive - stars: protostars

Simbad objects: 17

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Number of rows : 17

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 RAFGL 989 Y*O 06 41 10.1592954288 +09 29 33.635497596   17.4 16.8 18.26 17.28 B2 245 0
2 V* Z CMa Ae* 07 03 43.1588002461 -11 33 06.230351311 10.51 9.99 8.80     B5/8eq+F5/7 537 3
3 HD 97398 * 11 11 40.3837052216 -60 18 38.949935343   6.631 6.677     B8V 20 0
4 Cl* NGC 3603 MTT 122 * 11 15 09.45 -61 16 41.4           ~ 20 0
5 [FPA77] NGC 3603 IRS 9A IR 11 15 11.34 -61 16 45.2           ~ 18 0
6 NGC 3603 OpC 11 15 18.6 -61 15 26           ~ 970 1
7 HD 98133 PM* 11 16 28.4810991943 -60 34 04.305542990   9.15 8.57     G0V 11 0
8 HD 98194 * 11 16 50.8854752977 -61 05 07.975940335   9.51 9.04     F3/5V 15 0
9 RAFGL 4176 IR 13 43 01.704 -62 08 51.23           ~ 94 0
10 IRAS 13481-6124 Y*O 13 51 37.85568 -61 39 07.5168           ~ 41 0
11 EM* AS 220 Ae* 17 10 08.1238 -27 15 18.801 12.86 12.79 12.22 12.03 10.82 A6Ve+G5Ve 132 0
12 HD 327083 s*b 17 15 15.3714469957 -40 20 06.793634106 12.07 11.44 10.00 9.64   B6Ieq 54 0
13 NAME M 8E IR Y*O 18 04 53.9 -24 26 41           ~ 82 0
14 W 33a Y*O 18 14 39.0 -17 52 03           ~ 593 0
15 MSX5C G014.9957-00.6735 IR 18 20 19.7 -16 13 31           ~ 37 2
16 NAME M 17 SW SFR 18 20 23.1 -16 11 43           ~ 254 0
17 RAFGL 2136 SFR 18 22 26.8740 -13 30 17.177           ~ 254 0

    Equat.    Gal    SGal    Ecl

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2021.03.02-03:21:56

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