scholarly journals Near-infrared monitoring of the accretion outburst in the massive young stellar object S255-NIRS3

2019 ◽  
Vol 72 (1) ◽  
Author(s):  
Mizuho Uchiyama ◽  
Takuya Yamashita ◽  
Koichiro Sugiyama ◽  
Tatsuya Nakaoka ◽  
Miho Kawabata ◽  
...  
Keyword(s):  
Light Curve ◽  
Near Infrared ◽  
Stellar Object ◽  
Young Stellar Objects ◽  
Infrared Light ◽  
Continuum Emission ◽  
Sudden Increase ◽  
Maser Emission ◽  
Young Stellar Object ◽  
Band Emission

Abstract We followed up the massive young stellar object S255-NIRS3 (= S255-IRS1b) during its recent accretion outburst event in the $K_{\rm s}$ band with Kanata/HONIR for four years after its burst and obtained a long-term light curve. This is the most complete near-infrared light curve of the S255-NIRS3 burst event that has ever been presented. The light curve showed a steep increase reaching a peak flux that was 3.4 mag brighter than the quiescent phase and then a relatively moderate year-scale fading until the last observation, similar to that of the accretion burst events such as EXors found in lower-mass young stellar objects. The behavior of the $K_{\rm s}$-band light curve is similar to that observed in 6.7 GHz class II methanol maser emission, with a sudden increase followed by moderate year-scale fading. However, the maser emission peaks appear 30–50 d earlier than that of the $K_{\rm s}$ band emission. The similarities confirmed that the origins of the maser emission and the $K_{\rm s}$-band continuum emission are common, as previously shown from other infrared and radio observations by Stecklum et al. (2016, Astronomer’s Telegram, 8732), Caratti o Garatti et al. (2017b, Nature Phys., 13, 276), and Moscadelli et al. (2017, A&A, 600, L8). However, the differences in energy transfer paths, such as the exciting/emitting/scattering structures, may cause the delay in the flux-peak dates.

scholarly journals Principal component analysis tomography in near-infrared integral field spectroscopy of young stellar objects – I. Revisiting the high-mass protostar W33A

2021 ◽  
Vol 503 (1) ◽  
pp. 270-291
Author(s):  
F Navarete ◽  
A Damineli ◽  
J E Steiner ◽  
R D Blum
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Rotation Axis ◽  
Principal Component ◽  
Young Stellar Objects ◽  
High Mass ◽  
Continuum Emission ◽  
Rotating Disc ◽  
Stellar Objects ◽  
K Band

ABSTRACT W33A is a well-known example of a high-mass young stellar object showing evidence of a circumstellar disc. We revisited the K-band NIFS/Gemini North observations of the W33A protostar using principal components analysis tomography and additional post-processing routines. Our results indicate the presence of a compact rotating disc based on the kinematics of the CO absorption features. The position–velocity diagram shows that the disc exhibits a rotation curve with velocities that rapidly decrease for radii larger than 0.1 arcsec (∼250 au) from the central source, suggesting a structure about four times more compact than previously reported. We derived a dynamical mass of 10.0$^{+4.1}_{-2.2}$ $\rm {M}_\odot$ for the ‘disc + protostar’ system, about ∼33 per cent smaller than previously reported, but still compatible with high-mass protostar status. A relatively compact H2 wind was identified at the base of the large-scale outflow of W33A, with a mean visual extinction of ∼63 mag. By taking advantage of supplementary near-infrared maps, we identified at least two other point-like objects driving extended structures in the vicinity of W33A, suggesting that multiple active protostars are located within the cloud. The closest object (Source B) was also identified in the NIFS field of view as a faint point-like object at a projected distance of ∼7000 au from W33A, powering extended K-band continuum emission detected in the same field. Another source (Source C) is driving a bipolar $\rm {H}_2$ jet aligned perpendicular to the rotation axis of W33A.

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

2016 ◽  
Vol 588 ◽  
pp. A117 ◽  
Author(s):  
J. Sanchez-Bermudez ◽  
C. A. Hummel ◽  
P. Tuthill ◽  
A. Alberdi ◽  
R. Schödel ◽  
...  
Keyword(s):  
Near Infrared ◽  
Stellar Object ◽  
Young Stellar Object ◽  
Sparse Aperture

scholarly journals DETECTION OF LINEARLY POLARIZED 6.9 mm CONTINUUM EMISSION FROM THE CLASS 0 YOUNG STELLAR OBJECT NGC 1333 IRAS4A

2016 ◽  
Vol 821 (1) ◽  
pp. 41 ◽  
Author(s):  
Hauyu Baobab Liu ◽  
Shih-Ping Lai ◽  
Yasuhiro Hasegawa ◽  
Naomi Hirano ◽  
Ramprasad Rao ◽  
...  
Keyword(s):  
Stellar Object ◽  
Continuum Emission ◽  
Young Stellar Object ◽  
Linearly Polarized

scholarly journals A Search for Disks around Massive Young Stellar Objects

2004 ◽  
Vol 221 ◽  
pp. 425-430 ◽  
Author(s):  
A. G. Gibb ◽  
M. G. Hoare ◽  
L. G. Mundy ◽  
F. Wyrowski
Keyword(s):  
Near Infrared ◽  
Young Stellar Objects ◽  
Continuum Emission ◽  
Circumstellar Disk ◽  
Mass Yield ◽  
Stellar Objects ◽  
Strong Emission ◽  
Yield Values ◽  
Infrared Data ◽  
The Continuum

We present subarcsecond observations at 2.7 and 1.4 mm of a sample of massive young stellar objects made with the BIMA millimetre array. For most sources the continuum emission on the smallest scales at 2.7 mm is dominated by free-free emission from the stellar wind or jet. Strong emission at 1.4 mm shows the presence of significant dust associated with Cep A and GL 490 but our resolution is not sufficient to resolve any structure. The 2.7-mm emission from GL 490 is resolved but it is not clear whether we are seeing a single circumstellar disk or a secondary companion, although near-infrared data support the disk hypothesis. Estimates of the dust mass yield values of ∼1–4 M⊙ within radii of 150 to 1000 AU.

scholarly journals ISO-ChaI 52: a weakly accreting young stellar object with a dipper light curve

2020 ◽  
Vol 639 ◽  
pp. L8
Author(s):  
A. Frasca ◽  
C. F. Manara ◽  
J. M. Alcalá ◽  
K. Biazzo ◽  
L. Venuti ◽  
...  
Keyword(s):  
Light Curve ◽  
Spectral Energy Distribution ◽  
Stellar Object ◽  
Spectral Lines ◽  
Spectral Energy ◽  
Emission Characteristic ◽  
Disk System ◽  
Dark Cloud ◽  
Infrared Excess ◽  
Young Stellar Object

We report the discovery of periodic dips in the multiband light curve of ISO-ChaI 52, a young stellar object in the Chamaeleon I dark cloud. This is one of the peculiar objects that display very low or negligible accretion in their UV continuum and spectral lines, although they present a remarkable infrared excess emission characteristic of optically thick circumstellar disks. We have analyzed a spectrum obtained at the Very Large Telescope with the X-shooter spectrograph with the tool ROTFIT to determine the stellar parameters. The latter, along with photometry from our campaign with the Rapid Eye Mount telescope and from the literature, have allowed us to model the spectral energy distribution and to estimate the size and temperature of the inner and outer disk. Based on the rotational period of the star-disk system of 3.45 days, we estimate a disk inclination of 36°. The depth of the dips in different bands has been used to gain information about the occulting material. A single extinction law is not able to fit the observed behavior, while a two-component model of a disk warp composed of a dense region with a gray extinction and an upper layer with an extinction as in the interstellar medium provides a better fit to the data.

scholarly journals VLA Observations of Nine Extended Green Objects in the Milky Way: Ubiquitous Weak, Compact Continuum Emission, and Multi-epoch Emission from Methanol, Water, and Ammonia Masers

2021 ◽  
Vol 923 (2) ◽  
pp. 263
Author(s):  
A. P. M. Towner ◽  
C. L. Brogan ◽  
T. R. Hunter ◽  
C. J. Cyganowski
Keyword(s):  
Milky Way ◽  
Thermal Emission ◽  
Young Stellar Objects ◽  
Continuum Emission ◽  
Large Array ◽  
Spectral Indices ◽  
Physical Processes ◽  
Stellar Objects ◽  
Maser Emission ◽  
Very Large Array

Abstract We have observed a sample of nine Extended Green Objects (EGOs) at 1.3 and 5 cm with the Very Large Array (VLA) with subarcsecond resolution and ∼7–14 μJy beam−1-sensitivities in order to characterize centimeter continuum emission as it first appears in these massive protoclusters. We find an EGO-associated continu um emission—within 1″ of the extended 4.5 μm emission—in every field, which is typically faint (order 101–102 μJy) and compact (unresolved at 0″.3–0″.5). The derived spectral indices of our 36 total detections are consistent with a wide array of physical processes, including both non-thermal (19% of detections) and thermal free–free processes (e.g., ionized jets and compact H ii regions, 78% of sample) and warm dust (1 source). We also find an EGO-associated 6.7 GHz CH3OH and 22 GHz H2O maser emission in 100% of the sample and a NH3 (3,3) masers in ∼45%; we do not detect any NH3 (6,6) masers at ∼5.6 mJy beam−1 sensitivity. We find statistically-significant correlations between L radio and L bol at two physical scales and three frequencies, consistent with thermal emission from ionized jets, but no correlation between L H 2 O and L radio for our sample. From these data, we conclude that EGOs likely host multiple different centimeter continuum-producing processes simultaneously. Additionally, at our ∼1000 au resolution, we find that all EGOs except G18.89−0.47 contain 1 ∼ 2 massive sources based on the presence of CH3OH maser groups, which is consistent with our previous work suggesting that these are typical massive protoclusters, in which only one to a few of the young stellar objects are massive.

Near-infrared light curve of Comet 9P/Tempel 1 during Deep Impact

Icarus ◽  
2007 ◽  
Vol 191 (2) ◽  
pp. 424-431 ◽  
Author(s):  
Y.R. Fernández ◽  
C.M. Lisse ◽  
M.S. Kelley ◽  
N. Dello Russo ◽  
A.T. Tokunaga ◽  
...  
Keyword(s):  
Light Curve ◽  
Near Infrared ◽  
Infrared Light ◽  
Near Infrared Light ◽  
Deep Impact

scholarly journals Radio outburst from a massive (proto)star

2018 ◽  
Vol 612 ◽  
pp. A103 ◽  
Author(s):  
R. Cesaroni ◽  
L. Moscadelli ◽  
R. Neri ◽  
A. Sanna ◽  
A. Caratti o Garatti ◽  
...  
Keyword(s):  
Flux Density ◽  
Mass Loss Rate ◽  
Strong Support ◽  
Stellar Object ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Opening Angle ◽  
Very Large Array ◽  
Young Stellar Object ◽  
Radio Outburst

Context. Recent observations of the massive young stellar object S255 NIRS 3 have revealed a large increase in both methanol maser flux density and IR emission, which have been interpreted as the result of an accretion outburst, possibly due to instabilities in a circumstellar disk. This indicates that this type of accretion event could be common in young/forming early-type stars and in their lower mass siblings, and supports the idea that accretion onto the star may occur in a non-continuous way. Aims. As accretion and ejection are believed to be tightly associated phenomena, we wanted to confirm the accretion interpretation of the outburst in S255 NIRS 3 by detecting the corresponding burst of the associated thermal jet. Methods. We monitored the radio continuum emission from S255 NIRS 3 at four bands using the Karl G. Jansky Very Large Array. The millimetre continuum emission was also observed with both the Northern Extended Millimeter Array of IRAM and the Atacama Large Millimeter/Submillimeter Array. Results. We have detected an exponential increase in the radio flux density from 6 to 45 GHz starting right after July 10, 2016, namely ~13 months after the estimated onset of the IR outburst. This is the first ever detection of a radio burst associated with an IR accretion outburst from a young stellar object. The flux density at all observed centimetre bands can be reproduced with a simple expanding jet model. At millimetre wavelengths we infer a marginal flux increase with respect to the literature values and we show this is due to free–free emission from the radio jet. Conclusions. Our model fits indicate a significant increase in the jet opening angle and ionized mass loss rate with time. For the first time, we can estimate the ionization fraction in the jet and conclude that this must be low (<14%), lending strong support to the idea that the neutral component is dominant in thermal jets. Our findings strongly suggest that recurrent accretion + ejection episodes may be the main route to the formation of massive stars.

Near-infrared light curve of Comet 9P/Tempel 1 during Deep Impact

Icarus ◽  
2007 ◽  
Vol 187 (1) ◽  
pp. 220-227 ◽  
Author(s):  
Y.R. Fernández ◽  
C.M. Lisse ◽  
M.S. Kelley ◽  
N. Dello Russo ◽  
A.T. Tokunaga ◽  
...  
Keyword(s):  
Light Curve ◽  
Near Infrared ◽  
Infrared Light ◽  
Near Infrared Light ◽  
Deep Impact
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