scholarly journals Complex structure of a proto-brown dwarf

2021 ◽  
Author(s):  
B Riaz ◽  
M N Machida
Keyword(s):  
Complex Structure ◽  
Brown Dwarf ◽  
Moment Maps ◽  
Molecular Outflow ◽  
Outflow Rate ◽  
Chemical Modelling ◽  
Stage System ◽  
Low Mass ◽  
Partial View ◽  
The Moment

Abstract We present ALMA 12CO (2-1), 13CO (2-1), C18O (2-1) molecular line observations of a very young proto-brown dwarf system, ISO-OPH 200. We have conducted physical+chemical modelling of the complex internal structure for this system using the core collapse simulations for brown dwarf formation. The model at an age of ∼6000 yr can provide a good fit to the observed kinematics, spectra, and reproduce the complex structures seen in the moment maps. Results from modelling indicate that 12CO emission is tracing an extended (∼1000 au) molecular outflow and a bright shock knot, 13CO is tracing the outer (∼1000 au) envelope/pseudo-disc, and C18O is tracing the inner (∼500 au) pseudo-disc. The source size of ∼8.6 au measured in the 873μm image is comparable to the inner Keplerian disc size predicted by the model. A 3D model structure of ISO-OPH 200 suggests that this system is viewed partially through a wide outflow cavity resulting in a direct view of the outflow and a partial view of the envelope/pseudo-disc. We have argued that ISO-OPH 200 has been mis-classified as a Class Flat object due to the unusual orientation. The various signatures of this system, notably, the young ∼616 yr outflow dynamical age and high outflow rate (∼1 × 10−7 M⊙ yr−1), silicate absorption in the 10$\rm{\mu m}$ mid-infrared spectrum, pristine ISM-like dust in the envelope/disc, comparable sizes of the extended envelope and outflow, indicate that ISO-OPH 200 is an early Class 0 stage system formed in a star-like mechanism via gravitational collapse of a very low-mass core.

scholarly journals Classical T Tauri-like Outflow Activity in the Brown Dwarf Mass Regime

2009 ◽  
Vol 5 (H15) ◽  
pp. 754-754
Author(s):  
E. T. Whelan ◽  
T. P. Ray ◽  
F. Bacciotti ◽  
L. Podio ◽  
S. Randich
Keyword(s):  
Brown Dwarf ◽  
T Tauri ◽  
Relative Brightness ◽  
Accretion Rates ◽  
Outflow Rate ◽  
Mass Outflow ◽  
Complete Discussion ◽  
Comprehensive Comparison ◽  
Low Mass ◽  
Measured Mass

Since 2005 we have been analysing the spectra of brown dwarfs (BDs) using the technique of spectro-astrometry and to date have found 5 outflows driven by BDs. Our aim is to obtain an understanding of outflow activity in the BD mass regime and make a comprehensive comparison with low mass protostars, in particular the classical T Tauri stars (CTTSs). Table 1 summarises some results for the sources in our sample. Also see Whelan et al. (2009b) for a complete discussion and comparison with CTTSs. Some noteworthy results include the asymmetry in the ISO-217 bipolar outflow which is revealed in the relative brightness of the two lobes (red-shifted lobe is brighter) and the factor of two difference in radial velocity (the red-shifted lobe is faster). Asymmetries are common in jets from low mass protostars (0.1 Msun to 2 Msun) and the observation of a strong asymmetry at such a low mass supports the idea that BD outflow activity is scaled down from CTTSs. In addition, Whelan et al. (2009a) find a strong contribution to the Hα line emitted by LS-RCrA 1 and evidence of a dust hole in its disk. Using methods previously applied to CTTS Whelan et al. (2009b) estimate the mass outflow rate (Ṁout) for LS-RCrA 1, ISO and ISO-Oph 102 Ṁout to be in the range 10−10 to 10−9 Msun yr−1 which is comparable to measured mass accretion rates.

scholarly journals Bipolar molecular outflow of the very low-mass star Par-Lup3-4

2020 ◽  
Vol 640 ◽  
pp. A13
Author(s):  
A. Santamaría-Miranda ◽  
I. de Gregorio-Monsalvo ◽  
N. Huélamo ◽  
A. L. Plunkett ◽  
Á. Ribas ◽  
...  
Keyword(s):  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
Molecular Gas ◽  
Mass Star ◽  
Low Mass Stars ◽  
Molecular Outflow ◽  
Outflow Rate ◽  
Low Mass ◽  
First Time ◽  
Mass Sources

Context. Very low-mass stars are known to have jets and outflows, which is indicative of a scaled-down version of low-mass star formation. However, only very few outflows in very low-mass sources are well characterized. Aims. We characterize the bipolar molecular outflow of the very low-mass star Par-Lup3-4, a 0.12 M⊙ object known to power an optical jet. Methods. We observed Par-Lup3-4 with ALMA in Bands 6 and 7, detecting both the continuum and CO molecular gas. In particular, we studied three main emission lines: CO(2–1), CO(3–2), and 13CO(3–2). Results. Our observations reveal for the first time the base of a bipolar molecular outflow in a very low-mass star, as well as a stream of material moving perpendicular to the primary outflow of this source. The primary outflow morphology is consistent with the previously determined jet orientation and disk inclination. The outflow mass is 9.5 × 10−7 M⊙, with an outflow rate of 4.3 × 10−9 M⊙ yr−1. A new fitting to the spectral energy distribution suggests that Par-Lup3-4 may be a binary system. Conclusions. We have characterized Par-Lup3-4 in detail, and its properties are consistent with those reported in other very low-mass sources. This source provides further evidence that very low-mass sources form as a scaled-down version of low-mass stars.

scholarly journals ON SOME MOMENT MAPS AND INDUCED HOPF BUNDLES IN THE QUATERNIONIC PROJECTIVE SPACE

2000 ◽  
Vol 11 (07) ◽  
pp. 925-942 ◽  
Author(s):  
LIVIU ORNEA ◽  
PAOLO PICCINNI
Keyword(s):  
Projective Space ◽  
Complex Structure ◽  
Quaternionic Projective Space ◽  
Moment Maps ◽  
Zero Sets ◽  
Stiefel Manifolds ◽  
Hypercomplex Structure ◽  
The Moment ◽  
The One

We describe a diagram containing the zero sets of the moment maps associated to the diagonal U(1) and Sp(1) actions on the quaternionic projective space ℍPn. These sets are related both to focal sets of submanifolds and to Sasakian–Einstein structures on induced Hopf bundles. As an application, we construct a complex structure on the Stiefel manifolds [Formula: see text] and [Formula: see text], the one on the former manifold not being compatible with its known hypercomplex structure.

scholarly journals The near-infrared outflow and cavity of the proto-brown dwarf candidate ISO-Oph 200

2018 ◽  
Vol 610 ◽  
pp. L19 ◽  
Author(s):  
E. T. Whelan ◽  
B. Riaz ◽  
B. Rouzé
Keyword(s):  
Field Study ◽  
Electron Density ◽  
Near Infrared ◽  
Position Angle ◽  
Brown Dwarf ◽  
Protostellar Jets ◽  
Outflow Rate ◽  
Mass Outflow ◽  
Low Mass ◽  
Integral Field

In this Letter a near-infrared integral field study of a proto-brown dwarf candidate is presented. A ~0.′′5 blue-shifted outflow is detected in both H2 and [Fe II] lines at Vsys = (–35 ± 2) km s−1 and Vsys = (–51 ± 5) km s−1 respectively. In addition, slower (~±10 km s−1) H2 emission is detected out to <5.′′4, in the direction of both the blue and red-shifted outflow lobes but along a different position angle to the more compact faster emission. It is argued that the more compact emission is a jet and the extended H2 emission is tracing a cavity. The source extinction is estimated at Av = 18 ± 1 mag and the outflow extinction at Av = 9 ± 0.4 mag. The H2 outflow temperature is calculated to be 1422 ± 255 K and the electron density of the [Fe II] outflow is measured at ~10 000 cm−3. Furthermore, the mass outflow rate is estimated at Ṁout [H2]  = 3.8 × 10−10 M⊙ yr−1 and Ṁout[Fe II] = 1 × 10−8 M⊙ yr−1. Ṁout[Fe II] takes a Fe depletion of ~88% into account. The depletion is investigated using the ratio of the [Fe II] 1.257 μm and [P II] 1.188 μm lines. Using the Paβ and Brγ lines and a range in stellar mass and radius Ṁacc is calculated to be (3–10) × 10−8 M⊙ yr−1. Comparing these rates puts the jet efficiency in line with predictions of magneto-centrifugal models of jet launching in low mass protostars. This is a further case of a brown dwarf outflow exhibiting analogous properties to protostellar jets.

scholarly journals 4d mirror-like dualities

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Chiung Hwang ◽  
Sara Pasquetti ◽  
Matteo Sacchi
Keyword(s):  
Dimensional Reduction ◽  
Moment Maps ◽  
Turn On ◽  
New Strategy ◽  
Real Mass ◽  
The Moment

Abstract We construct a family of 4d$$ \mathcal{N} $$ N = 1 theories that we call $$ {E}_{\rho}^{\sigma } $$ E ρ σ [USp(2N)] which exhibit a novel type of 4d IR duality very reminiscent of the mirror duality enjoyed by the 3d$$ \mathcal{N} $$ N = 4 $$ {T}_{\rho}^{\sigma } $$ T ρ σ [SU(N)] theories. We obtain the $$ {E}_{\rho}^{\sigma } $$ E ρ σ [USp(2N)] theories from the recently introduced E[USp(2N )] theory, by following the RG flow initiated by vevs labelled by partitions ρ and σ for two operators transforming in the antisymmetric representations of the USp(2N) × USp(2N) IR symmetries of the E[USp(2N)] theory. These vevs are the 4d uplift of the ones we turn on for the moment maps of T[SU(N)] to trigger the flow to $$ {T}_{\rho}^{\sigma } $$ T ρ σ [SU(N)]. Indeed the E[USp(2N)] theory, upon dimensional reduction and suitable real mass deformations, reduces to the T[SU(N)] theory. In order to study the RG flows triggered by the vevs we develop a new strategy based on the duality webs of the T[SU(N)] and E[USp(2N)] theories.

scholarly journals FURTHER DEFINING SPECTRAL TYPE “Y” AND EXPLORING THE LOW-MASS END OF THE FIELD BROWN DWARF MASS FUNCTION

2012 ◽  
Vol 753 (2) ◽  
pp. 156 ◽  
Author(s):  
J. Davy Kirkpatrick ◽  
Christopher R. Gelino ◽  
Michael C. Cushing ◽  
Gregory N. Mace ◽  
Roger L. Griffith ◽  
...  
Keyword(s):  
Spectral Type ◽  
Mass Function ◽  
Brown Dwarf ◽  
Low Mass

scholarly journals VLT/SPHERE astrometric confirmation and orbital analysis of the brown dwarf companion HR 2562 B

2018 ◽  
Vol 615 ◽  
pp. A177 ◽  
Author(s):  
A.-L. Maire ◽  
L. Rodet ◽  
C. Lazzoni ◽  
A. Boccaletti ◽  
W. Brandner ◽  
...  
Keyword(s):  
Orbital Motion ◽  
Orbital Plane ◽  
Real Data ◽  
Far Infrared ◽  
Brown Dwarf ◽  
Orbital Parameters ◽  
System A ◽  
Low Mass ◽  
Debris Disk ◽  
Orbital Periods

Context. A low-mass brown dwarf has recently been imaged around HR 2562 (HD 50571), a star hosting a debris disk resolved in the far infrared. Interestingly, the companion location is compatible with an orbit coplanar with the disk and interior to the debris belt. This feature makes the system a valuable laboratory to analyze the formation of substellar companions in a circumstellar disk and potential disk-companion dynamical interactions. Aims. We aim to further characterize the orbital motion of HR 2562 B and its interactions with the host star debris disk. Methods. We performed a monitoring of the system over ~10 months in 2016 and 2017 with the VLT/SPHERE exoplanet imager. Results. We confirm that the companion is comoving with the star and detect for the first time an orbital motion at high significance, with a current orbital motion projected in the plane of the sky of 25 mas (~0.85 au) per year. No orbital curvature is seen in the measurements. An orbital fit of the SPHERE and literature astrometry of the companion without priors on the orbital plane clearly indicates that its orbit is (quasi-)coplanar with the disk. To further constrain the other orbital parameters, we used empirical laws for a companion chaotic zone validated by N-body simulations to test the orbital solutions that are compatible with the estimated disk cavity size. Non-zero eccentricities (>0.15) are allowed for orbital periods shorter than 100 yr, while only moderate eccentricities up to ~0.3 for orbital periods longer than 200 yr are compatible with the disk observations. A comparison of synthetic Herschel images to the real data does not allow us to constrain the upper eccentricity of the companion.

scholarly journals X-Ray Detection of Brown Dwarfs with Chandra

2003 ◽  
Vol 211 ◽  
pp. 447-450 ◽  
Author(s):  
Scott J. Wolk
Keyword(s):  
Brown Dwarfs ◽  
Stellar Clusters ◽  
Brown Dwarf ◽  
Low Mass Stars ◽  
X Ray ◽  
Low Mass ◽  
Vast Range

I review recent observations of brown dwarfs by the Chandra X-ray Observatory. These observations fall in 2 categories, young stellar clusters which contain brown dwarfs and brown dwarf candidates and directed pointings at brown dwarfs and very low mass stars. Surprisingly, there are already over 60 published detections of brown dwarfs by Chandra. A review of the X–ray characteristics shows these objects are subject to flaring and their temperatures and luminosities have a vast range which is related to age.

Deep Near-Infrared Surveys and Young Brown Dwarf Populations in Star-Forming Regions

2003 ◽  
Vol 211 ◽  
pp. 87-90
Author(s):  
M. Tamura ◽  
T. Naoi ◽  
Y. Oasa ◽  
Y. Nakajima ◽  
C. Nagashima ◽  
...  
Keyword(s):  
High Resolution ◽  
Adaptive Optics ◽  
Near Infrared ◽  
Brown Dwarf ◽  
Ir Camera ◽  
Star Forming ◽  
Star Forming Regions ◽  
New Instrument ◽  
Infrared Surveys ◽  
Low Mass

We are currently conducting three kinds of IR surveys of star forming regions (SFRs) in order to seek for very low-mass young stellar populations. First is a deep JHKs-bands (simultaneous) survey with the SIRIUS camera on the IRSF 1.4m or the UH 2.2m telescopes. Second is a very deep JHKs survey with the CISCO IR camera on the Subaru 8.2m telescope. Third is a high resolution companion search around nearby YSOs with the CIAO adaptive optics coronagraph IR camera on the Subaru. In this contribution, we describe our SIRIUS camera and present preliminary results of the ongoing surveys with this new instrument.

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