J/A+A/631/A74 POETS luminous YSOs 13 or 22GHz images (Moscadelli+, 2019)
Protostellar Outflows at the EarliesT Stages (POETS).
III. H2O masers tracing disk-winds and jets near luminous YSOs.
Moscadelli L., Sanna A., Goddi C., Krishnan V., Massi F., Bacciotti F.
<Astron. Astrophys. 631, A74 (2019)>
=2019A&A...631A..74M 2019A&A...631A..74M (SIMBAD/NED BibCode)
ADC_Keywords: Masers ; Radio sources
Keywords: ISM: jets and outflows - ISM: molecules - masers -
radio continuum: ISM - techniques: interferometric
Abstract:
Although recent observations and theoretical simulations have pointed
out that accretion disks and jets can be essential for the formation
of stars with a mass of up to at least 20M☉, the processes
regulating mass accretion and ejection are still uncertain.
The goal of the Protostellar Outflows at the EarliesT Stages (POETS)
survey is to image the disk-outflow interface on scales of 10-100au
in a statistically significant sample (36) of luminous young stellar
objects (YSO), targeting both the molecular and ionized components of
the outflows.
The outflow kinematics is studied at milliarcsecond scales through
very long baseline interferometry (VLBI) observations of the 22GHz
water masers, which are ideal test particles to measure the
three-dimensional (3D) motion of shocks owing to the interaction of
winds and jets with ambient gas. We employed the Jansky Very Large
Array (JVLA) at 6, 13, and 22GHz in the Aand B-Array configurations
to determine the spatial structure and the spectral index of the radio
continuum emission, and address its nature.
In about half of the targets, the water masers observed at separation
≤1000au from the YSOs trace either or both of these kinematic
structures: 1) a spatially elongated distribution oriented at close
angle with the direction of collimation of the maser proper motions
(PM), and 2) a linear local standard of rest (LSR) velocity (VLSR)
gradient across the YSO position. The kinematic structure (1) is
readily interpreted in terms of a protostellar jet, as confirmed in
some targets via the comparison with independent observations of the
YSO jets, in thermal (continuum and line) emissions, reported in the
literature. The kinematic structure (2) is interpreted in terms of a
disk-wind (DW) seen almost edge-on on the basis of several pieces of
evidence: first, it is invariably directed perpendicular to the YSO
jet; second, it agrees in orientation and polarity with the VLSR
gradient in thermal emissions (when reported in the literature)
identifying the YSO disk at scales of ≤1000au; third, the PMs of the
masers delineating the VLSR gradients hint at flow motions at a speed
of 10-20km/s directed at large angles with the disk midplane. In
the remaining targets, the maser PMs are not collimated but rather
tend to align along two almost perpendicular directions. To explain
this peculiar PM distribution, and in light of the observational bias
strongly favoring masers moving close to the plane of sky, we propose
that, in these sources, the maser emission could originate in DW-jet
systems slightly inclined (≤30°) with respect to edge-on.
Magneto-centrifugally driven DWs could in general account for the
observed velocity patterns of water masers.
Description:
We performed continuum JVLA observations at 13GHz (using the A-array
configuration) and at 22GHz (B-Array) of a sample of luminous YSOs.
For each target, we provide either the 13 or 22GHz JVLA calibrated
map.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
targets.dat 34 27 Target list
list.dat 148 27 List of fits images
fits/* . 27 Individual fits images
--------------------------------------------------------------------------------
Byte-by-byte Description of file: targets.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Name Target name
15- 16 I2 h RAh Right ascension (J2000)
18- 19 I2 min RAm Right ascension (J2000)
21- 24 F4.1 s RAs Right ascension (J2000)
26 A1 --- DE- Declination sign (J2000)
27- 28 I2 deg DEd Declination (J2000)
30- 31 I2 arcmin DEm Declination (J2000)
33- 34 I2 arcsec DEs Declination (J2000)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Name Target name
14- 22 F9.5 deg RAdeg Right Ascension of center (J2000)
23- 31 F9.5 deg DEdeg Declination of center (J2000)
33- 36 I4 --- Nx Number of pixels along X-axis
38- 41 I4 --- Ny Number of pixels along Y-axis
43- 63 A21 "datime" Obs.date Observation date
65- 66 I2 GHz Freq Observed frequency
68- 73 I6 Kibyte size Size of FITS file
75-121 A47 --- FileName Name of FITS file, in subdirectory fits
123-148 A26 --- Title Title of the FITS file
--------------------------------------------------------------------------------
Acknowledgements:
Luca Moscadelli, mosca(at)arcetri.astro.it
References:
Sanna et al., Paper I 2018A&A...619A.107S 2018A&A...619A.107S
Sanna et al., Paper II 2019A&A...623L...3S 2019A&A...623L...3S
(End) Luca Moscadelli [Arcetri], Patricia Vannier [CDS] 01-Oct-2019