J/A+A/708/A299 YSOs in Orion VLBA observations (Dzib+, 2026)
Dynamical masses of YSOs with the VLBA: DYNAMO VLBA.
Trigonometric parallaxes and proper motions of YSOs in Orion.
Dzib S.A., Ordonez-Toro J., Loinard L., Kounkel M., Ortiz-Leon G.,
Galli P.A.B., Rodriguez L.F., Mioduszewski A.J., Masque J.M., O'Kelly E.,
Forbrich J., Moo-Herrera K.
<Astron. Astrophys. 708, A299 (2026)>
=2026A&A...708A.299D 2026A&A...708A.299D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, pre-main sequence ; Interferometry ; Radio sources
Keywords: astrometry - parallaxes - proper motions - stars: activity -
stars: distances - stars: pre-main sequence
Abstract:
We present results from a multi-epoch Very Long Baseline Array (VLBA)
survey of compact radio sources in the Orion complex, conducted within
both the DYNAMO-VLBA and the GOBELINS projects. Our observations
detected 216 compact radio sources, of which 58 yielded reliable
multi-epoch astrometric solutions. For these sources, we derived
trigonometric parallaxes and proper motions with typical precisions of
about 0.05mas and 0.10mas/yr, respectively. The measured parallaxes
range between 2.26 and 2.65mas, corresponding to distances of
380-440pc, and delineate the depth of the Orion star-forming
complex. We determine mean distances of 405±16pc for NGC 2068,
403±5pc for NGC 2024, 407±12pc for the sigma Orionis region,
388.5±1.7pc for the Orion Nebula Cluster (ONC), and 438±12pc for
L1641. A comparison with Gaia DR3 astrometry for 28 common sources
reveals negligible mean parallax offsets
(Δϖ=-0.02±0.01mas) and small systematic differences in
proper motions (∼0.07mas/yr), likely due to residual rotation of the
Gaia reference frame. Our results demonstrate the capability of
high-precision radio astrometry to map embedded stellar populations
and to provide an independent calibration of the Gaia reference system
in obscured regions.
Description:
table5.dat contains individual-epoch VLBA positions and flux
densities for young stellar objects in the Orion region.
Right ascension and declination are in the ICRS reference frame (J2000
equinox).
Quoted positional uncertainties correspond to formal Gaussian fitting
errors and do not include systematic calibration errors. Flux
densities are measured from image-plane Gaussian fits and corrected by
the primary beam attenuation.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 144 748 Properties of detected radio sources
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 28 A28 --- Name Source name (adopted)
32- 42 A11 --- RadioName Internal identifier
45- 53 A9 --- Project VLBA project code
56- 65 F10.2 d JD Mean Julian Date of observation
68- 69 I2 h RAh Right ascension (J2000)
71- 72 I2 min RAm Right ascension (J2000)
74- 82 F9.6 s RAs Right ascension (J2000)
85- 92 F8.6 s e_RAs Uncertainty in right ascension (1)
96 A1 --- DE- Declination sign (J2000)
97- 98 I2 deg DEd Declination (J2000)
100-101 I2 arcmin DEm Declination (J2000)
103-110 F8.5 arcsec DEs Declination (J2000)
113-119 F7.5 arcsec e_DEs Uncertainty in declination (1)
122-127 I6 uJy Flux Flux density at 5GHz
129-133 I5 uJy e_Flux Flux density uncertainty
135-144 A10 --- MPC Main phase-referencing calibrator
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Note (1): Zero uncertainty values indicate uncertainties below the rounding
precision of the table.
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Acknowledgements:
Sergio A. Dzib, sdzib(at)mpifr-bonn.mpg.de
(End) Patricia Vannier [CDS] 26-Feb-2026