DISTANCE AND PROPER MOTION MEASUREMENT OF THE RED SUPERGIANT, S PERSEI, WITH VLBI H<sub>2</sub>O MASER ASTROMETRY

Asaki, Y.; Deguchi, Shuji; Imai, Hiroshi; Hachisuka, Kazuya; Miyoshi, Makoto; Honma, Mareki

doi:10.1088/0004-637x/721/1/267

Cited by 53 publications

(43 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The fourth to seventh columns list distance, proper motion eastward and northward and LSR velocity of red hypergiant or cluster. Parameters for NML Cyg are from this paper; parameters for VY CMa are from Zhang et al (2012), except that V LSR is from Menten et al (2006); Parameters for S Per are from Asaki et al (2010). Parameters for clusters are from Kharchenko et al (2005), except that V LSR of Cyg OB2 is from Kiminki et al (2007Kiminki et al ( , 2008.…”

Section: Discussionmentioning

confidence: 99%

The distance and size of the red hypergiant NML Cygni from VLBA and VLA astrometry

Zhang¹,

Reid²,

Menten³

et al. 2012

A&A

View full text Add to dashboard Cite

Context. The red hypergiant NML Cyg has been assumed to be at part of the Cyg OB2 association, although its distance has never been measured directly. A reliable distance is crucial to study the properties of this prominent star. For example, its luminosity, and hence its position on the H-R diagram, is critical information to determine its evolutionary status. In addition, a detection of the radio photosphere would be complementary to other methods of determining the stellar size. Aims. We aim to understand the characteristics of NML Cyg with direct measurements of its absolute position, distance, kinematics, and size. Methods. We observe circumstellar 22 GHz H 2 O and 43 GHz SiO masers with the Very Long Baseline Array to determine the parallax and proper motion of NML Cyg. We observe continuum emission at 43 GHz from the radio photosphere of NML Cyg with the Very Large Array. Results. We measure the annual parallax of NML Cyg to be 0.620 ± 0.047 mas, corresponding to a distance of 1.61 +0.13 −0.11 kpc. The measured proper motion of NML Cyg is μ x = −1.55 ± 0.42 mas yr −1 eastward and μ y = −4.59 ± 0.41 mas yr −1 northward. Both the distance and proper motion are consistent with that of Cyg OB2, within their joint uncertainty, confirming their association. Taking into consideration molecular absorption signatures seen toward NML Cyg, we suggest that NML Cyg lies on the far side of the Cyg OB2 association. The stellar luminosity revised with our distance brings NML Cyg significantly below the empirical luminosity limit for a red supergiant. We partially resolve the radio photosphere of NML Cyg at 43 GHz and find its diameter is about 44 mas, suggesting an optical stellar diameter of 22 mas, if the size of radio photosphere is 2 times the optical photosphere. Based on the position of circumstellar SiO masers relative to the radio photosphere, we estimate the absolute position of NML Cyg at epoch 2008.868 to be α J2000 = 20 h 46 m 25. s 5382 ± 0. s 0010, δ J2000 = 40 • 06 59. 379 ± 0. 015. The peculiar motions of NML Cyg, the average of stars in Cyg OB2, and four other star-forming regions rules out that an expanding "Strömgren sphere" centered on Cyg OB2 is responsible for the kinematics of the Cygnus X region.

show abstract

Section: Discussionmentioning

confidence: 99%

The distance and size of the red hypergiant NML Cygni from VLBA and VLA astrometry

Zhang¹,

Reid²,

Menten³

et al. 2012

A&A

View full text Add to dashboard Cite

show abstract

“…In contrast to Reid et al (2009), McMillan & Binney (2010 show that it is fairly justified to adopt their corresponding circular velocity components as probes for the Galactic rotation curve when taking the Schönrich et al values for the peculiar motion of the Sun. Following this argument, parallaxes, proper motions, and heliocentric radial velocities for 30 maser sources have been compiled from the literature (Sandstrom et al 2007;Hirota et al 2008a,b;Reid et al 2009;Rygl et al 2010;Sato et al 2010;Asaki et al 2010;Niinuma et al 2011;Honma et al 2011). To account for the virial motion of the masers with respect to their high-mass star-forming regions, a constant uncertainty of 7 km s −1 (see Reid et al 2009) is added in quadrature to the measurement errors when computing circular velocities.…”

Section: Rotation Curvementioning

confidence: 99%

Milky Way mass models for orbit calculations

Irrgang

Wilcox

Tucker

et al. 2013

A&A

226

339

View full text Add to dashboard Cite

Context. Studying the trajectories of objects like stars, globular clusters, or satellite galaxies in the Milky Way allows the dark matter halo to be traced but requires reliable models of its gravitational potential. Aims. Realistic, yet simple and fully analytical, models have already been presented in the past. However, improved, as well as new, observational constraints have become available in the meantime, calling for a recalibration of the respective model parameters. Methods. Three widely used model potentials are revisited. By a simultaneous least-squares fit to the observed rotation curve, in-plane proper motion of Sgr A*, local mass/surface density, and the velocity dispersion in Baade's window, parameters of the potentials are brought up-to-date. The mass at large radii -in particular, that of the dark matter halo -is hereby constrained by requiring that the most extreme known halo, blue horizontal-branch star has to be bound to the Milky Way. Results. The Galactic mass models are tuned to yield a very good match to recent observations. The mass of the dark matter halo is -within the limitations of the applied models -estimated in a fully consistent way. As a first application, the trajectory of the hypervelocity star HE 0437-5439 is investigated again to check its suggested origin in the Large Magellanic Cloud (LMC). Conclusions. Despite their simplicity, the presented Milky Way mass models are very able to reproduce all observational constraints. Their analytical and simple form makes them ideally suited for fast and accurate orbit calculations. The LMC cannot be ruled out as HE 0437-5439's birthplace.

show abstract

“…expanding outflows) of maser spots (e.g. Imai et al, 2000;Asaki et al, 2010). However, this suggests that a large enough number of spot motions should be measured over many years, and that the motions are often too complicated to be fitted by a simple kinematic model.…”

Section: Effects Of the Internal Motions In S269 On The Galactic Dynamentioning

confidence: 99%

Analysis of H2O masers in Sharpless 269 using VERA archival data—Effect of maser structures on astrometric accuracy

et al. 2012

View full text Add to dashboard Cite

Astrometry using H 2 O maser sources in star forming regions is expected to be a powerful tool to study the structures and dynamics of our Galaxy. Honma et al. (2007) (hereafter H2007) claimed that the annual parallax of Sharpless 269 is determined within an error of 0.008 milliarcsec (mas), concluding that S269 is located at 5.3 kpc ± 0.2 kpc from the sun, and its galactrocetnric distance is R = 13.1 kpc. From the proper motion, they claimed that the galacto-centric rotational velocity of S269 is equal to that of the sun within a 3% error. This small error, however, is hardly understood when taking into account the results of other observations and theoretical studies of galactic dynamics. We here reanalyzed the VERA archival data using the self calibration method (hybrid mapping), and found that clusters of maser features of S269 are distributed in much wider area than that investigated in H2007. We confirmed that, if we make a narrow region image without considering the presence of multiple maser spots, and only the phase calibration is applied, we can reproduce the same maser structures in a maser feature investigated in H2007. The distribution extent of maser spots in the feature differs 0.2 mas from east to west between our results and H2007. Moreover, we found that change of relative positions of maser spots in the cluster reaches 0.1 mas or larger between observational epochs. This suggests that if one simply assumes the time-dependent, widely distributed maser sources as a stable single point source, it could cause errors of up to 0.1 mas in the annual parallax of S269. Taking into account the internal motions of maser spot clusters, the proper motion of S269 cannot be determined precisely. We estimated that the peculiar motion of S269 with respect to a Galactic circular rotation is ∼ 20 km s −1 . These results imply that the observed kinematics of maser emissions in S269 cannot give a strong constraint on dynamics of the outer part of the Galaxy, in contrast to the claim by H2007.

show abstract

DISTANCE AND PROPER MOTION MEASUREMENT OF THE RED SUPERGIANT, S PERSEI, WITH VLBI H₂O MASER ASTROMETRY

Cited by 53 publications

References 40 publications

The distance and size of the red hypergiant NML Cygni from VLBA and VLA astrometry

The distance and size of the red hypergiant NML Cygni from VLBA and VLA astrometry

Milky Way mass models for orbit calculations

Analysis of H2O masers in Sharpless 269 using VERA archival data—Effect of maser structures on astrometric accuracy

Contact Info

Product

Resources

About

DISTANCE AND PROPER MOTION MEASUREMENT OF THE RED SUPERGIANT, S PERSEI, WITH VLBI H2O MASER ASTROMETRY

Cited by 53 publications

References 40 publications

The distance and size of the red hypergiant NML Cygni from VLBA and VLA astrometry

The distance and size of the red hypergiant NML Cygni from VLBA and VLA astrometry

Milky Way mass models for orbit calculations

Analysis of H2O masers in Sharpless 269 using VERA archival data—Effect of maser structures on astrometric accuracy

Contact Info

Product

Resources

About

DISTANCE AND PROPER MOTION MEASUREMENT OF THE RED SUPERGIANT, S PERSEI, WITH VLBI H₂O MASER ASTROMETRY