VLBI Astrometry of AGB Variables with VERA — A Semiregular Variable S Crateris—

Nakagawa, Akiharu; Tsushima, Miyuki; Ando, Kazuma; Bushimata, Takeshi; Choi, Yoon Kyung; Hirota, Tomoya; Honma, Mareki; Imai, Hiroshi; Iwadate, Kenzaburo; Jike, Takaaki; Kameno, Seiji; Kameya, Osamu; Kamohara, Ryuichi; Kan-ya, Yukitoshi; Kawaguchi, Noriyuki; Kijima, Minoru; Kim, Mi Kyoung; Kobayashi, Hideyuki; Kuji, Seisuke; Kurayama, Tomoharu; Maeda, Tamaki; Manabe, S.; Maruyama, Kenta; Matsui, Makoto; Matsumoto, Naoko; Miyaji, Takeshi; Nagayama, Tomonori; Nakamura, Kayoko; Nyu, Daisuke; Oh, Chung Sik; Omodaká, Toshihiro; Oyama, Tomoaki; Pradel, Nicolas; Sakai, Satoshi; Sasao, Tetsuo; Sato, Katsuhisa; Sato, M.; Shibata, Katsunori M.; Suda, Hiroshi; Tamura, Yoshiaki; Ueda, Kousuke; Ueno, Yuji; Yamashita, K.

doi:10.1093/pasj/60.5.1013

Cited by 39 publications

(13 citation statements)

References 24 publications

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“…As reviewed by Whitelock et al (2008), their results are consistent with the PLR of the LMC Miras within their uncertainties, which are still not small enough to draw strong conclusions about the zero-point or the population effect. VERA, a Japanese very long baseline interferometry (VLBI) project, is one of the most promising projects for calibrating the PLR of Miras in the Galaxy (Nakagawa et al 2008(Nakagawa et al , 2009). However, the use of radio parallaxes is constrained by the small numbers of Miras with maser emission in the short-period range, say P ≤ 300 d. In our method for deriving the distance and the extinction, we make use of short-period Miras to avoid the effects of circumstellar extinction and/or hot-bottom burning.…”

Section: Future Prospectsmentioning

confidence: 99%

A near-infrared survey of Miras and the distance to the Galactic Centre

Matsunaga

Kawadu

Nishiyama

et al. 2009

Monthly Notices of the Royal Astronomical Society

119

163

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We report the results of a near-infrared survey for long-period variables in a field of view of 20 arcmin by 30 arcmin towards the Galactic Centre (GC). We have detected 1364 variables, of which 348 are identified with those reported in Glass et al. (2001). We present a catalogue and photometric measurements for the detected variables and discuss their nature. We also establish a method for the simultaneous estimation of distances and extinctions using the period-luminosity relations for the JHK s bands. Our method is applicable to Miras with periods in the range 100 -350 d and mean magnitudes available in two or more filter bands. While J-band means are often unavailable for our objects because of the large extinction, we estimated distances and extinctions for 143 Miras whose H-and K s -band mean magnitudes are obtained. We find that most are located at the same distance to within our accuracy. Assuming that the barycentre of these Miras corresponds to the GC, we estimate its distance modulus to be 14.58 ± 0.02 (stat .) ± 0.11 (syst .) mag, corresponding to 8.24 ± 0.08 (stat .) ± 0.42 (syst .) kpc. We have assumed the distance modulus to the LMC to be 18.45 mag, and the uncertainty in this quantity is included in the systematic error above. We also discuss the large and highly variable extinction. Its value ranges from 1.5 mag to larger than 4 mag in A Ks except towards the thicker dark nebulae and it varies in a complicated way with the line of sight. We have identified mid-infrared counterparts in the Spitzer/IRAC catalogue of Ramírez et al. (2008) for most of our variables and find that they follow rather narrow period-luminosity relations in the 3.6 to 8.0 µm wavelength range.

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Section: Future Prospectsmentioning

confidence: 99%

A near-infrared survey of Miras and the distance to the Galactic Centre

Matsunaga

Kawadu

Nishiyama

et al. 2009

Monthly Notices of the Royal Astronomical Society

119

163

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“…The position error of each measurement was estimated from the root sum square of the following three error factors: (1) the airmass effect σ A , (2) the errors in station positions σ S , and (3) the quality of images σ I . After the calibration of airmass effect in the delay tracking model, there still remains an uncertainty of about 3 cm in the zenith direction (Nakagawa et al 2008;Honma et al 2007). Therefore, the error from factor (1) is estimated to be σ A =80-110 µas (Nakagawa et al 2008;Honma et al 2007).…”

Section: Uncertainty Of Each Epochmentioning

confidence: 99%

“…After the calibration of airmass effect in the delay tracking model, there still remains an uncertainty of about 3 cm in the zenith direction (Nakagawa et al 2008;Honma et al 2007). Therefore, the error from factor (1) is estimated to be σ A =80-110 µas (Nakagawa et al 2008;Honma et al 2007). Station positions are determined to be an accuracy of ∼3 mm based on geodetic observation (Nakagawa et al 2008;Honma et al 2007), the error from factor (2) was estimated to be σ S = 8µas.…”

Section: Uncertainty Of Each Epochmentioning

confidence: 99%

“…Therefore, the error from factor (1) is estimated to be σ A =80-110 µas (Nakagawa et al 2008;Honma et al 2007). Station positions are determined to be an accuracy of ∼3 mm based on geodetic observation (Nakagawa et al 2008;Honma et al 2007), the error from factor (2) was estimated to be σ S = 8µas. We estimate the error from factor (3) from σ I = θ b /SNR, where θ b is a root sum square of major and minor axes of the synthesized beams and SNR is a signal-to-noise ratio in the phase referenced image of the maser.…”

Section: Uncertainty Of Each Epochmentioning

confidence: 99%

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VLBI Astrometry of the Semiregular Variable RX Bootis

Kamezaki

Nakagawa

Omodaká

et al. 2012

Publications of the Astronomical Society of Japan

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We present distance measurement of the semiregular variable RX Bootis (RX Boo) with its annual parallax. Using the unique dual-beam system of the VLBI Exploration of Radio Astrometry (VERA) telescope, we conducted astrometric observations of a water maser spot accompanying RX Boo referred to the quasar J1419+2706 separated by 1 • .69 from RX Boo. We have measured the annual parallax of RX Boo to be 7.31 ± 0.50 mas, corresponding to a distance of 136 +10 −9 pc, from the one-year monitoring observation data of one maser spot at V LSR = 3.2 km s −1 . The distance itself is consistent with the one obtained with Hipparcos. The distance uncertainty is reduced by a factor of two, allowing us to determine the stellar properties more accurately. Using our distance, we discuss the location of RX Boo in various sequences of Period-Luminosity (PL) relations. We found RX Boo is located in the Mira sequence of PL relation. In addition, we calculated the radius of photosphere and the mass limitation of RX Boo and discussed its evolutionary status.

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“…We have evaluated three error sources, i.e. thermal noise in the phase-referenced images, errors of baseline vectors and atmo-spheric phase fluctuations, in the same way as Nakagawa et al (2008). The atmospheric zenith delay residuals (∼0.7 cm on average) are determined by the image-optimizing method (Honma et al 2007;Honma, Tamura & Reid 2008).…”

Section: Single-dish Observationsmentioning

confidence: 99%

Intermittent maser flare around the high-mass young stellar object G353.273+0.641 - I. Data and overview

Motogi¹,

Saito²,

Honma³

et al. 2011

Monthly Notices of the Royal Astronomical Society

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We have performed very long baseline interferometry (VLBI) and single‐dish monitoring of 22‐GHz H2O maser emission from the high‐mass young stellar object G353.273+0.641 with the VLBI Exploration of Radio Astrometry (VERA) and the Tomakamai 11‐m radio telescope. Two maser flares have been detected, separated by almost two years. Frequent VLBI monitoring has revealed that the flare activity has been accompanied by structural change of the prominent shock front traced by H2O maser alignments. We have detected only blueshifted emission and all maser features have been distributed within a very small area of 200 × 200 au2, in spite of a wide velocity range (>100 km s−1). The light curve shows notably intermittent variation and suggests that the H2O masers in G353.273+0.641 are excited by an episodic radio jet. The time‐scale of ∼2 yr and characteristic velocity of ∼500 km s−1 also support this interpretation. Two isolated velocity components, C50 (−53 ± 7 km s−1) and C70 (−73 ± 7 km s−1), have shown synchronized linear acceleration of the flux‐weighted values (∼ −5 km s−1 yr−1) during the flare phase. This can be converted to the lower‐limit momentum rate of 1.1 × 10−3 M⊙ km s−1 yr−1. The maser properties are quite similar to those of IRAS 20126+4104 especially. This corroborates the previous suggestion that G353.273+0.641 is a candidate high‐mass protostellar object. The possible pole‐on geometry of the disc–jet system may be suitable for direct imaging of the accretion disc in this case.

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VLBI Astrometry of AGB Variables with VERA — A Semiregular Variable S Crateris—

Cited by 39 publications

References 24 publications

A near-infrared survey of Miras and the distance to the Galactic Centre

A near-infrared survey of Miras and the distance to the Galactic Centre

VLBI Astrometry of the Semiregular Variable RX Bootis

Intermittent maser flare around the high-mass young stellar object G353.273+0.641 - I. Data and overview

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