Neutral hydrogen in the W41 region

Gordon, Courtney P.; Gordon, Kurtiss J.; Jacobson, M. R.

doi:10.1086/154116

Cited by 4 publications

(5 citation statements)

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“…These methods have been employed by Tian et al (2007a) to measure the kinematic distances of the SNR G18.8+0.3 and its associated CO clouds. Gordon et al (1976) first estimated distance of 4.6 -7 kpc for W41 by observations of HI emission and absorption in the W41 region. Tian et al (2007b) revised the distance using an incorrect association with a molecular cloud at about 63 km/s.…”

Section: Introductionmentioning

confidence: 99%

The Distances of SNR W41 and Overlapping H Ii Regions

Leahy

2007

The Astronomical Journal

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New HI images from the VLA Galactic Plane Survey show prominent absorption features associated with the supernovae remnant G23.3-0.3 (SNR W41). We highlight the HI absorption spectra and the 13 CO emission spectra of eight small regions on the face of W41, including four HII regions, three non-thermal emission regions and one unclassified region. The maximum velocity of absorption for W41 is 78±2 km/s and the CO cloud at radial velocity 95±5 km/s is behind W41. Because an extended TeV source, a diffuse X-ray enhancement and a large molecular cloud at radial velocity 77±5 km/s overlap the center of W41, the kinematic distance is 3.9 to 4.5 kpc for W41. For the HII regions, our analysis shows that both G23.42-0.21 and G23.07+0.25 are at the far kinematic distances (∼9.9 kpc and ∼ 10.6 kpc respectively) of their recombination-line velocities (103±0.5 km/s and 89.6±2.1 km/s respectively), G23.07-0.37 is at the near kinematic distance (4.4±0.3 kpc) of its recombination-line velocity (82.7±2.0 km/s), and G23.27-0.27 is probably at the near kinematic distance (4.1±0.3 kpc) of its recombination-line velocity (76.1±0.6 km/s).

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Section: Introductionmentioning

confidence: 99%

The Distances of SNR W41 and Overlapping H Ii Regions

Leahy

2007

The Astronomical Journal

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“…V5668 Sgr is a slow-evolving dust-forming classical nova (Harvey et al 2018; Chomiuk et al 2021b) discovered by J. Seach on 2015 March 15.634 UT, at a distance of kpc (Gordon et al 2021a). It is well-sampled at centimetre radio wavelengths with the VLA and ATCA (Chomiuk et al 2021b), and has near-simultaneous detections in the RACS survey with ASKAP (see Figure 2 top panel left image ).…”

Section: Resultsmentioning

confidence: 99%

“…V1369 Cen was discovered in an eruption on 2013 December 2.69 UT by J. Seach at a distance of kpc (Gordon et al 2021a). It was detected with the ATCA between 2013 December 5 and 2014 May 27 in multi-frequency observations (5.5–34 GHz) by Bannister et al (2014), Chomiuk et al (2021b).…”

Section: Resultsmentioning

confidence: 99%

“…It is characterised as a fast radio classical nova by Chomiuk et al (2021b). Despite multiwavelength studies of the object at near-IR (Mason et al 2021), UV (Shore et al 2014), gamma ray (Cheung et al 2016), and X-ray wavelengths (Gordon et al 2021a), radio observations of V1369 Cen around its thermal maximum are limited. The radio counterpart of V1369 Cen in RACS is offset by 0 ′′ .9 from its optical position.

Figure 3. Hubble Flow model fit to V1369 Cen radio detections.…”

Section: Resultsmentioning

confidence: 99%

“…Radio studies of novae have helped to model the expanding ejecta and its morphology (e.g., Hjellming et al 1979; Weston 2016; Taylor et al 1988), yielding measurements for distances (e.g., V959 Mon; Linford et al 2015), shell masses (e.g., T Pyx; Nelson et al 2014) and kinetic energies (e.g., Nova Aquilae; Snijders et al 1987). Following the discovery of GeV gamma-ray emission from novae (e.g., Abdo et al 2010; Ackermann et al 2014; Gordon et al 2021a; Franckowiak et al 2018), an increasing number are being targeted at radio wavelengths in large-scale (e.g., Chomiuk et al 2021b; Bode, Seaquist, & Evans 1987) and individual follow-up campaigns focused on novae with high optical brightness (e.g., V1500 Cyg; Hjellming et al 1979), gamma-ray observations (e.g., V959 Mon; Chomiuk et al 2014, V1324 Sco; Finzell et al 2018), and recurrent nova status (e.g., U Sco; Chomiuk et al 2021b).…”

Section: Introductionmentioning

confidence: 99%

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Classical novae in the ASKAP pilot surveys

Ashna

Murphy

Kaplan

et al. 2023

Publ. Astron. Soc. Aust.

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We present a systematic search for radio counterparts of novae using the Australian Square Kilometer Array Pathfinder (ASKAP). Our search used the Rapid ASKAP Continuum Survey, which covered the entire sky south of declination $+41^{\circ}$ ( $\sim$ $34000$ square degrees) at a central frequency of 887.5 MHz, the Variables and Slow Transients Pilot Survey, which covered $\sim$ $5000$ square degrees per epoch (887.5 MHz), and other ASKAP pilot surveys, which covered $\sim$ 200–2000 square degrees with 2–12 h integration times. We crossmatched radio sources found in these surveys over a two–year period, from 2019 April to 2021 August, with 440 previously identified optical novae, and found radio counterparts for four novae: V5668 Sgr, V1369 Cen, YZ Ret, and RR Tel. Follow-up observations with the Australian Telescope Compact Array confirm the ejecta thinning across all observed bands with spectral analysis indicative of synchrotron emission in V1369 Cen and YZ Ret. Our light-curve fit with the Hubble Flow model yields a value of $1.65\pm 0.17 \times 10^{-4} \rm \:M_\odot$ for the mass ejected in V1369 Cen. We also derive a peak surface brightness temperature of $250\pm80$ K for YZ Ret. Using Hubble Flow model simulated radio lightcurves for novae, we demonstrate that with a 5 $\sigma$ sensitivity limit of 1.5 mJy in 15-min survey observations, we can detect radio emission up to a distance of 4 kpc if ejecta mass is in the range $10^{-3}\rm \:M_\odot$ , and upto 1 kpc if ejecta mass is in the range $10^{-5}$ – $10^{-3}\rm \:M_\odot$ . Our study highlights ASKAP’s ability to contribute to future radio observations for novae within a distance of 1 kpc hosted on white dwarfs with masses $0.4$ – $1.25\:\rm M_\odot$ , and within a distance of 4 kpc hosted on white dwarfs with masses $0.4$ – $1.0\:\rm M_\odot$ .

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