GMRT detections of low-mass young stars at 323 and 608 MHz

Ainsworth, Rachael; Scaife, Anna M. M.; Green, David A.; Coughlan, Colm P.; Ray, T. P.

doi:10.1093/mnras/stw708

Cited by 9 publications

(30 citation statements)

References 79 publications

(84 reference statements)

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“…Estimates of this kind are, of course, very uncertain given the absence of any exoplanet detections at radio wavelengths. GMRT observations at 323 and 608 MHz of other young stellar objects in Taurus indicate mJy flux levels that are consistent with free-free emission rather than a coherent emission process (Ainsworth et al 2016).…”

Section: Analysis and Discussionmentioning

confidence: 74%

Variable Radio Emission From the Young Stellar Host of a Hot Jupiter

Bower¹,

Loinard

Dzib

et al. 2016

ApJ

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We report the discovery of variable radio emission associated with the T Tauri star, V830 Tau, which was recently shown to host a hot Jupiter companion. Very Large Array observations at a frequency of 6 GHz reveal a detection on 01 May 2011 with a flux density 919 ± 26 µJy, along with nondetections in two other epochs at < 66 and < 150 µJy. Additionally, Very Long Baseline Array observations include one detection and one non-detection at comparable sensitivity, demonstrating that the emission is nonthermal in origin. The emission is consistent with the gyro-synchrotron or synchrotron mechanism from a region with a magnetic field are not able to place any constraint on the relationship between the radio emission and the rotational or orbital properties of V830 Tau. This is the first detection of radio emission from a non-degenerate star known to host an exoplanet.

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Section: Analysis and Discussionmentioning

confidence: 74%

Variable Radio Emission From the Young Stellar Host of a Hot Jupiter

Bower¹,

Loinard

Dzib

et al. 2016

ApJ

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“…The recent GMRT observations of TTau at 323 and 608 MHz by Ainsworth et al (2016) did not resolve the separate components of the YSO, but detected an extended source with a 323-608 MHz spectral index of a = GMRT  0.11 0.14, consistent with (partially) optically thin free-free emission. These results are consistent with the extended freefree component of the emission from the TTauSb outflow (Loinard et al 2007a), which is expected to dominate on large scales (several hundred au).…”

Section: Introductionmentioning

confidence: 86%

“…These results are consistent with the extended freefree component of the emission from the TTauSb outflow (Loinard et al 2007a), which is expected to dominate on large scales (several hundred au). Based on their modeling from 323 MHz to ∼1 THz, Ainsworth et al (2016) estimated that the frequency of the turnover in the free-free spectrum of this emission is ∼200 MHz, suggesting that LOFAR observations Table 2). The (blue) dotted lines show the measurements for TTauN, the (red) dashed lines show the measurements for TTauS and the (black) solid lines shows the combined, total measurement of the (T Tau N+S) system.…”

Section: Introductionmentioning

confidence: 98%

“…However, with their free-free spectra expected to turn over at low frequencies as the emitting medium transitions from optically thin to thick (Scaife 2013), the study of YSOs at low frequencies offers a promising window into the physical parameters of their jets. Recent work by Ainsworth et al (2014Ainsworth et al ( , 2016 has used the Giant Metrewave Radio Telescope (GMRT) to begin studying YSOs at very low radio frequencies (323-608 MHz) and shows the feasibility of observing YSOs with interferometers such as the Low Frequency Array (LOFAR) and, ultimately, the Square Kilometre Array. Ainsworth et al (2016) discussed the importance of investigating the radio emission from young stars at low radio frequencies.…”

Section: Introductionmentioning

confidence: 99%

“…Recent work by Ainsworth et al (2014Ainsworth et al ( , 2016 has used the Giant Metrewave Radio Telescope (GMRT) to begin studying YSOs at very low radio frequencies (323-608 MHz) and shows the feasibility of observing YSOs with interferometers such as the Low Frequency Array (LOFAR) and, ultimately, the Square Kilometre Array. Ainsworth et al (2016) discussed the importance of investigating the radio emission from young stars at low radio frequencies. Physical properties of the ionized plasma, such as the electron density, ionized gas mass, and emission measure, can be well constrained once the low-frequency turnover (between optically thin and thick behavior) in the free-free spectrum has been identified.…”

Section: Introductionmentioning

confidence: 99%

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A LOFAR DETECTION OF THE LOW-MASS YOUNG STAR T TAU AT 149 MHz

Coughlan

Ainsworth

Eislöffel

et al. 2017

ApJ

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Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. ABSTRACTRadio observations of young stellar objects (YSOs) enable the study of ionized plasma outflows from young protostars via their free-free radiation. Previous studies of the low-mass young system TTau have used radio observations to model the spectrum and estimate important physical properties of the associated ionized plasma (local electron density, ionized gas content, and emission measure). However, without an indication of the low-frequency turnover in the free-free spectrum, these properties remain difficult to constrain. This paper presents the detection of TTau at 149 MHz with the Low Frequency Array (LOFAR)-the first time a YSO has been observed at such low frequencies. The recovered total flux indicates that the free-free spectrum may be turning over near 149 MHz. The spectral energy distribution is fitted and yields improved constraints on local electron density ( 7.2 2.1 10 3 ( ) cm −3 ), ionized gas mass ( ´- M 1.0 1.8 10 6 ( ) ), and emission measure ( 1.67 0.14 10 5 ( ) pc cm −6 ).

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Radio observations of evaporating objects in the Cygnus OB2 region

Isequilla

Fernández-López

Benaglia

et al. 2019

A&A

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We present observations of the Cygnus OB2 region obtained with the Giant Metrewave Radio Telescope (GMRT) at the frequencies of 325 MHz and 610 MHz. In this contribution we focus on the study of proplyd-like objects (also known as free-floating Evaporating Gas Globules or frEGGs) that typically show an extended cometary morphology. We identify eight objects previously studied at other wavelengths and derive their physical properties by obtaining their optical depth at radio-wavelengths. Using their geometry and the photoionization rate needed to produce their radio-continuum emission, we find that these sources are possibly ionized by a contribution of the stars Cyg OB2 #9 and Cyg OB2 #22. Spectral index maps of the eight frEGGs were constructed, showing a flat spectrum in radio frequencies in general. We interpret these as produced by optically-thin ionized gas, although it is possible that a combination of thermal emission, not necessarily optically thin, produced by a diffuse gas component and the instrument response (which detects more diffuse emission at low frequencies) can artificially generate negative spectral indices. In particular, for the case of the Tadpole we suggest that the observed emission is not of non-thermal origin despite the presence of regions with negative spectral indices in our maps.

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GMRT detections of low-mass young stars at 323 and 608 MHz

Cited by 9 publications

References 79 publications

Variable Radio Emission From the Young Stellar Host of a Hot Jupiter

Variable Radio Emission From the Young Stellar Host of a Hot Jupiter

A LOFAR DETECTION OF THE LOW-MASS YOUNG STAR T TAU AT 149 MHz

Radio observations of evaporating objects in the Cygnus OB2 region

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