Front Matter: Volume 9910

Brissenden, Roger; Silva, David R.

doi:10.1117/12.2240598

Cited by 7 publications

References 2 publications

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Detection of Fe and evidence for TiO in the dayside emission spectrum of WASP-33b

Cont

Yan

Reiners

et al. 2021

A&A

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Context. Theoretical studies predict the presence of thermal inversions in the atmosphere of highly irradiated gas giant planets. Recent observations have identified these inversion layers. However, the role of different chemical species in their formation remains unclear. Aims. We search for the signature of the thermal inversion agents TiO and Fe in the dayside emission spectrum of the ultra-hot Jupiter WASP-33b. Methods. The spectra were obtained with CARMENES and HARPS-N, covering different wavelength ranges. Telluric and stellar absorption lines were removed with SYSREM. We cross-correlated the residual spectra with model spectra to retrieve the signals from the planetary atmosphere. Results. We find evidence for TiO at a significance of 4.9σ with CARMENES. The strength of the TiO signal drops close to the secondary eclipse. No TiO signal is found with HARPS-N. An injection-recovery test suggests that the TiO signal is below the detection level at the wavelengths covered by HARPS-N. The emission signature of Fe is detected with both instruments at significance levels of 5.7σ and 4.5σ, respectively. By combining all observations, we obtain a significance level of 7.3σ for Fe. We find the TiO signal at Kp = 248.0−2.5+2.0 km s−1, which is in disagreement with the Fe detection at Kp = 225.0−3.5+4.0 km s−1. The Kp value for Fe is in agreement with prior investigations. The model spectra require different temperature profiles for TiO and Fe to match the observations. We observe a broader line profile for Fe than for TiO. Conclusions. Our results confirm the existence of a temperature inversion layer in the planetary atmosphere. The observed Kp offset and different strengths of broadening in the line profiles suggest the existence of a TiO-depleted hot spot in the planetary atmosphere.

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Detection of Fe and evidence for TiO in the dayside emission spectrum of WASP-33b

Cont

Yan

Reiners

et al. 2021

A&A

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Sub-Chandrasekhar progenitors favoured for type Ia supernovae: Evidence from late-time spectroscopy★.

Flörs

Spyromilio

Taubenberger

et al. 2019

Monthly Notices of the Royal Astronomical Society

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A non-local-thermodynamic-equilibrium (NLTE) level population model of the first and second ionisation stages of iron, nickel and cobalt is used to fit a sample of XShooter optical + near-infrared (NIR) spectra of Type Ia supernovae (SNe Ia). From the ratio of the NIR lines to the optical lines limits can be placed on the temperature and density of the emission region. We find a similar evolution of these parameters across our sample. Using the evolution of the Fe ii 12 570Å to 7 155Å line as a prior in fits of spectra covering only the optical wavelengths we show that the 7200Å feature is fully explained by [Fe ii] and [Ni ii] alone. This approach allows us to determine the abundance of Ni ii/Fe ii for a large sample of 130 optical spectra of 58 SNe Ia with uncertainties small enough to distinguish between Chandrasekhar mass (M Ch ) and sub-Chandrasekhar mass (sub-M Ch ) explosion models. We conclude that the majority (85%) of normal SNe Ia have a Ni/Fe abundance that is in agreement with predictions of sub-M Ch explosion simulations of ∼ Z progenitors. Only a small fraction (11%) of objects in the sample have a Ni/Fe abundance in agreement with M Ch explosion models.

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Temporal and spatial variation of synchrotron X-ray stripes in Tycho’s supernova remnant

Matsuda

Tanaka

Uchida

et al. 2020

Publications of the Astronomical Society of Japan

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The synchrotron X-ray “stripes” discovered in Tycho’s supernova remnant (SNR) have been attracting attention as they may be evidence for proton acceleration up to PeV. We analyzed Chandra data taken in 2003, 2007, 2009, and 2015 for imaging and spectroscopy of the stripes in the southwestern region of the SNR. Comparing images obtained at different epochs, we find that time variability of synchrotron X-rays is not limited to two structures previously reported but is more common in the region. Spectral analysis of nine bright stripes reveals not only their time variabilities but also a strong anti-correlation between the surface brightness and photon indices. The spectra of the nine stripes have photon indices of Γ = 2.1–2.6 and are significantly harder than those of the outer rim of the SNR in the same region with Γ = 2.7–2.9. Based on these findings, we indicate that the magnetic field is substantially amplified, and suggest that particle acceleration through a stochastic process may be at work in the stripes.

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Front Matter: Volume 9910

Cited by 7 publications

References 2 publications

Detection of Fe and evidence for TiO in the dayside emission spectrum of WASP-33b

Detection of Fe and evidence for TiO in the dayside emission spectrum of WASP-33b

Sub-Chandrasekhar progenitors favoured for type Ia supernovae: Evidence from late-time spectroscopy★.

Temporal and spatial variation of synchrotron X-ray stripes in Tycho’s supernova remnant

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