The High-resolution Soft X-Ray Spectrum of Nova Delphini 2013

Milla, Johon; Paerels, F.

doi:10.3847/1538-4357/aca966

Cited by 3 publications

(3 citation statements)

References 19 publications

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“…Thus, the main absorption feature of the X-ray spectra is consistent with our wind model. The effective temperature of the WD photosphere is about T ph = 3 × 10 5 K during days 88 to 115, much lower than the value of Milla & Paerels (2023). It should be noted that Nelson et al (2013) reported a temperature of kT ∼ 27 eV (T ∼ 3.1 × 10 5 K) for the Chandra X-ray spectrum of V339 Del on day 88, which is consistent with our 1.25 M ☉ WD (Ne2) model.…”

Section: Supersoft X-ray Light Curvesupporting

confidence: 84%

A Multiwavelength Light-curve Model of the Classical Nova V339 Del: A Mechanism for the Coexistence of Dust Dip and Supersoft X-Rays

Hachisu,

Kato,

Matsumoto

2024

ApJ

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The classical nova V339 Del 2013 is characterized by a 1.5 mag dip of the V light curve owing to a dust shell formation, with which soft X-ray emissions coexist. We present a Strömgren y-band light curve, which represents continuum emission, not influenced by strong [O iii] emission lines. The y light curve monotonically decreases in marked contrast to the V light curve that shows a 1.5 mag dip. We propose a multiwavelength light-curve model that reproduces the y and V light curves as well as the gamma-ray and X-ray light curves. In our model, a strong shock arises far outside the photosphere after optical maximum, because later ejected matter collides with earlier ejected gas. Our shocked shell model explains optical emission lines, Hα, hard X-ray, and gamma-ray fluxes. A dust shell forms behind the shock that suppresses [O iii]. This low flux of [O iii] shapes a 1.5 mag drop in the V light curve. Then, the V flux recovers with an increasing contribution from [O iii] lines, while the y flux does not. However, the optical depth of the dust shell is too small to absorb the photospheric (X-ray) emission of the white dwarf. This is the reason that a dust shell and soft X-ray radiation coexist. We determined the white dwarf mass to be M WD = 1.25 ± 0.05 M ☉ and the distance modulus in the V band to be (m − M) V = 12.2 ± 0.2; the distance is d = 2.1 ± 0.2 kpc for the reddening of E(B − V) = 0.18.

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Section: Supersoft X-ray Light Curvesupporting

confidence: 84%

A Multiwavelength Light-curve Model of the Classical Nova V339 Del: A Mechanism for the Coexistence of Dust Dip and Supersoft X-Rays

Hachisu,

Kato,

Matsumoto

2024

ApJ

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“…Since the X-rays started to rise ≈20 days earlier, by day 77 it could have already reached ∼2.5 × 10 14 cm. Interestingly, Nova Delphini 2013 was also observed with gratings late (days 87 and 114 there), featuring blueshifted C and N lines, but in absorption with the SSS as a back-lighter (Milla & Paerels 2023). The fast velocities at these late times led those authors to explain the absorption by a thin shell ejected early, as well, but now 10 15 cm away from the center.…”

Section: Comparing the Two Epochs: Evidence For A Standingmentioning

confidence: 95%

Mixing of Hot Shocked Plasma with Cold Gas in Nova YZ Ret 2020

Mitrani,

Behar,

Drake

et al. 2024

ApJ

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The origin of bright X-ray emission lines that appear late in a nova eruption remains largely a puzzle. We present two high-resolution X-ray grating spectra of the classical nova YZ Ret, observed 77 and 115 days post-eruption, using XMM-Newton and Chandra, respectively. Both spectra feature resolved emission lines blueshifted by v = –1500 km s−1 and broadened by σ v = 500 km s−1. The two spectra are well described by a collisionally ionized plasma of kT ∼ 70 eV that dimmed by a factor of ∼40 between the two exposures. The spectra also show narrow radiative recombination continua (RRCs) of C+4, C+5, and N+5, indicating the interaction of the hot ionized plasma with cold electrons of kT ∼ 2 eV. The high-n Rydberg series of C+4 is anomalously bright, allowing us to measure the electron density through continuum lowering, which is in agreement with the He-like N+5 density diagnostic of n e = (1.7 ± 0.4) × 1011 cm−3. The high population of these high-n levels constitutes the best evidence to date of charge exchange (CX) with neutral H in an astrophysical ionized plasma. The remarkable fact that the velocity and plasma temperature are the same after 38 days, despite the high density and decreasing flux, is evidence for ongoing heating. We suggest the heating is due to a reverse shock in the nova ejecta, which forms a thin X-ray shell. The narrow RRCs and CX are attributed to direct mixing with cold gas, which overtakes the hot plasma either from the shock front or through the contact discontinuity.

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“…We can assume that we observe a small shell of material near the WD atmosphere that has recently been detached and is expanding, thus modeling the spectrum with a photoionization code for X-ray astronomy, assuming that the photoionizing source is a blackbody, whose temperature is a fit parameter. This has been done with varying results (Ness et al 2011;Orio et al 2021;Ness et al 2022;Milla & Paerels 2023). Sometimes, many shells have to be included to fit the spectra, introducing many variable parameters (Ness et al 2011), so the parameterization becomes more uncertain.…”

Section: The "Stormy" Luminous Supersoft X-ray Phasementioning

confidence: 99%

The RS Oph Outburst of 2021 Monitored in X-Rays with NICER

Orio,

Gendreau,

Giese

et al. 2023

ApJ

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The 2021 outburst of the symbiotic recurrent nova RS Oph was monitored with the Neutron Star Interior Composition Explorer Mission (NICER) in the 0.2–12 keV range from day one after the optical maximum, until day 88, producing an unprecedented, detailed view of the outburst development. The X-ray flux preceding the supersoft X-ray phase peaked almost 5 days after optical maximum and originated only in shocked ejecta for 21–25 days. The emission was thermal; in the first 5 days, only a non-collisional-ionization equilibrium model fits the spectrum, and a transition to equilibrium occurred between days 6 and 12. The ratio of peak X-ray flux measured in the NICER range to that measured with Fermi in the 60 MeV–500 GeV range was about 0.1, and the ratio to the peak flux measured with H.E.S.S. in the 250 GeV–2.5 TeV range was about 100. The central supersoft X-ray source (SSS), namely the shell hydrogen burning white dwarf (WD), became visible in the fourth week, initially with short flares. A huge increase in flux occurred on day 41, but the SSS flux remained variable. A quasi-periodic oscillation every ≃35 s was always observed during the SSS phase, with variations in amplitude and a period drift that appeared to decrease in the end. The SSS has characteristics of a WD of mass >1 M ⊙. Thermonuclear burning switched off shortly after day 75, earlier than in the 2006 outburst. We discuss implications for the nova physics.

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The High-resolution Soft X-Ray Spectrum of Nova Delphini 2013

Cited by 3 publications

References 19 publications

A Multiwavelength Light-curve Model of the Classical Nova V339 Del: A Mechanism for the Coexistence of Dust Dip and Supersoft X-Rays

A Multiwavelength Light-curve Model of the Classical Nova V339 Del: A Mechanism for the Coexistence of Dust Dip and Supersoft X-Rays

Mixing of Hot Shocked Plasma with Cold Gas in Nova YZ Ret 2020

The RS Oph Outburst of 2021 Monitored in X-Rays with NICER

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