Pith. sign in

REVIEW 3 major objections 6 minor 44 references

This paper establishes the ejecta geometry of the fastest known galactic nova, V1674 Herculis, as a bipolar shell with polar blobs and an equatorial ring, and shows the system had returned to an accretion-dominated state by day 147.66.

Reviewed by Pith at T0; open to challenge. T0 means a machine referee read the full paper against a public rubric. the ladder, T0–T4 →

Challenge this review Re-run · record.json Download PDF Read on arXiv ↗

V1674 Her's ejecta is a bipolar shell with polar blobs and an equatorial ring, and by day 147 the system's spectrum is already accretion-dominated.

T0 review reviewed 2026-08-02 challenge →

load-bearing objection Useful follow-up data for the fastest known galactic nova, but the SHAPE morphology claim leans on an optical-depth assumption the paper never establishes. the 3 major comments →

arxiv 2602.19940 v2 pith:2OUOBKWN submitted 2026-02-23 astro-ph.HE astro-ph.SR

Optical observations of the fast nova V1674 Herculis

Neeraj Singh Rawat , L. S. Sonith , U. S. Kamath , Yash Bhargava , G. C. Anupama , Kulinder Pal Singh This is my paper
classification astro-ph.HE astro-ph.SR
keywords novaeV1674 Herculisbipolar ejectamorpho-kinematic modelingoptical spectroscopycataclysmic variablesLyman-beta fluorescenceaccretion disks
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

The paper tracks the optical spectrum and light curve of the fastest known galactic nova, V1674 Herculis, over 150 days after eruption. It argues that the Hα line profile is reproduced only by a 3D ejecta shape consisting of a bipolar shell with dense polar blobs and an equatorial ring, viewed at an inclination of about 65 degrees. It also finds that by day 147 the system is not yet in quiescence but is dominated by accretion, with narrow lines coming from an irradiated disk. These results matter because they constrain the geometry of an extreme, record-breaking eruption and show how quickly a nova can transition back toward its pre-eruption state.

Core claim

At two epochs, day 25.68 and day 65.86 after eruption, the observed Hα line profile of V1674 Herculis is well reproduced by a morpho-kinematic model consisting of a bipolar shell, polar blobs, and an equatorial ring, expanding under Hubble flow at an inclination of 65°. Simpler geometries fail to match the corrugated, multi-peaked profile. The model shows the polar cones broaden slightly between epochs. By day 147.66, the spectrum is accretion-dominated: He II and Balmer lines narrow to about 1500 km/s, and a rising blue continuum indicates emission from an irradiated disk rather than the original ejecta.

What carries the argument

The central tool is the SHAPE morpho-kinematic code, which builds a 3D geometric model of the ejecta and synthesizes a 1D line profile for comparison with the observed Hα profile. The model assumes optically thin emission, a r^-3 density falloff, and a Hubble-flow velocity field. The defining components—bipolar shell, polar blobs, equatorial ring—are assembled from geometric primitives with a 'squeeze' modifier to create the bipolar pinch. The inclination angle is the primary free parameter, settled at 65°.

Load-bearing premise

The 3D model assumes the Hα line is optically thin and that the line profile is set by the global ejecta geometry, but the paper itself notes Hα had large optical depth in the earliest June spectra and does not demonstrate that the line became optically thin by the two modeled epochs.

What would settle it

Measure the Hα to Hβ flux ratio (or the Paschen-to-Balmer decrement) at day 25.68 and day 65.86; if the ratio is significantly larger than the Case-B recombination value (about 2.8–3.0), the Hα emission is not optically thin and the uniqueness of the bipolar-shell-plus-ring geometry fails. Alternatively, obtain spatially resolved imaging of the ejecta at day 65 and compare the observed projected axis ratio and brightness distribution with the model's prediction.

Watch this falsifier. Get emailed when new claim-graph text bears on it.

If this is right

  • If the inferred geometry is right, even the fastest known galactic nova produces the same bipolar-plus-ring structure seen in slower novae, weakening the idea that faster eruptions are necessarily less shaped.
  • The ejecta morphology stays consistent from day 25 to day 66, meaning the global 3D structure is set early in the eruption and persists without major reorganisation.
  • The accretion-dominated spectrum on day 147 shows the white dwarf survived the extremely rapid eruption and is still hot enough to photoionise the accretion disk, so continued monitoring should track the return to true quiescence.
  • The presence of [Ne III] and [Ne V] lines confirms an ONe white dwarf in V1674 Her, linking the fastest known nova to a massive, oxygen-neon white dwarf progenitor.
  • The strong O I 8446 Å to 7774 Å ratio identifies Lyman-beta fluorescence as the dominant excitation channel for neutral oxygen, a diagnostic that can be applied to other fast novae.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • If the equatorial ring in the model is tied to the binary orbital plane, the 65° inclination combined with the 0.153-day orbital period could constrain the masses in the system and the geometry of the accretion flow.
  • The non-detection of the 501-second spin modulation in optical light down to ~0.04 magnitudes suggests the spin signal seen in X-rays is produced close to the white dwarf and is not imprinted strongly on the optical continuum, at least around day 40.
  • A direct test of the model would be imaging the ejecta with sub-arcsecond resolution; the model predicts a biconical nebula with a bright equatorial ring, while an alternative optically thick interpretation would predict a patchier appearance.
  • The paper's reliance on Hα alone, which is often optically thick, means the geometry could be checked by modelling a forbidden line like [O III] 5007 from the same epochs; if it gives a different shape, the inferred bipolar-ring structure would need revision.
Share X Bluesky LinkedIn Reddit HN

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit.

Referee Report

3 major / 6 minor

Summary. This paper presents optical photometry (GIT and AAVSO) and nine epochs of HCT/HFOSC spectroscopy of the fast nova V1674 Her covering days 0.84 to 147.66 after eruption. From AAVSO data the authors report an orbital period of ~0.153 d, consistent with earlier work, and place upper limits on any spin modulation in the GIT high-cadence data. The spectra show a rise in ionisation, with [Ne III] and [Ne V] appearing by day 19.87, supporting an ONe white dwarf. The paper argues that Lyman-beta fluorescence excites O I 8446 Å, and it uses SHAPE to model the Hα line profiles on days 25.68 and 65.86, concluding that the ejecta are a bipolar shell with polar blobs and an equatorial ring seen at inclination 65°. The day 147.66 spectrum is interpreted as accretion-dominated on the basis of narrow He II 4686 Å and a rising blue continuum.

Significance. If the morphology conclusion is correct, this is a useful addition to the small sample of fast novae with constrained ejecta geometry, and it complements the early-time CHARA resolved imaging of V1674 Her. The multi-epoch spectroscopic sequence itself is valuable and will be a reference dataset. The orbital-period measurement and the O I fluorescence analysis are sound and consistent with previous results. The spin-modulation injection simulations are a strength: they give quantitative detection limits rather than an unsupported non-detection. The central morpho-kinematic claim is, however, not established to the required standard because the SHAPE modelling does not demonstrate that Hα is optically thin at the modelled epochs, and the model is initialised using the same geometrical configuration and parameter values that it is then claimed to confirm.

major comments (3)
  1. [Section 6, Section 5.3, Figure 10] The SHAPE analysis is valid only if Hα is optically thin. The paper itself notes this in Section 6 and states that Lyman-beta fluorescence indicates large Hα optical depth in the June spectra, then selects day 25.68 as the first modelling epoch. But Section 5.3 and Figure 10 show that O I 8446 Å — the fluorescence indicator — is still present on day 25.68 and only becomes weak on day 37.88. The authors therefore have not shown that Hα is optically thin at the first modelled epoch. The multiple sub-peaks attributed to polar blobs and an equatorial ring could instead be radiative-transfer effects. I ask for a quantitative test (e.g. Hα/Hβ ratios, comparison of Hα and Hβ profiles, or an optical-depth estimate) at both modelled epochs, or a re-analysis using only day 65.86 where the fluorescence has disappeared.
  2. [Section 6, Eq. (1), text following Eq. (1)] The agreement with Habtie et al. (2024) is not an independent confirmation. The model starts from a spheroidal shell with an equatorial ring and polar caps (taken from Gill & O'Brien 1999 and Habtie et al.), the inclination search is concentrated in 55°–75° on the basis of the same prior results, the initial density is taken from Habtie et al., and the position angle of 35° is stated to be consistent with Habtie et al. Under these conditions, recovering a bipolar shell + polar blobs + equatorial ring is largely a restatement of the input. The statement that simpler geometries were tried is not supported by any quantitative comparison. I request a robustness test with a different initial geometry (e.g. a filled sphere or a uniform shell) and with the inclination allowed to vary over the full 0–90° range, reporting the rms and K for each case.
  3. [Section 6, Eq. (3), Figure 24, Table 3] The quality-of-fit statement is not adequately supported. For day 25.68 the reported rms is 0.2752 (Figure 24), which corresponds to an average deviation of ~28% between model and observed flux; calling this 'well reproduced' overstates the agreement. The K factor in Eq. (3) depends on an assumed 10% flux error (sigma=0.1) but no actual flux uncertainties are given anywhere, including Table 3, and the period, FWHM velocities, and SHAPE parameters (i=65°, PA=35°, densities, squeeze) are quoted without error bars. Without uncertainties on the input spectra or the model parameters, one cannot assess whether the two epochs require the same morphology or whether the claimed structure is unique. Please provide error estimates for the line fluxes and model parameters, and report the fit statistics alongside the assumptions.
minor comments (6)
  1. [Section 4.2] In the day 37.88 paragraph, 'a weak emission on day 25.86' appears to be a typo for day 25.68.
  2. [Section 5.4] The text says '[Ne III] and [Ne V] lines persist ... until day 65.66', which should presumably be day 65.86.
  3. [Section 3 and Table 3] The orbital periods are quoted as 0.15307 and 0.15321 d without uncertainties; the abstract rounds to 0.153 d. An uncertainty estimate is needed for a quantitative comparison with the literature value.
  4. [Section 4.1, Figure 9] The FWHM and FWZI velocities are given in the text without uncertainties. Since these numbers are used to set the SHAPE radius scale, error bars should be provided or the values should be presented as estimates only.
  5. [Section 7, point (v)] The day 147.66 spectrum is described as accretion-dominated on the basis of narrow He II 4686 Å and a rising blue continuum, yet strong [O III] nebular lines are still present and the nova has 'not yet returned to quiescence'. The wording is somewhat contradictory; a more cautious phrasing such as 'the optical spectrum at this epoch is dominated by accretion-related emission, with residual nebular lines' would be clearer.
  6. [References] The Aydi et al. (2025) reference is cited as 'Nature Astronomy, pp 1–10' and may need a volume/article number once available. Also, the acknowledgement line 'GCAnd KPS thank...' has a spacing typo.

Circularity Check

1 steps flagged

The inferred bipolar+ring+polar-blob morphology is the SHAPE model's initial ansatz, seeded with Habtie et al.'s density, inclination range, and position angle, so the 'agreement with Habtie et al.' is partly by construction.

specific steps
  1. ansatz smuggled in via citation [Section 6 ('ANALYSIS OF Hα LINE PROFILE USING SHAPE'), initial-geometry paragraph through final paragraph; also conclusion (vii).]
    "the initial geometry of the ejecta structure was created, starting with the assumption of a spheroidal shell featuring an equatorial ring and polar caps. ... the initial density value was taken from Habtie et al. (2024). ... the primary modelling effort was concentrated within 55°–75° ... We found a position angle of 35°, consistent with the value reported by Habtie et al. (2024) ... At both epochs, the observed Hα line profiles are well reproduced by a morphology consisting of a bipolar shell, with polar blobs and an equatorial ring, similar to the configuration reported by Habtie et al. (202"

    The morphology reported as inferred—bipolar shell with polar blobs and equatorial ring—is the same configuration used to initialize the SHAPE model (spheroidal shell + equatorial ring + polar caps). The inclination search was restricted to 55°–75° using the same Gill & O'Brien and Habtie et al. comparisons that are later quoted as agreement; initial density and position angle were taken from Habtie et al. (2024). Thus the statement that the profiles are 'well reproduced' by a morphology 'similar to Habtie et al. (2024)' is partly an output of the assumed initial ansatz and priors, not an independent confirmation. The circularity is partial: simpler geometries were tried and failed, and rms/K fits are reported.

full rationale

Most of the paper is self-contained and non-circular. The orbital period is measured from AAVSO data after detrending; the spin non-detection uses injection simulations to set amplitude upper limits; the O I fluorescence mechanism is tested against recombination and continuum-fluorescence expectations; the ONe classification follows directly from [Ne III] and [Ne V] detections; and the day 147.66 accretion-dominated interpretation is based on spectral morphology and FWHM changes. None of these reduce to their inputs by construction. The only load-bearing circular element is the Section 6 morpho-kinematic inference. The SHAPE model is initialized with a spheroidal shell, equatorial ring, and polar caps—the very components later reported as the inferred morphology—and the inclination range, initial density, and position angle are taken from the same Habtie et al. and Gill & O'Brien comparisons that are then invoked as agreement. Therefore the central morphology claim is partly seeded by its own assumptions. Some independent content remains: simpler geometries were explored and rejected, quantitative fit statistics are given, and the separate CHARA imaging of Aydi et al. (2025) supports non-spherical ejecta. The Hα optical-depth concern is a validity/uniqueness caveat rather than a circular step, so it does not itself raise the circularity score further.

Axiom & Free-Parameter Ledger

5 free parameters · 5 axioms · 0 invented entities

The paper's conclusions are mostly empirical, so the parameter burden is concentrated in the SHAPE morpho-kinematic modelling, where geometry, inclination, position angle, density profile, and velocity law are adjusted to reproduce a single line profile. No new physical entities are introduced. The reddening and several model inputs are adopted from prior work.

free parameters (5)
  • Inclination angle (SHAPE model) = 65°
    Adjusted in SHAPE to match the Hα profile; the search was concentrated in 55°–75° based on Habtie et al. (2024) and Gill & O'Brien (1999).
  • Position angle (SHAPE model) = 35°
    Sampled over 0°–180°; the final value was chosen to reproduce the profile and is consistent with Habtie et al. (2024).
  • Hubble-flow velocity normalization = 3200/sin i km/s (Eq. 1)
    The velocity law V_exp = 3200/sin i × r/r0 is assumed; the 3200 km/s normalization is inferred from the Hα FWHM and the r/r0 scaling is assumed.
  • Density normalization and r^-3 profile = initial density from Habtie et al. (2024)
    The density profile is assumed to vary as r^-3; the absolute density scale is borrowed from prior modeling, not independently measured.
  • Squeeze parameter / component radii and densities = not quantified in text
    SHAPE modifiers were adjusted qualitatively to reproduce the observed profile morphology; final component parameters are not tabulated.
axioms (5)
  • domain assumption Hα emission at days 25.68 and 65.86 is optically thin enough for SHAPE's radiative-transfer assumptions.
    Section 6 acknowledges SHAPE was developed for optically thin environments and that Hα optical depth was large in June; the choice of modelling epochs assumes the line became optically thin later, but this is not demonstrated.
  • domain assumption The ejecta undergoes Hubble-flow-type expansion with V ∝ r.
    Adopted from Ribeiro (2011) and standard nova shell modelling; used in Eq. (1).
  • domain assumption The ejecta density varies as r^-3.
    Assumed for all SHAPE primitives; the initial density value is taken from Habtie et al. (2024).
  • standard math The O I 8446/7774 ratio thresholds (recombination gives ~0.6, Lyman-beta fluorescence gives a high ratio) are valid.
    Diagnostic from Strittmatter et al. (1977), used in Section 5.3 to identify the oxygen excitation mechanism.
  • domain assumption The adopted reddening E(B−V)=0.55 from Munari et al. (2021) is correct.
    All dereddened fluxes and line ratios depend on this value; the paper does not perform an independent reddening measurement.

reviewed 2026-08-02 · how reviews work

0 comments
Cite this review

Pith. "Pith review of Optical observations of the fast nova V1674 Herculis." pith.science (2026). https://pith.science/paper/2OUOBKWN

@misc{pith2026260219940,
  author       = {Pith},
  title        = {Pith review of: Optical observations of the fast nova V1674 Herculis},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/2OUOBKWN}},
  note         = {Machine review of arXiv:2602.19940}
}
Share X Bluesky LinkedIn Reddit HN
abstract

We present the evolution of optical spectra and lightcurves of the fast nova V1674 Herculis during 150 days past its eruption. Using the post-eruption AAVSO light curve, we have calculated the orbital period of V1674 Her to be 0.153 days. There is no unambiguous white dwarf spin period in our data. The optical spectra show that the ionisation increases with time. A morpho-kinematic analysis of the H$\alpha$ line profile indicates a bipolar morphology with polar blobs and an equatorial ring. Lyman beta fluorescence is found to be the dominant mechanism for the excitation of neutral oxygen. On day 19.87, [Ne III] & [Ne V] lines are present, indicating the presence of the ONe white dwarf. On day 147.66, the nebular lines are still present, implying that the nova had not gone into quiescence yet; this spectrum is accretion-dominated.

Figures

Figures reproduced from arXiv: 2602.19940 by G. C. Anupama, Kulinder Pal Singh, L. S. Sonith, Neeraj Singh Rawat, U. S. Kamath, Yash Bhargava.

Figure 1
Figure 1. Figure 1: Light curve of nova V1674 Her in the GIT g′ , r′ , i′ and z′ bands. Offset has been applied for individual bands except i′ band for better representation. Insets show the high cadence observations [PITH_FULL_IMAGE:figures/full_fig_p003_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: AAVSO V-band light curve of V1674 Her with the epochs of our spectroscopic observations marked by arrows. 10 2 10 1 10 0 10 1 Period (days) 0.0 0.1 0.2 0.3 0.4 0.5 Lomb-Scargle Power AAVSO V AAVSO CV [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: LS periodogram of V1674 Her for searching the orbital period in AAVSO V and CV bands. Both V and CV bands show a clear peak at ∼ 0.153 days, as shown by the dashed line. MNRAS 000, 1–16 (2026) [PITH_FULL_IMAGE:figures/full_fig_p003_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Phase folded light curve of V1674 Her in AAVSO V, CV and GIT r′ bands. The lightcurves are folded at the period seen in [PITH_FULL_IMAGE:figures/full_fig_p004_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: Spectral evolution of V1674 Her across eight epochs. Each epoch is labelled on the right side of the plot. The spectra have been given an offset for clarity. On the y-axis, the logarithm of flux is displayed, while the x-axis represents the wavelength. The logarithmic scale has been used to emphasise the visibility of weaker features. dominated spectrum. The detailed evolution of the optical spectra of V16… view at source ↗
Figure 6
Figure 6. Figure 6: Spectrum of V1674 Her on day +147.66. The nebular lines are still visible and are very strong. He II 4686 Å line is present and is stronger in strength compared to the Balmer lines. The presence of He II 4686 Å line and the rising continuum in the blue indicate an accretion-dominated spectrum. The early spectra of V1674 Her share similarities with the spectra of V2491 Cyg (Nova Cyg 2008 N.2) given by Munar… view at source ↗
Figure 9
Figure 9. Figure 9: Line profiles of H𝛼 and H𝛽 for nine epochs. For each epoch, the H𝛼 and H𝛽 flux values have been normalised to their respective local continuum. A common y-axis scale is adopted for the early epochs, while a reduced scale is used for the later epochs, where the line fluxes are significantly weaker. The lines display corrugated profiles with generally similar shapes. On day 0.84, asymmetry is observed, chara… view at source ↗
Figure 10
Figure 10. Figure 10: Evolution of the O I 8446 Å line. For each epoch, the flux has been normalised to the local continuum. The line reaches a peak in strength by day 5.73 and subsequently declines in later epochs. MNRAS 000, 1–16 (2026) [PITH_FULL_IMAGE:figures/full_fig_p007_10.png] view at source ↗
Figure 11
Figure 11. Figure 11: Evolution of the [Ne III] 3869 Å (left) & [Ne III] 3968 Å (right) emission lines. For each epoch, the [Ne III] 3869 Å & [Ne III] 3968 Å flux values have been normalised to their respective local continuum. In the initial spectra (day 0.84, 2.89 & 5.73) obtained shortly after the nova eruption, prominent hydrogen lines H𝜁 & H𝜖 are observed. However, as the eruption progressed and transitioned into the SSS … view at source ↗
Figure 12
Figure 12. Figure 12: Evolution of [Fe XI] 7892 Å. Dotted line represents the rest wavelength of [Fe XI] 7892 Å. In the early spectra (day 0.84, 2.89, & 5.73), the O I 7774 Å feature is visible. A weak emission line of [Fe XI] 7892 Å is observed on day 23.71, which becomes more prominent on day 37.88. However, [Fe XI] is absent on day 65.86. observed fluxes relative to H𝛽 for nebular lines has increased, while the value for H𝛼… view at source ↗
Figure 15
Figure 15. Figure 15: Evolution of the He I 7065 Å line. For each epoch, the flux has been normalised to the local continuum. Initially, on day 0.84, the profile appears flat without discernible substructures. However, distinct substructures emerge in the line profile as the nova evolves. For e.g. on day 5.73, 3 substructures can be seen. By day 65.86, the He I 7065 Å line has weakened significantly (see [PITH_FULL_IMAGE:figu… view at source ↗
Figure 16
Figure 16. Figure 16: Evolution of the He I 5876 Å line. The fluxes are scaled by a constant factor, as indicated in the legend. Dotted line represents the rest wavelength of He I 5876 Å. By day 65.86, the He I 5876 Å line has weakened significantly. Interstellar Na I (D) absorption lines are consistently observed across all epochs. 5.2 Helium Lines In the optical spectra of V1674 Her, both He I and He II lines appear and disa… view at source ↗
Figure 17
Figure 17. Figure 17: Velocity profiles of O I 8446 Å, He I 7065 Å, H𝛼, and H𝛽 on day 5.73. The line fluxes are normalised to their respective local continuum values and then scaled using different constant values, as indicated in the legend. 5.3 Oxygen Lines O I 8446 Å, O I 7774 Å, O I 8227 Å in combination with N I 8212 Å and O I 7477 Å in combination with NI 7452 Å are present in the optical spectrum on day 0.84. The streng… view at source ↗
Figure 20
Figure 20. Figure 20: Velocity profiles of [Ne III] 3869 Å, 3968 Å on day 25.68. The line fluxes are normalised to their respective local continuum values. [Ne III] 3968 Å line flux has been scaled by a constant number, as indicated in the legend. 𝜇m/1.1287 𝜇m ratio would exceed unity. However, in Woodward et al. (2021a), on day 5.64, in the NIR spectra of V1674 Her, it is ob￾served that the strength of the O I 1.3164 𝜇m line … view at source ↗
Figure 19
Figure 19. Figure 19: Evolution of the [O III] 4959 Å & 5007 Å emission line profile across nine epochs. Initially, on day 0.84, N II 5001 Å is present with possible contributions from He I 5016 Å & 5048 Å as well as Fe II (42) multiplet at 5018 Å. The [O III] 4959 Å & 5007 Å emission line emerges on day 19.87 and persists until day 147.66. 6000 4000 2000 0 2000 4000 6000 Velocity (km sec¡1) 1.0 1.5 2.0 2.5 3.0 3.5 4.0 N o r m… view at source ↗
Figure 21
Figure 21. Figure 21: Evolution of the [Ne V] 3426 Å line. The left panel shows the flux-calibrated spectra, while the right panel shows the same profiles, for each epoch, normalised to the local continuum. The [Ne V] 3426 Å line is first detected on day 19.87, coinciding with the appearance of the [Ne III] 3869 Å and 3968 Å lines, and persists until day 65.86. On day 147.66, it is difficult to confirm the presence of [Ne V] 3… view at source ↗
Figure 22
Figure 22. Figure 22: Evolution of [Fe XIV] 5303 Å. Dotted line represents the rest wavelength of [Fe XIV] 5303 Å. The emission feature became evident on day 19.87 and remained present until day 65.86. However, [Fe XIV] is absent on day 147.66. evolution of [Fe VII] 6087 Å and [Fe X] 6375 Å lines. The ‘Early spectra’ (see Section 4.1) potentially include the [O I] 6364 Å line, but as the ionisation conditions increase, [Fe X] … view at source ↗
Figure 23
Figure 23. Figure 23: Velocity profiles of coronal and high ionisation lines of iron on day 37.88. The line fluxes are normalised to their respective local continuum values and then scaled by a constant number, as indicated in the legend. (see [PITH_FULL_IMAGE:figures/full_fig_p013_23.png] view at source ↗
Figure 24
Figure 24. Figure 24: Observed (green solid line) and modelled (purple dashed line) H𝛼 line profiles of V1674 Her for day 25.68 (left) and day 65.86 (right). The velocity profiles are normalised to their respective peak flux values. 5.0 2.5 0.0 2.5 5.0 cm 1e15 5.0 2.5 0.0 2.5 5.0 cm 1e15 Day 25.68 5.0 2.5 0.0 2.5 5.0 cm 1e15 5.0 2.5 0.0 2.5 5.0 cm 1e15 Day 65.86 [PITH_FULL_IMAGE:figures/full_fig_p014_24.png] view at source ↗
Figure 25
Figure 25. Figure 25: Morphology of the ejecta of V1674 Her using H𝛼 line profile for day 25.68 (left) and day 65.86 (right) in the 2d plane with x-axis being the line-of-sight direction and the y-axis being the axis perpendicular to that of the plane of sky and line-of-sight. where 𝐹model and 𝐹obs are the integrated model and observed fluxes, respectively, and 𝜎 is the error in the observed line. A value of |𝐾| < 1 indicates … view at source ↗

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

44 extracted references · 5 canonical work pages

  1. [1]

    C., Kamath U

    Anupama G. C., Kamath U. S., 2012, Bulletin of the Astronomical Society of India, https://ui.adsabs.harvard.edu/abs/2012BASI...40..161A 40, 161

    2012

  2. [2]

    Astropy Collaboration et al., 2018, @doi [ ] 10.3847/1538-3881/aabc4f , https://ui.adsabs.harvard.edu/abs/2018AJ....156..123A 156, 123

    doi:10.3847/1538-3881/aabc4f 2018

  3. [3]

    Aydi E., et al., 2025, @doi [Nature Astronomy] 10.1038/s41550-025-02725-1 , pp 1--10

    doi:10.1038/s41550-025-02725-1 2025

  4. [4]

    Bhargava Y., et al., 2024, @doi [ ] 10.1093/mnras/stad3870 , https://ui.adsabs.harvard.edu/abs/2024MNRAS.528...28B 528, 28

    doi:10.1093/mnras/stad3870 2024

  5. [5]

    J., et al., 2021, @doi [ ] 10.3847/2041-8213/ac34fd , https://ui.adsabs.harvard.edu/abs/2021ApJ...922L..42D 922, L42

    Drake J. J., et al., 2021, @doi [ ] 10.3847/2041-8213/ac34fd , https://ui.adsabs.harvard.edu/abs/2021ApJ...922L..42D 922, L42

    doi:10.3847/2041-8213/ac34fd 2021

  6. [6]

    D., O'Brien T

    Gill C. D., O'Brien T. J., 1999, @doi [ ] 10.1046/j.1365-8711.1999.02681.x , https://ui.adsabs.harvard.edu/abs/1999MNRAS.307..677G 307, 677

    arXiv 1999

  7. [7]

    R., Das R., Pandey R., Ashok N

    Habtie G. R., Das R., Pandey R., Ashok N. M., Dubovsky P. A., 2024, @doi [ ] 10.1093/mnras/stad3295 , https://ui.adsabs.harvard.edu/abs/2024MNRAS.527.1405H 527, 1405

    doi:10.1093/mnras/stad3295 2024

  8. [8]

    B., 1972, @doi [ ] 10.1093/mnras/158.2.177 , https://ui.adsabs.harvard.edu/abs/1972MNRAS.158..177H 158, 177

    Hutchings J. B., 1972, @doi [ ] 10.1093/mnras/158.2.177 , https://ui.adsabs.harvard.edu/abs/1972MNRAS.158..177H 158, 177

    work page doi:10.1093/mnras/158.2.177 1972

  9. [9]

    https://www.aavso.org

    Kafka S., 2021, Observations from the AAVSO International Database. https://www.aavso.org

    2021

  10. [10]

    Kawash A., et al., 2021, @doi [ ] 10.3847/1538-4357/abe53d , https://ui.adsabs.harvard.edu/abs/2021ApJ...910..120K 910, 120

    doi:10.3847/1538-4357/abe53d 2021

  11. [11]

    Kumar H., et al., 2022a, @doi [ ] 10.3847/1538-3881/ac7bea , https://ui.adsabs.harvard.edu/abs/2022AJ....164...90K 164, 90

    doi:10.3847/1538-3881/ac7bea

  12. [12]

    Kumar H., et al., 2022b, @doi [ ] 10.1093/mnras/stac2516 , https://ui.adsabs.harvard.edu/abs/2022MNRAS.516.4517K 516, 4517

    work page doi:10.1093/mnras/stac2516

  13. [13]

    C.-C., Fan J.-L., Hu C.-P., Takata J., Li K.-L., 2022, @doi [ ] 10.1093/mnrasl/slac117 , https://ui.adsabs.harvard.edu/abs/2022MNRAS.517L..97L 517, L97

    Lin L. C.-C., Fan J.-L., Hu C.-P., Takata J., Li K.-L., 2022, @doi [ ] 10.1093/mnrasl/slac117 , https://ui.adsabs.harvard.edu/abs/2022MNRAS.517L..97L 517, L97

    doi:10.1093/mnrasl/slac117 2022

  14. [14]

    R., 1976, @doi [ ] 10.1007/BF00648343 , https://ui.adsabs.harvard.edu/abs/1976Ap&SS..39..447L 39, 447

    Lomb N. R., 1976, @doi [ ] 10.1007/BF00648343 , https://ui.adsabs.harvard.edu/abs/1976Ap&SS..39..447L 39, 447

    doi:10.1007/bf00648343 1976

  15. [15]

    Luna G. J. M., Lima I. J., Orio M., 2024, @doi [Boletin de la Asociacion Argentina de Astronomia La Plata Argentina] 10.48550/arXiv.2310.02220 , https://ui.adsabs.harvard.edu/abs/2024BAAA...65...60L 65, 60

    Pith/arXiv arXiv doi:10.48550/arxiv.2310.02220 2024

  16. [16]

    J., Beardmore A., Mukai K., Page K., Pichardo Marcano M., Rivera Sandoval L., 2021, The Astronomer's Telegram, https://ui.adsabs.harvard.edu/abs/2021ATel14776....1M 14776, 1

    Maccarone T. J., Beardmore A., Mukai K., Page K., Pichardo Marcano M., Rivera Sandoval L., 2021, The Astronomer's Telegram, https://ui.adsabs.harvard.edu/abs/2021ATel14776....1M 14776, 1

    2021

  17. [17]

    Morisset C., Georgiev L., 2009, @doi [ ] 10.1051/0004-6361/200912413 , https://ui.adsabs.harvard.edu/abs/2009A&A...507.1517M 507, 1517

    doi:10.1051/0004-6361/200912413 2009

  18. [18]

    v., Prince T., Kong A

    Mroz P., Burdge K., Roestel J. v., Prince T., Kong A. K. H., Li K. L., 2021, The Astronomer's Telegram, https://ui.adsabs.harvard.edu/abs/2021ATel14720....1M 14720, 1

    2021

  19. [19]

    Munari U., Siviero A., Dallaporta S., Cherini G., Valisa P., Tomasella L., 2011, @doi [ ] 10.1016/j.newast.2010.08.010 , https://ui.adsabs.harvard.edu/abs/2011NewA...16..209M 16, 209

    work page doi:10.1016/j.newast.2010.08.010 2011

  20. [20]

    Munari U., Valisa P., Dallaporta S., 2021, The Astronomer's Telegram, https://ui.adsabs.harvard.edu/abs/2021ATel14704....1M 14704, 1

    2021

  21. [21]

    Nakano S., et al., 2008, , https://ui.adsabs.harvard.edu/abs/2008IAUC.8934....1N 8934, 1

    2008

  22. [22]

    L., Orio M., Sokolovsky K

    Page K. L., Orio M., Sokolovsky K. V., Kuin N. P. M., 2021, The Astronomer's Telegram, https://ui.adsabs.harvard.edu/abs/2021ATel14747....1P 14747, 1

    2021

  23. [23]

    Patterson J., et al., 2022, @doi [ ] 10.3847/2041-8213/ac9ebe , https://ui.adsabs.harvard.edu/abs/2022ApJ...940L..56P 940, L56

    doi:10.3847/2041-8213/ac9ebe 2022

  24. [24]

    Pei S., Luna G. J. M., Orio M., Behar E., Giese M., Mikolajewska J., Ness J.-U., 2021, The Astronomer's Telegram, https://ui.adsabs.harvard.edu/abs/2021ATel14798....1P 14798, 1

    2021

  25. [25]

    M., Shafter A

    Quimby R. M., Shafter A. W., Corbett H., 2021, @doi [Research Notes of the American Astronomical Society] 10.3847/2515-5172/ac14c0 , https://ui.adsabs.harvard.edu/abs/2021RNAAS...5..160Q 5, 160

    doi:10.3847/2515-5172/ac14c0 2021

  26. [26]

    Ribeiro V. A. R. M., 2011, PhD thesis, Liverpool John Moores University, UK

    2011

  27. [27]

    Ribeiro V. A. R. M., Darnley M. J., Bode M. F., Munari U., Harman D. J., Steele I. A., Meaburn J., 2011, @doi [ ] 10.1111/j.1365-2966.2010.18006.x , https://ui.adsabs.harvard.edu/abs/2011MNRAS.412.1701R 412, 1701

    arXiv 2011

  28. [28]

    D., 1982, @doi [ ] 10.1086/160554 , https://ui.adsabs.harvard.edu/abs/1982ApJ...263..835S 263, 835

    Scargle J. D., 1982, @doi [ ] 10.1086/160554 , https://ui.adsabs.harvard.edu/abs/1982ApJ...263..835S 263, 835

    doi:10.1086/160554 1982

  29. [29]

    Shugarov S., Afonina M., 2021, The Astronomer's Telegram, https://ui.adsabs.harvard.edu/abs/2021ATel14835....1S 14835, 1

    2021

  30. [30]

    J., O'Brien T

    Slavin A. J., O'Brien T. J., Dunlop J. S., 1995, @doi [ ] 10.1093/mnras/276.2.353 , https://ui.adsabs.harvard.edu/abs/1995MNRAS.276..353S 276, 353

    doi:10.1093/mnras/276.2.353 1995

  31. [31]

    X., Hix W

    Starrfield S., Iliadis C., Timmes F. X., Hix W. R., Arnett W. D., Meakin C., Sparks W. M., 2012, @doi [Bulletin of the Astronomical Society of India] 10.48550/arXiv.1210.6086 , https://ui.adsabs.harvard.edu/abs/2012BASI...40..419S 40, 419

    Pith/arXiv arXiv doi:10.48550/arxiv.1210.6086 2012

  32. [32]

    R., Woodward C

    Starrfield S., Bose M., Iliadis C., Hix W. R., Woodward C. E., Wagner R. M., 2020, @doi [ ] 10.3847/1538-4357/ab8d23 , https://ui.adsabs.harvard.edu/abs/2020ApJ...895...70S 895, 70

    doi:10.3847/1538-4357/ab8d23 2020

  33. [33]

    Steffen W., Koning N., Wenger S., Morisset C., Magnor M., 2011, @doi [IEEE Transactions on Visualization and Computer Graphics] 10.1109/TVCG.2010.62 , https://ui.adsabs.harvard.edu/abs/2011ITVCG..17..454S 17, 454

    doi:10.1109/tvcg.2010.62 2011

  34. [34]

    A., et al., 1977, @doi [ ] 10.1086/155438 , https://ui.adsabs.harvard.edu/abs/1977ApJ...216...23S 216, 23

    Strittmatter P. A., et al., 1977, @doi [ ] 10.1086/155438 , https://ui.adsabs.harvard.edu/abs/1977ApJ...216...23S 216, 23

    work page doi:10.1086/155438 1977

  35. [35]

    T., 2018, @doi [ ] 10.3847/1538-4365/aab766 , https://ui.adsabs.harvard.edu/abs/2018ApJS..236...16V 236, 16

    VanderPlas J. T., 2018, @doi [ ] 10.3847/1538-4365/aab766 , https://ui.adsabs.harvard.edu/abs/2018ApJS..236...16V 236, 16

    doi:10.3847/1538-4365/aab766 2018

  36. [36]

    M., Woodward C

    Wagner R. M., Woodward C. E., Starrfield S., Banerjee D. P. K., Evans A., 2021, The Astronomer's Telegram, https://ui.adsabs.harvard.edu/abs/2021ATel14746....1W 14746, 1

    2021

  37. [37]

    Warner B., 1995, Cataclysmic variable stars . Vol. 28

    1995

  38. [38]

    E., 1992, @doi [ ] 10.1086/116268 , https://ui.adsabs.harvard.edu/abs/1992AJ....104..725W 104, 725

    Williams R. E., 1992, @doi [ ] 10.1086/116268 , https://ui.adsabs.harvard.edu/abs/1992AJ....104..725W 104, 725

    doi:10.1086/116268 1992

  39. [39]

    Williams R., 2012, @doi [ ] 10.1088/0004-6256/144/4/98 , https://ui.adsabs.harvard.edu/abs/2012AJ....144...98W 144, 98

    work page doi:10.1088/0004-6256/144/4/98 2012

  40. [40]

    E., Banerjee D

    Woodward C. E., Banerjee D. P. K., Geballe T. R., Page K. L., Starrfield S., Wagner R. M., 2021a, @doi [ ] 10.3847/2041-8213/ac3518 , https://ui.adsabs.harvard.edu/abs/2021ApJ...922L..10W 922, L10

    doi:10.3847/2041-8213/ac3518 2041

  41. [41]

    E., et al., 2021b, The Astronomer's Telegram, https://ui.adsabs.harvard.edu/abs/2021ATel14723....1W 14723, 1

    Woodward C. E., et al., 2021b, The Astronomer's Telegram, https://ui.adsabs.harvard.edu/abs/2021ATel14723....1W 14723, 1

  42. [42]

    E., Banerjee D

    Woodward C. E., Banerjee D. P. K., Wagner R. M., Starrfield S., Evans A., 2021c, The Astronomer's Telegram, https://ui.adsabs.harvard.edu/abs/2021ATel14728....1W 14728, 1

  43. [43]

    E., Banerjee D

    Woodward C. E., Banerjee D. P. K., Evans A., Wagner R. M., Starrfield S., 2021d, The Astronomer's Telegram, https://ui.adsabs.harvard.edu/abs/2021ATel14741....1W 14741, 1

  44. [44]

    M., Kovetz A., 2005, @doi [ ] 10.1086/428435 , https://ui.adsabs.harvard.edu/abs/2005ApJ...623..398Y 623, 398

    Yaron O., Prialnik D., Shara M. M., Kovetz A., 2005, @doi [ ] 10.1086/428435 , https://ui.adsabs.harvard.edu/abs/2005ApJ...623..398Y 623, 398

    doi:10.1086/428435 2005

This paper was first reviewed by deepseek-v4-flash on August 2, 2026.