20 years of Hubble Space Telescope optical modeling using Tiny Tim

Krist, John; Hook, R. N.; Stoehr, F.

doi:10.1117/12.892762

Cited by 360 publications

(191 citation statements)

References 19 publications

(16 reference statements)

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“…A crucial point in the deconvolution process is the partial PSF construction: the more accurate the partial PSF, the better the deconvolution (e.g., Letawe et al 2008). We derive the partial PSFs by deconvolving the models made with the Spitzer Tiny Tim Point Spread Function Program (Krist 2002) available on the Spitzer website for the different array locations. We compute the statistical weight of every pixel for every image to discard cosmic hits and other deviant pixels during the deconvolution process.…”

Section: Mips Observationsmentioning

confidence: 99%

A global analysis ofSpitzerand new HARPS data confirms the loneliness and metal-richness of GJ 436 b

Lanotte

Gillon

Demory

et al. 2014

A&A

130

135

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Context. GJ 436b is one of the few transiting warm Neptunes for which a detailed characterisation of the atmosphere is possible, whereas its non-negligible orbital eccentricity calls for further investigation. Independent analyses of several individual datasets obtained with Spitzer have led to contradicting results attributed to the different techniques used to treat the instrumental effects. Aims. We aim at investigating these previous controversial results and developing our knowledge of the system based on the full Spitzer photometry dataset combined with new Doppler measurements obtained with the HARPS spectrograph. We also want to search for additional planets. Methods. We optimise aperture photometry techniques and the photometric deconvolution algorithm DECPHOT to improve the data reduction of the Spitzer photometry spanning wavelengths from 3-24 µm. Adding the high-precision HARPS radial velocity data, we undertake a Bayesian global analysis of the system considering both instrumental and stellar effects on the flux variation.Results. We present a refined radius estimate of R P = 4.10 ± 0.16 R ⊕ , mass M P = 25.4 ± 2.1 M ⊕ , and eccentricity e = 0.162 ± 0.004 for GJ 436b. Our measured transit depths remain constant in time and wavelength, in disagreement with the results of previous studies. In addition, we find that the post-occultation flare-like structure at 3.6 µm that led to divergent results on the occultation depth measurement is spurious. We obtain occultation depths at 3.6, 5.8, and 8.0 µm that are shallower than in previous works, in particular at 3.6 µm. However, these depths still appear consistent with a metal-rich atmosphere depleted in methane and enhanced in CO/CO 2 , although perhaps less than previously thought. We could not detect a significant orbital modulation in the 8 µm phase curve. We find no evidence of a potential planetary companion, stellar activity, or a stellar spin-orbit misalignment. Conclusions. Recent theoretical models invoking high-metallicity atmospheres for warm Neptunes are a reasonable match to our results, but we encourage new modelling efforts based on our revised data. Future observations covering a wide wavelength range of GJ 436b and other Neptune-class exoplanets will further illuminate their atmosphere properties, whilst future accurate radial velocity measurements might explain the eccentricity.

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Section: Mips Observationsmentioning

confidence: 99%

A global analysis ofSpitzerand new HARPS data confirms the loneliness and metal-richness of GJ 436 b

Lanotte

Gillon

Demory

et al. 2014

A&A

130

135

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“…To eliminate the reflected sunlight, model spectral images are generated by mapping the solar UV spectrum from the day of the observation (33) onto a homogeneously bright disk of Europa. The disk images are convolved with a wavelength-dependent point spread function (PSF) (34) to account for the instrument scattering. By fitting the modeled spectral images to the observed brightness between 1430 Å and 1530 Å a geometric far-ultraviolet (FUV) albedo of 1.7% is measured for both the January (Fig.…”

Section: Data Processingmentioning

confidence: 99%

Orbital apocenter is not a sufficient condition for HST/STIS detection of Europa’s water vapor aurora

Roth

Retherford

Saur

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

113

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Significance Images of Europa’s UV aurora taken by the Hubble Space Telescope in December 2012 have revealed local hydrogen and oxygen emissions in intensity ratios that identify the source as electron impact excitation of water molecules. The existence of water vapor plumes as a source for the detected localized water vapor and the possible accessibility of subsurface liquid water reservoirs at these locations have important implications for the exploration of Europa’s potentially habitable environments. The observations reported here tested whether orbital position near the apocenter is an essential requirement for plume activity. Only an upper limit on the amount of water vapor was obtained. Orbital position is therefore not a sufficient condition for detecting plumes and they may be episodic events.

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“…Because the field of view in these observations is small and we study UV wavelengths, there were no stars in common to all filters that could be used to match the PSF. Instead, we created models of the PSFs using the techniques described in Krist et al (2011). Details of the PSF modeling and computing optimum convolution kernels will be presented in Melinder et al (in prep.).…”

Section: Hst Data Reductionmentioning

confidence: 99%

The Lyman alpha reference sample

Duval

Östlin

Hayes

et al. 2016

A&A

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Context. Recent numerical simulations suggest that the strength of the Lyman alpha (Lyα) line of star-forming disk galaxies strongly depends on the inclination at which they are observed: from edge-on to face-on, we expect to see a change from a strongly attenuated Lyα line to a strong Lyα emission line. Aims. We aim to understand how a strong Lyα emission line is able to escape from the low-redshift highly inclined (edge-on) disk galaxy Mrk 1486 (z ∼ 0.0338). To our knowledge, this work is the first observational study of Lyα transport inside an edge-on disk galaxy. Methods. Using a large set of HST imaging and spectroscopic data, we investigated the interstellar medium (ISM) structure and the dominant source of Lyα radiation inside Mrk 1486. Moreover, using a 3D Monte Carlo Lyα radiation transfer code, we studied the radiative transfer of Lyα and UV continuum photons inside a 3D geometry of neutral hydrogen (HI) and dust that models the ISM structure at the galaxy center. Our numerical simulations predicted the Lyα line profile that we then compared to the one observed in the HST/COS spectrum of Mrk 1486. Results. While a pronounced Lyα absorption line emerges from the disk of Mrk 1486, very extended Lyα structures are observed at large radii from the galaxy center: a large Lyα-halo and two very bright Lyα regions located slightly above and below the disk plane. The analysis of IFU Hα spectroscopic data of Mrk 1486 indicates the presence of two bipolar outflowing halos of HI gas at the same location as these two bright Lyα regions. Comparing different diagnostic diagrams (such as [OIII] 5007 /Hβ versus [OI] 6300 /Hα) to photo-and shock-ionization models, we find that the Lyα production of Mrk 1486 is dominated by photoionization inside the galaxy disk. From this perspective, our numerical simulations succeed in reproducing the strength and shape of the observed Lyα emission line of Mrk 1486 by assuming a scenario in which the Lyα photons are produced inside the galaxy disk, travel along the outflowing halos, and scatter on cool HI materials toward the observer. Conclusions. Extended bipolar galactic winds are frequently observed from star-forming disk galaxies. Given the advantage Lyα photons take of such outflowing HI materials to easily escape from Mrk 1486, this mechanism may explain the origin of strong Lyα emission lines frequently observed from highly inclined galaxies at high-redshift. This therefore challenges the robustness of the expected viewing-angle effect on the Lyα properties of star-forming disk galaxies.

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20 years of Hubble Space Telescope optical modeling using Tiny Tim

Cited by 360 publications

References 19 publications

A global analysis ofSpitzerand new HARPS data confirms the loneliness and metal-richness of GJ 436 b

A global analysis ofSpitzerand new HARPS data confirms the loneliness and metal-richness of GJ 436 b

Orbital apocenter is not a sufficient condition for HST/STIS detection of Europa’s water vapor aurora

The Lyman alpha reference sample

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