The recent expansion of Pluto's atmosphere

Elliot, J. L.; Ateş, Ali; Babcock, B. A.; Bosh, A. S.; Buie, M. W.; Clancy, K. B.; Dunham, E. W.; Eikenberry, S. S.; Hall, D. T.; Kern, S.; Leggett, S. K.; Levine, S. E.; Moon, D. S.; Olkin, C. B.; Osip, D. J.; Pasachoff, Jay M.; Penprase, Bryan E.; Qu, S.; Rayner, John; Roberts, Lewis C.; Salyk, Colette; Souza, S. P.; Stone, R. C.; Taylor, B.; Tholen, David J.; Thomas-Osip, J. E.; Ticehurst, D. R.; Wasserman, L. H.

doi:10.1038/nature01762

Cited by 113 publications

(89 citation statements)

References 25 publications

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“…To quantify this statement, we combined our spectroscopic data with a new assessment of stellar occultation lightcurves. Besides the isothermal part and the "kink" feature mentioned previously, recent high-quality, occultation curves (Sicardy et al 2003;Elliot et al 2003Elliot et al , 2007E. Young et al 2008;) exhibit several remarkable characteristics: (i) a low residual flux during occultation, typically less than 3% of the unattenuated stellar flux; (ii) the conspicuous absence of caustic spikes in the bottom part of the lightcurves; (iii) the existence of a central flash caused by Pluto's limb curvature, in occultations in which the Earth passed near the geometric center of the shadow.…”

Section: Combination With Inferences From Stellar Occultationsmentioning

confidence: 99%

“…Pluto's upper atmosphere is isothermal (T ∼ 100 K at altitudes above 1215 km from Pluto's center) and has undergone a pressure expansion by a factor of 2 from 1988 to 2002, probably related to seasonal cycles, followed by a stabilization over 2002(Sicardy et al 2003Elliot et al 2003Elliot et al , 2007; E. ). Below the 1215 km level, occultation lightcurves are characterized by a sharp drop ("kink") in flux, interpreted as due to either a ∼10 km-thick thermally inverted layer (stratosphere) or absorption by a low-altitude haze with significant opacity (>0.15 in vertical viewing).…”

Section: Introductionmentioning

confidence: 99%

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Pluto's lower atmosphere structure and methane abundance from high-resolution spectroscopy and stellar occultations

Lellouch¹,

Sicardy

Bérgh³

et al. 2009

A&A

119

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Context. Pluto possesses a thin atmosphere, primarily composed of nitrogen, in which the detection of methane has been reported. Aims. The goal is to constrain essential but so far unknown parameters of Pluto's atmosphere, such as the surface pressure, lower atmosphere thermal stucture, and methane mixing ratio. Methods. We use high-resolution spectroscopic observations of gaseous methane and a novel analysis of occultation lightcurves. Results. We show that (i) Pluto's surface pressure is currently in the 6.5-24 μbar range, (ii) the methane mixing ratio is 0.5 ± 0.1%, adequate to explain Pluto's inverted thermal structure and ∼100 K upper atmosphere temperature, and (iii) a troposphere is not required by our data, but if present, it has a depth of at most 17 km, i.e. less than one pressure scale height; in this case methane is supersaturated in most of it. The atmospheric and bulk surface abundances of methane are strikingly similar, a possible consequence of a CH 4 -rich top surface layer.

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Section: Combination With Inferences From Stellar Occultationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Pluto's lower atmosphere structure and methane abundance from high-resolution spectroscopy and stellar occultations

Lellouch¹,

Sicardy

Bérgh³

et al. 2009

A&A

119

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“…Its upper atmosphere is isothermal with T ≈ 100 K above about 1215 km from the center. Pressure roughly doubled between 1988-2002 after Pluto s 1989 perihelion passage and then stabilized over 2002−2007(Sicardy et al 2003Elliot et al 2003Elliot et al , 2007Young et al 2008). Pluto s atmosphere is thought to be mainly N 2 , with a measured CH 4 abundance of 0.5% ± 0.1% and some undetermined amount of CO (Lellouch et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Precise predictions of stellar occultations by Pluto, Charon, Nix, and Hydra for 2008–2015

Assafin¹,

Camargo

Martins

et al. 2010

A&A

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Context. We investigate transneptunian objects, including Pluto and its satellites, by stellar occultations. Aims. Our aim is to derive precise, astrometric predictions for stellar occultations by Pluto and its satellites Charon, Hydra and Nix for 2008−2015. We construct an astrometric star catalog in the UCAC2 system covering Pluto s sky path. Conclusions. Recurrent issues in stellar occultation predictions were addressed and properly overcome: body ephemeris offsets, catalog zero-point position errors and field-of-view size, long-term predictions and stellar proper motions, faint-visual versus brightinfrared stars and star/body astrometric follow-up. In particular, we highlight the usefulness of the obtained astrometric catalog as a reference frame for star/body astrometric follow-up before and after future events involving the Pluto system. Besides, it also furnishes useful photometric information for field stars in the flux calibration of observed light curves. Updates on the ephemeris offsets and candidate star positions (geometric conditions of predictions and finding charts) are made available by the group at www.lesia. obspm.fr/perso/bruno-sicardy/. Also based on observations made at

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“…The atmosphere could only be more extensively observed in the next occultation in 1988 (Millis et al 1993). In 2002, a new stellar occultation by Pluto was recorded, but with higher time resolution (Sicardy et al 2003;Elliot et al 2003), revealing that there had been a dramatic expansion in the atmosphere pressure. Another high signal-to-noise ratio (S/N) light curve was obtained in the June 2006 stellar occultation (Young et al 2008), which uncovered evidence of the stabilization of the atmosphere pressure in Pluto for the period [2002][2003][2004][2005][2006][2007][2008].…”

Section: Introductionmentioning

confidence: 99%

Candidate stellar occultations by large trans-Neptunian objects up to 2015

Assafin¹,

Camargo²,

Martins³

et al. 2012

A&A

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Context. We study large trans-Neptunian objects (TNOs) using stellar occultations. Aims. We derive precise astrometric predictions for stellar occultations by Eris, Haumea, Ixion, Makemake, Orcus, Quaoar, Sedna, Varuna, 2002 TX 300 , and 2003 AZ 84 for 2011-2015. We construct local astrometric catalogs of stars complete to magnitudes as faint as R = 18−19 in the UCAC2 (Second US Naval Observatory CCD Astrograph Catalog) frame covering the sky path of these objects. We performed the astrometry of 316 GB images using the Platform for Reduction of Astronomical Images Automatically (PRAIA). With the help of field distortion patterns derived for the WFI mosaic of CCDs, we reduced the overlapping mosaics of CCDs. Results. We derive positions in the UCAC2 frame with 40 mas precision for stars up to the catalog magnitude completeness limit (about R = 19). New stellar proper motions are also determined with 2MASS (Two Micron All Sky Survey) and the USNO B1.0 (United States Naval Observatory B 1.0) catalog positions as a first epoch. Astrometric catalogs with proper motions were produced for each TNO, containing more than 5.35 million stars covering the sky paths with 30 width in declination. The magnitude completeness is about R = 19 with a limit of about R = 21. We predicted 2717 stellar occultation candidates for all targets. Ephemeris offsets with about from 50 mas to 100 mas precision were applied to each TNO orbit to improve the predictions. They were obtained during 2007-2010 from a parallel observational campaign carried out with telescopes from 0.6 m to 2.2 m in size. Conclusions. This extends our previous work for the Pluto system to large TNOs, using the same observational and astrometric procedures. The obtained astrometric catalogs are useful for follow-up programs at small to large telescopes used to improve the candidate star positions and TNO ephemeris. They also furnish valuable photometric information for the field stars. For each TNO, updates on the ephemeris offsets and candidate star positions (geometric conditions of predictions and finding charts) are made available by the group at http://www.lesia.obspm.fr/perso/bruno-sicardy/.

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The recent expansion of Pluto's atmosphere

Cited by 113 publications

References 25 publications

Pluto's lower atmosphere structure and methane abundance from high-resolution spectroscopy and stellar occultations

Pluto's lower atmosphere structure and methane abundance from high-resolution spectroscopy and stellar occultations

Precise predictions of stellar occultations by Pluto, Charon, Nix, and Hydra for 2008–2015

Candidate stellar occultations by large trans-Neptunian objects up to 2015

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