HST imaging of Jupiter shortly after each impact: Plumes and fresh sites

During the first few hours after each impact, numerous phenomena were observed with telescopes on Earth, in orbit, and in space. The primary events in that time were: impacts themselves, rise and fall of large plumes of ejected material, and atmospheric waves; also of interest were the characteristic morphologies of fresh sites. Based on timing from Galileo instruments and ground-based observations, the Hubble Space Telescope (HST) recorded actual impact phenomena for fragments G and W, with the A and E impacts occurring just prior to the HST observation window. For these four events, plumes were directly imaged; plume development and collapse correlated with strong infrared emission near the jovian limb, supporting the interpretation that the IR brightness was created by the fall-back of plume material from high altitude (see chapter by Nicholson). For medium-to-large fresh impact sites imaged by HST within a few hours of impact, expanding rings were detected, caused by horizontal propagation of atmospheric waves (see chapters by Ingersoll and Zahnle). Initial site morphology at visible wavelengths was similar for all medium-to-large impacts: a dark streak surrounded by dark material, dominated by a large crescent-shaped ejecta to the southeast. Smaller impact sites typically only showed a dark patch (no ejecta) which dissipated quickly. This chapter summarizes the most recent measurements and interpretations of plumes and fresh impact sites as observed by HST.

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Detection and Characterization of earth-like Planets

International Astronomical Union Colloquium ◽

10.1017/s0252921100014810 ◽

1997 ◽

Vol 161 ◽

pp. 299-311 ◽

Cited By ~ 22

Author(s):

Jean Marie Mariotti ◽

Alain Léger ◽

Bertrand Mennesson ◽

Marc Ollivier

Keyword(s):

Direct Detection ◽

Contrast Ratio ◽

Angular Size ◽

Physical Nature ◽

Major Axis ◽

Infrared Emission ◽

Space Technology ◽

Semi Major Axis ◽

Earth Like Planets ◽

Visible Wavelengths

AbstractIndirect methods of detection of exo-planets (by radial velocity, astrometry, occultations,...) have revealed recently the first cases of exo-planets, and will in the near future expand our knowledge of these systems. They will provide statistical informations on the dynamical parameters: semi-major axis, eccentricities, inclinations,... But the physical nature of these planets will remain mostly unknown. Only for the larger ones (exo-Jupiters), an estimate of the mass will be accessible. To characterize in more details Earth-like exo-planets, direct detection (i.e., direct observation of photons from the planet) is required. This is a much more challenging observational program. The exo-planets are extremely faint with respect to their star: the contrast ratio is about 10−10at visible wavelengths. Also the angular size of the apparent orbit is small, typically 0.1 second of arc. While the first point calls for observations in the infrared (where the contrast goes up to 10−7) and with a coronograph, the latter implies using an interferometer. Several space projects combining these techniques have been recently proposed. They aim at surveying a few hundreds of nearby single solar-like stars in search for Earth-like planets, and at performing a low resolution spectroscopic analysis of their infrared emission in order to reveal the presence in the atmosphere of the planet of CO H2O and O3. The latter is a good tracer of the presence of oxygen which could be, like on our Earth, released by biological activity. Although extremely ambitious, these projects could be realized using space technology either already available or in development for others missions. They could be built and launched during the first decades on the next century.

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The need for a multi-purpose, optical–NIR space facility after HST and JWST

Experimental Astronomy ◽

10.1007/s10686-021-09732-w ◽

2021 ◽

Author(s):

Knud Jahnke ◽

Oliver Krause ◽

Hans-Walter Rix ◽

Frédéric Courbin ◽

Adriano Fontana ◽

...

Keyword(s):

Wavelength Range ◽

Hubble Space Telescope ◽

Hubble Constant ◽

White Paper ◽

Space Mission ◽

General Purpose ◽

List Type ◽

Space Telescope ◽

Readiness Level ◽

Visible Wavelengths

AbstractIn the early 2030s, after the end of operations for the epochal Hubble Space Telescope and the long-anticipated James Webb Space Telescope, astrophysics will lose access to a general purpose high-spatial resolution space observatory to cover the UV–optical–NIR wavelength range with a variety of imaging bandpasses and high-multiplexing mid-resolution spectroscopy. This will greatly impact astrophysical “discovery space” at visible wavelengths, in stark contrast to progress at most other wavelengths enabled by groundbreaking new facilities between 2010 and 2030. This capability gap will foreseeably limit progress in a number of fundamental research directions anticipated to be pressing in the 2030’s and beyond such as: What are the histories of star formation and cosmic element production in nearby galaxies? What can we learn about the nature of dark matter from dwarf galaxies? What is the local value of the Hubble Constant? A multi-purpose optical–NIR imaging and multiplexed spectroscopy Workhorse Camera (HWC) onboard NASA’s 4m-class Habitable Exoplanet Observatory (HabEx) space mission would provide access to these required data. HabEx is currently under study by NASA for the US Decadal Survey on Astronomy and Astrophysics 2020, and if selected would launch around 2035. Aside from its direct imaging of Earth-like exoplanets, it will have a general-observatory complement of instrumentation. The versatile Workhorse Camera will provide imaging and R$\sim $ ∼ 1000 spectroscopy from 370nm to 1800nm, diffraction-limited over the whole wavelength range, with simultaneous observations of the visible and NIR. Spectroscopic multiplexing will be achieved through microshutter arrays. All necessary HWC technology is already at Technology Readiness Level 5, hence technological risks are low. HWC has a rough-order-of-magnitude (ROM) cost of 300 M€, and could be European-funded within the cost envelope of an ESA S-class mission in the Voyage 2050 program, with matching funds by national funding agencies to construct HWC by a European instrument consortium. This White Paper is intended to put a European HabEx Workhorse Camera into ESA’s considerations. If ESA shares the wide interest and if HabEx were to be selected by NASA, there would be ample time to identify interested institutes for a European instrument consortium, including MPIA, to design, finance, and build the HabEx Workhorse Camera.

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Earth-based observations of impact phenomena

International Astronomical Union Colloquium ◽

10.1017/s0252921100115465 ◽

1996 ◽

Vol 156 ◽

pp. 81-109

Author(s):

Philip D. Nicholson

Keyword(s):

Hubble Space Telescope ◽

Common Pattern ◽

Mid Infrared ◽

Wide Range ◽

Impact Phenomena ◽

Infrared Wavelengths ◽

Positive Correlations ◽

The Individual ◽

The Impact ◽

Size Estimates

Earth-based observations at near- and mid-infrared wavelengths were obtained for at least 15 of the SL9 impacts, ranging from the spectacular G, K and L events to the barely-detected N and V impacts. Although there were a few exceptions, most of the IR lightcurves fit a common pattern of one or two relatively faint precursor flashes, followed several minutes later by the main infrared event as the explosively-ejected plume crashed down onto the jovian atmosphere. Correlations with the impact times recorded by the Galileo spacecraft and plumes imaged by the Hubble Space Telescope lead to an interpretation of the twin precursors in terms of (i) the entry of the bolide into the upper atmosphere, and (ii) the re-appearance of the rising fireball above Jupiter's limb. Positive correlations are observed between the peak IR flux observed during the splashback phase and both pre-impact size estimates for the individual SL9 fragments and the scale of the resulting ejecta deposits. None of the fragments observed to have moved off the main train of the comet by May 1994 produced a significant impact signature. Earth-based fireball temperature estimates are on the order of 750 K, 30-60 sec after impact. For the larger impacts, the unexpectedly protracted fireball emission at 2.3 μm remains unexplained. A wide range of temperatures has been inferred for the splashback phase, where shocks are expected to have heated the re-entering plume material at least briefly to several thousand K, and further modelling is required to reconcile these data.

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Direct Imaging of Circumstellar Disks in the Orion Nebula

International Astronomical Union Colloquium ◽

10.1017/s0252921100043177 ◽

1997 ◽

Vol 163 ◽

pp. 546-548

Author(s):

Mark J. McCaughrean

Keyword(s):

Near Infrared ◽

Hubble Space Telescope ◽

Circumstellar Disks ◽

Infrared Emission ◽

Orion Nebula ◽

Direct Imaging ◽

Stellar Photometry ◽

Inclination Angles ◽

Low Mass ◽

Lower Limits

AbstractWe present observations of the Orion Nebula made with the Hubble Space Telescope in which a number of stars are seen surrounded by dark silhouettes seen projected against the bright background HII region. We find a variety of morphologies, all consistent with thin circumstellar disks spanning a range of diameters (50 to 1000 AU) and inclination angles (0 to > 80 degrees). The silhouette intensity profiles cannot be fit by standard disk models in which the surface density follows a radial power law with an exponent in the range −0.75 to −1.5. Rather, the data are best fit by opaque inner disks with exponential edges, and we discuss possible physical origins of this apparent truncation. Masses in the range 6 × l026−4 × 1030 g (i.e., up to 0.002 M⊙) are determined for the disks by assuming that the faint light measured from them is background light transmitted through the disk. However, these are strict lower limits on the true disk masses, as most of this light can be accounted for by PSF blurring and scattering in the HST optical train; the present observations are in fact consistent with completely opaque disks. Central stars are seen directly in five of the silhouettes, while the presence of a star is inferred in the sixth, where small reflection nebulae are seen above and below the plane of the near edge-on disk. Optical and near-infrared stellar photometry is consistent with young (~ 1 Myr) low-mass (0.3−1.5 M⊙) stars, with several showing evidence for excess near-infrared emission from the disk inner edge. These direct imaging observations are discussed in the wider context of circumstellar disks in the Orion Nebula and Trapezium Cluster, additionally revealed as compact ionized nebulae (so-called “proplyds”) in the vicinity of the central OB stars, and via infrared (>2µm) excesses in stellar photometry. Overall, disks are found to be common in the cluster (>50% of all stars), implying that they can survive the rigours of life near massive stars.

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THE NEAR INFRARED SPECTRUM OF THE NIGHT AIRGLOW OBSERVED FROM HIGH ALTITUDE

Canadian Journal of Physics ◽

10.1139/p64-097 ◽

1964 ◽

Vol 42 (6) ◽

pp. 1037-1045 ◽

Cited By ~ 50

Author(s):

H. P. Gush ◽

H. L. Buijs

Keyword(s):

Infrared Spectrum ◽

Emission Spectrum ◽

High Altitude ◽

Electronic Transition ◽

Near Infrared ◽

Michelson Interferometer ◽

Infrared Emission ◽

Upper Atmosphere ◽

Transition Formula ◽

First Time

The infrared emission spectrum of the upper atmosphere between 1.2 and 2.5 microns has been measured at night by means of a Michelson interferometer carried to an altitude of 90,000 feet by a balloon. The complete Δν = 2 sequence of rotation–vibration OH bands has been observed at a resolution sufficient to resolve the rotational structure. The (0, 0) band of the electronic transition [Formula: see text] of oxygen at 1.27 microns has been observed in the night-sky spectrum for the first time. Its brightness is comparable with that of the (4, 2) OH band at 1.6 microns.

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THE DEEP BLUE COLOR OF HD 189733b: ALBEDO MEASUREMENTS WITH HUBBLE SPACE TELESCOPE /SPACE TELESCOPE IMAGING SPECTROGRAPH AT VISIBLE WAVELENGTHS

The Astrophysical Journal ◽

10.1088/2041-8205/772/2/l16 ◽

2013 ◽

Vol 772 (2) ◽

pp. L16 ◽

Cited By ~ 96

Author(s):

Thomas M. Evans ◽

Frédéric Pont ◽

David K. Sing ◽

Suzanne Aigrain ◽

Joanna K. Barstow ◽

...

Keyword(s):

Hubble Space Telescope ◽

Blue Color ◽

Space Telescope ◽

Deep Blue ◽

Visible Wavelengths ◽

Imaging Spectrograph

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Dust distribution and temperature in the Magellanic Clouds interstellar medium

Symposium - International Astronomical Union ◽

10.1017/s0074180900201034 ◽

1991 ◽

Vol 148 ◽

pp. 407-414 ◽

Cited By ~ 1

Author(s):

M. Sauvage ◽

L. Vigroux

Keyword(s):

Interstellar Dust ◽

Hubble Space Telescope ◽

Infrared Emission ◽

Magellanic Clouds ◽

Infrared Space Observatory ◽

Chemical Abundances ◽

The Galaxy ◽

Recent Developments ◽

Dust Composition ◽

Dust Distribution

This review deals with the various aspects of interstellar dust in the Magellanic Clouds (MCs). Dust properties can be traced from interstellar absorption, with an emphasis on UV properties, and from infrared emission. Thanks to IRAS, most of the recent developments in this field have been found in the infrared. The low resolution of IRAS was, in fact, well suited for MC mapping and these observations offer a unique opportunity to study the dust properties in various conditions of the Interstellar Radiation Field (ISRF) and of chemical abundances. The proximity of the MCs allows a direct study of the link between the stellar population and the dust properties via the ISRF. On the other hand, the comparison of IRAS data in the MCs and in the Galaxy allows us to study the dust composition for metallicity varying by a factor of 10. From these data and the previous results on UV absorption, it emerges that if the gas-to-dust ratio changes with metallicity, there is also a variation in the relative abundances of the dust components. In this review, we will also discuss how our knowledge of the MCs will be used to prepare for observations of more distant galaxies, with the next generation of space observatories such as the Hubble Space Telescope and the Infrared Space Observatory.

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Formation of Open Clusters

Symposium - International Astronomical Union ◽

10.1017/s0074180900091828 ◽

1980 ◽

Vol 85 ◽

pp. 169-190 ◽

Cited By ~ 2

Author(s):

G. Burki

Keyword(s):

Cluster Formation ◽

Spectral Energy Distribution ◽

Background Field ◽

Infrared Emission ◽

Open Clusters ◽

Spectral Energy ◽

Evolutionary Stage ◽

Radio Waves ◽

Interstellar Clouds ◽

Visible Wavelengths

A forming star progresses through several evolutionary stages which are marked by different observational signs that can be identified by different techniques. Stellar birth from interstellar matter occurs in dense, cold clouds of gas due to a local increase in the density and interstellar clouds composed of molecules and grains are the preferential place where star formation can be initiated. The observational indications of this prestellar stage are the emission of millimeter radio waves by the cloud's many molecules and the optical obscuration of the background field stars by the grains mixed with the molecular gas. When fragmentation and condensation mechanisms occur in a dense cloud, the gravitationally collapsing fragments cannot be directly observed at visible wavelengths, because their light is blocked by the dust grains which heat up and radiate in the infrared. Thus the various protostellar stages are essentially studied using infrared techniques. Evidently, the spectral energy distribution of the protostars depends on their evolutionary stage and, globally speaking, one can say that the maximum of the infrared emission moves towards the short infrared wavelengths as the protostar evolves. A tentative coherent stellar evolutionary scenario may be given for the radio and infrared sources directly connected with the star and cluster formation:

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