scholarly journals Analysis of Jupiter north equatorial belt hot spots in the 4-5 μm range from Galileo/near-infrared mapping spectrometer observations: Measurements of cloud opacity, water, and ammonia

1998 ◽  
Vol 103 (E10) ◽  
pp. 23023-23041 ◽  
Author(s):  
M. Roos-Serote ◽  
P. Drossart ◽  
T. Encrenaz ◽  
E. Lellouch ◽  
R. W. Carlson ◽  
...  
Keyword(s):  
Hot Spots ◽  
Near Infrared ◽  
Equatorial Belt

scholarly journals Hot spots on Io: Initial results from Galileo's near infrared mapping spectrometer

1997 ◽  
Vol 24 (20) ◽  
pp. 2439-2442 ◽  
Author(s):  
Rosaly Lopes-Gautier ◽  
A. G. Davies ◽  
R. Carlson ◽  
W. Smythe ◽  
L. Kamp ◽  
...  
Keyword(s):  
Hot Spots ◽  
Near Infrared ◽  
Initial Results

scholarly journals Galileo NIMS Observations of Io

2002 ◽  
Vol 12 ◽  
pp. 614-617
Author(s):  
Ashley Gerard Davies ◽  
Sylvain Douté
Keyword(s):  
Grain Size ◽  
Sulfur Dioxide ◽  
Hot Spots ◽  
Near Infrared ◽  
Volcanic Eruptions ◽  
Infrared Observations ◽  
Jovian Satellite

AbstractThe Near Infrared Mapping Spectometer (NIMS) on the Galileo spacecraft has been observing the volcanic Jovian satellite Io at regular intervals since June 1996. These infrared observations have allowed detailed mapping of the distribution and grain size of sulfur dioxide on Io’s surface, identification of volcanic centers, mapping of the distribution of hot spots, and investigations into the style and evolution of individual volcanic eruptions.

scholarly journals Near-Infrared View of the Nuclear Region of NGC 1808

1997 ◽  
Vol 159 ◽  
pp. 349-350
Author(s):  
J. K. Kotilainen
Keyword(s):  
Hot Spots ◽  
Near Infrared ◽  
Star Formation Rate ◽  
Hot Spot ◽  
Formation Rate ◽  
Line Emission ◽  
Continuum Emission ◽  
Starburst Galaxy ◽  
Nir Imaging ◽  
Red Supergiants

AbstractWe discuss NIR imaging of the starburst galaxy NGC 1808. The circumnuclear continuum emission shows no morphological change with wavelength and most of it is produced by an evolved bulge population, not by red supergiants or dust. The line emission arises from distinct hot spots. From comparison of Brγ and Hα fluxes, we derive extinction Av = 3–5 toward the hot spots. From modeling of the line and continuum luminosities, we derive a star-formation rate of 0.1–0.6 M⊙ yr–1 and SN rate ~ 0.4–11 × 10–3 yr–1 per hot spot. The age of the burst is 8–17 Myr for the hot spots and ~ 40 Myr for the nucleus. Finally, evidence for and against hidden Seyfert activity in NGC 1808 is discussed.

Cautionary Analysis of Spectral Radiance from Io’s Active Volcanoes Derived from Galileo Near-Infrared Mapping Spectrometer Data

2021 ◽  
Vol 163 (1) ◽  
pp. 2
Author(s):  
Ashley Gerard Davies
Keyword(s):  
Hot Spots ◽  
Near Infrared ◽  
Hot Spot ◽  
Spectral Radiance ◽  
Temperature Model ◽  
Multiple Orders ◽  
Unit Conversion ◽  
Spectrometer Data ◽  
Detector Saturation ◽  
Active Volcanoes

Abstract Between 1996 and 2001, the Galileo Near-Infrared Mapping Spectrometer (NIMS) obtained 190 observations of the volcanic Jovian moon Io. Rathbun et al. (2018) [Astron. J., 156, 207] published a list of 287 measurements of 3.5 μm spectral radiance from some of Io’s active volcanoes, derived from a subset of the NIMS data. However, the spectral radiances reported by Rathbun et al. are lower, in some cases by multiple orders of magnitude, than other analyses of the same observations and spectral radiances derived from contemporaneous ground-based data. In many cases, the Rathbun et al. hot-spot radiances are underreported by a factor of π, likely due to a mistake in unit conversion. For a small number of powerful hot spots, additional discrepancies appear to be the result of poor fits to data limited in wavelength range by NIMS detector saturation and a methodology that discards short-wavelength NIMS data that otherwise would have provided more robust temperature model fits.

Io's hot spots in the near-infrared detected by LEISA during the New Horizons flyby

2014 ◽  
Vol 119 (10) ◽  
pp. 2222-2238 ◽  
Author(s):  
Constantine C. C. Tsang ◽  
Julie A. Rathbun ◽  
John R. Spencer ◽  
Brigette E. Hesman ◽  
Oleg Abramov
Keyword(s):  
Hot Spots ◽  
Near Infrared ◽  
New Horizons

scholarly journals Multi-band high resolution spectroscopy rules out the hot Jupiter BD+20 1790b

2018 ◽  
Vol 613 ◽  
pp. A50 ◽  
Author(s):  
I. Carleo ◽  
S. Benatti ◽  
A. F. Lanza ◽  
R. Gratton ◽  
R. Claudi ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Hot Spots ◽  
Near Infrared ◽  
High Resolution Spectroscopy ◽  
Velocity Measurements ◽  
Stellar Activity ◽  
Multi Wavelength ◽  
First Time ◽  
Multi Band

Context. Stellar activity is currently challenging the detection of young planets via the radial velocity (RV) technique. Aims. We attempt to definitively discriminate the nature of the RV variations for the young active K5 star BD+20 1790, for which visible (VIS) RV measurements show divergent results on the existence of a substellar companion. Methods. We compare VIS data with high precision RVs in the near-infrared (NIR) range by using the GIANO–B and IGRINS spectrographs. In addition, we present for the first time simultaneous VIS-NIR observations obtained with GIARPS (GIANO–B and HARPS–N) at Telescopio Nazionale Galileo (TNG). Orbital RVs are achromatic, so the RV amplitude does not change at different wavelengths, while stellar activity induces wavelength-dependent RV variations, which are significantly reduced in the NIR range with respect to the VIS. Results. The NIR radial velocity measurements from GIANO–B and IGRINS show an average amplitude of about one quarter with respect to previously published VIS data, as expected when the RV jitter is due to stellar activity. Coeval multi-band photometry surprisingly shows larger amplitudes in the NIR range, explainable with a mixture of cool and hot spots in the same active region. Conclusions. In this work, the claimed massive planet around BD+20 1790 is ruled out by our data. We exploited the crucial role of multi-wavelength spectroscopy when observing young active stars: thanks to facilities like GIARPS that provide simultaneous observations, this method can reach its maximum potential.

scholarly journals Graphene-Based Spatial Light Modulator Using Metal Hot Spots

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3082 ◽  
Author(s):  
Zhanshan Sun ◽  
Yuejun Zheng ◽  
Yunqi Fu
Keyword(s):  
Electric Field ◽  
Hot Spots ◽  
Near Infrared ◽  
Modulation Depth ◽  
Field Enhancement ◽  
Spatial Light Modulators ◽  
Light Modulator ◽  
Light Modulators ◽  
High Modulation ◽  
Doped Graphene

Here, we report a graphene-based electric field enhancement structure achieved by several adjacent metal nanoribbons which form the hot spots of the electric field and thus promote the absorption of the single layered graphene below the hot spots. Based on the tunability of the graphene’s Fermi level, the absorption rate can be modulated from near 100% to 35% under low electrostatic gating, leading to a 20 dB modulation depth of reflectance. Compared with the existing near infrared spatial light modulators such as optical cavities integrated with graphene and other structures utilizing patterned or highly doped graphene, our design has the advantages of strong optical field enhancement, low power dissipation and high modulation depth. The proposed electro-optic modulator has a promising potential for developing optical communication and exploiting big data interaction systems.

scholarly journals High Resolution NIR Imaging of the Starburst Galaxy NGC 1808

1994 ◽  
Vol 159 ◽  
pp. 461-461
Author(s):  
L.E. Tacconi-Garman ◽  
A. Krabbe ◽  
A. Sternberg ◽  
R. Genzel
Keyword(s):  
Star Formation ◽  
Hot Spots ◽  
Active Sites ◽  
Near Infrared ◽  
Large Fraction ◽  
Line Emission ◽  
Far Infrared ◽  
Infrared Light ◽  
Continuum Emission ◽  
Starburst Galaxy

We report 0.6″ res. J, H, and K and 1.5″ res. imaging of 2.17 μm HI Brγ and 2.12 μm H2 1-0 S(1) line emission towards the nucleus of the starburst galaxy NGC 1808. In the K-band data we (partially) resolve the nucleus and see several small knots in the circumnuclear region. Further, our JHK continuum images show that a large fraction of the near infrared light in NGC 1808 is produced in young star forming clusters. The Brγ emission originates from a compact nuclear source and from several distinct emission knots in the circumnuclear region. These knots are spatially well correlated with a family of compact radio sources, but uncorrelated with the optical “hot spots”. We propose that the Brγ knots trace the actual sites of starburst activity, while the optical hot spots are just directions of low foreground extinction.We use our data together with radio and far-infrared continuum emission measurements to constrain the parameters of the individual starburst sites in NGC 1808. The data suggest that the starbursts are unsynchronized and prolonged (5 × 106–5 × 107 yrs). The star formation rates in the active sites range from ∼0.1 to ∼0.6 M⊙ yr−1, and the present rapid rate of star-formation in NGC 1808 can be maintained for at most another ∼7 × 107 yrs.Portions of this work are presently in press (Krabbe, Sternberg, and Genzel 1993), and a second paper is in preparation (Tacconi-Garman et al. 1993).

scholarly journals Simultaneous Visible and Near-Infrared Variability of Classical T Tauri Stars

2013 ◽  
Vol 8 (S299) ◽  
pp. 149-150
Author(s):  
Yukako Aimi ◽  
Misato Fukagawa ◽  
Tomonori Yasuda ◽  
Takuya Yamashita ◽  
Kouji Kawabata ◽  
...  
Keyword(s):  
Hot Spots ◽  
Structural Changes ◽  
Near Infrared ◽  
Protoplanetary Disks ◽  
Circumstellar Matter ◽  
T Tauri Stars ◽  
The Other ◽  
Stellar Systems ◽  
Be Stars ◽  
T Tauri

AbstractTemporal structural changes of protoplanetary disks surrounding T Tauri stars (TTSs) can cause magnitude variations of TTSs. On the other hand, variability is also expected due to cool spots and/or hot spots on the surface of the star, thus it is important to distinguish the causes of the observed variability. Our sample consists of 23 TTSs (22 classical T Tauri stars, 1 weak-lined T Tauri star) and 4 Herbig Ae/Be stars. The observations were performed over a period of about 3 months in the V, J, and KS band, simultaneously. We detected variability for all stars in the three bands (>0.05 mag in V, >0.09 mag in J, >0.09 mag in KS). Color-magnitude relations obtained between V, J, and KS bands suggest that stellar spots are not the only cause of variability for most of our targets. In addition, the data implies that six stellar systems contain larger grains than in the interstellar medium if the variability is only caused by extinction due to circumstellar matter.

scholarly journals Comparison of Radio and Optical Polarization in Extended Extragalactic Radio Sources: I. Observations

1990 ◽  
Vol 140 ◽  
pp. 449-450
Author(s):  
H.-J. Röser ◽  
K. Meisenheimer
Keyword(s):  
Spectral Index ◽  
Hot Spots ◽  
Near Infrared ◽  
Detailed Comparison ◽  
Radio Sources ◽  
Optical Polarization ◽  
Extragalactic Radio Sources ◽  
Flux Measurements ◽  
Synchrotron Light ◽  
Infrared Frequencies

We presented new observations in various wavebands of those extragalactic radio sources for which the emission of optical synchrotron light is established by polarimetric investigations (jets of M 87 and 3C 273, hot spots in the lobes of 3C 20, 3C 33 and Pictor A). In addition to optical spectral index and polarization maps, we collected flux measurements at radio, millimetre, and near-infrared frequencies. Our observations result in accurate synchrotron spectra between 109 and 1015 Hz. For some sources a detailed comparison between radio and optical polarization is possible.

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