Related papers: Model for Atomic Oxygen Visible Line Emissions in …
The green (5577 \AA) and red-doublet (6300, 6364 \AA) lines are prompt emissions of metastable oxygen atoms in the $^1$S and $^1$D states, respectively, that have been observed in several comets. The value of intensity ratio of green to…
In comets the atomic oxygen green to red-doublet emission intensity ratio (G/R ratio) of 0.1 has been used to confirm H$_2$O as the parent species producing oxygen emission lines. The larger ($>$0.1) value of G/R ratio observed in a few…
To study the formation of the [OI] lines - i.e., 5577 A (the green line), 6300 A and 6364 A (the two red lines) - in the coma of comets and to determine the parent species of the oxygen atoms using the green to red-doublet emission…
Conventional narrowband photoelectric photometry of Comet Hale-Bopp (1995 O1) was obtained on 99 nights from mid-1995 to early-2000, yielding gas and dust production rates over an unprecedented range of time and distance. The appearance of…
We present a study of the three forbidden oxygen lines [OI] located in the optical region (i.e., 5577.339 \r{A} (the green line), 6300.304 \r{A} and 6363.776 \r{A} (the two red lines)) in order to better understand the production of these…
Based on long-slit infrared spectroscopic observations, it has been suggested that half of the carbon monoxide present in the atmosphere of comet C/1995 O1 (Hale-Bopp) close to perihelion was released by a distributed source in the coma,…
We report on the detection of atomic oxygen lines in the spectra of 8 comets. These forbidden lines are a result of the photodissociation of the parent oxygen-bearing species directly into an excited state. We used high resolution spectra…
Alice ultraviolet spectrometer onboard Rosetta space mission observed several spectroscopic emissions emanated from volatile species of comet 67P/Churyumov-Gerasimenko (hear after 67P/C-G) during its entire escorting phase. We have…
The N$_2$ and CO-rich and water-depleted comet C/2016 R2 (Pan-STARRS) (hereafter `C/2016 R2') is a unique comet for detailed spectroscopic analysis. We aim to explore the associated photochemistry of parent species, which produces different…
The abundance of CO2 in comets has been derived using CO Cameron band (a3pi --> X1Sigma+) emission assuming that photodissociative excitation of CO2 is the main production process of CO(a3pi). On comet 1P/Halley the Cameron (1-0) band has…
Observations of the CO J(1-0) 115 GHz and J(2-1) 230 GHz lines in comet C/1995 O1 (Hale-Bopp) were performed with the IRAM Plateau de Bure interferometer on 11 March, 1997. The observations were conducted in both single-dish (ON-OFF) and…
Remote observation of spectroscopic emissions is a potential tool for the identification and quantification of various species in comets. CO Cameron band (to trace \cod) and atomic oxygen emissions (to trace H$_2$O and/or CO$_2$, CO) have…
We report the discovery of X-ray emission from comet C/1995 O1 (Hale-Bopp) by the LECS instrument on-board BeppoSAX on 1996 September 10--11. The 0.1--2.0 keV luminosity decayed by a factor of 2 on a timescale of ~10 hr with a mean value of…
We present high-resolution optical spectroscopy of interstellar comet 3I/ATLAS (C/2025 N1) obtained with the High Dispersion Spectrograph mounted on the Subaru Telescope on UT 2026 January 7, when the comet was on its outbound trajectory at…
We present observations of rotational lines of H2S, SO and CS performed in comet C/1995 O1 (Hale-Bopp) in March 1997 with the Plateau de Bure interferometer (IRAM). The observations provide informations on the spatial and velocity…
Activity of most comets near the Sun is dominated by sublimation of frozen water, the most abundant ice in comets. Some comets, however, are active well beyond the water-ice sublimation limit of ~3 AU. Three bodies dominate the…
29P/Schwassmann-Wachmann 1 is a distant Centaur/comet, showing persistent CO-driven activity and frequent outbursts. We used the Herschel space observatory in 2010, 2011, and 2013 to observe H$_2$O and NH$_3$ and to image the dust coma.…
We report on high spectral resolution observations of comet C/1999 S4 (LINEAR) obtained at McDonald Observatory in June and July 2000. We report unequivocal detections of the O (1S) and O (1D) metastable lines in emission in the cometary…
Comet C/1995 O1 (Hale-Bopp) has provided an unprecedented opportunity to observe a bright comet over a wide range of heliocentric distances. We present here Spitzer Space Telescope observations of Hale-Bopp from 2005 and 2008 that show a…
We report results from broadband visible images of comet C/2012 S1 (ISON) obtained with the Hubble Space Telescope Wide Field Camera 3 on 2013 April 10. C/ISON's coma brightness follows a 1/{\rho} (where {\rho} is the projected distance…