Spectra of comet C/2002 T7 (LINEAR)

We present the results of spectral observations of comet C/2002 T7 (LINEAR) carried out at the 1-m Zeiss-1000 telescope of the Special Astrophysical Observatory (Russia). The spectra were obtained within the 3500-7500 Å wavelength range on November 13, 14, and 21, 2003, before the perihelion passage, when heliocentric and geocentric distances of the comet were about 2.7 AU and 1.8 AU, respectively. Spectra do not show any emission features from the strongest cometary emissions of the CN, C2, and C3 molecules. The normalised spectral gradient of reflectivity is 2.8% per 1000 Å and 5.4% per 1000 Å for November 14 and 21, respectively. The Afρ parameter, which characterises the dust production rate in the comet, is on average about 800 cm. Comet C/2002 T7 (LINEAR) can be classified as belonging to the group of dusty comets

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523676 (2013 UL10): the first active red centaur

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731224 ◽

2018 ◽

Vol 620 ◽

pp. A93 ◽

Cited By ~ 1

Author(s):

E. Mazzotta Epifani ◽

E. Dotto ◽

S. Ieva ◽

D. Perna ◽

P. Palumbo ◽

...

Keyword(s):

Production Rate ◽

Canary Islands ◽

Colour Index ◽

Nucleus Size ◽

Dust Production ◽

La Palma ◽

Upper Limit ◽

Nucleus Surface ◽

Perihelion Passage

Aims. We present observations of 523676 (2013 UL10), a centaur orbiting between Jupiter and Uranus that is dynamically similar to the few tens of active centaurs that are currently known. Methods. We analysed visible BVR images of the centaur obtained at the Telescopio Nazionale Galileo (La Palma, Canary Islands, Spain) to investigate the weak comet-like activity and to derive information on the nucleus surface colours and size. Results. Centaur 523676 (2013 UL10) is the only centaur known so far that has both comet-like activity and red surface colours: its nucleus has a colour index [B – R] = 1.88 ± 0.11. The nucleus R magnitude (R = 20.93 ± 0.09) allowed us to derive an upper limit for its nucleus size of D ≤ 10 km. We estimated its dust production rate to be Qd ~ 10 kg s−1 at 6.2 au (just after its perihelion passage), resulting in a timescale for the surface blanketing process τB of approximately tens of years, which is very short with respect to typical dynamical lifetime inside the group. Future monitoring of 523676 (2013 UL10) is needed to further constrain the blanketing model for active centaurs and its timescale.

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Narrow-band photometry of Long Period Comets with TRAPPIST telescopes in 2019-2020

10.5194/epsc2020-419 ◽

2020 ◽

Author(s):

Youssef Moulane ◽

Emmanuel Jehin ◽

Francisco José Pozuelos ◽

Jean Manfroid ◽

Zouhair Benkhaldoun ◽

...

Keyword(s):

Solar System ◽

Production Rate ◽

Heliocentric Distance ◽

Narrow Band ◽

Maximum Activity ◽

The Sun ◽

Water Production ◽

Dust Production ◽

Long Period ◽

Water Production Rate

Long Period Comets (LPCs) have orbital periods longer than 200 years, perturbed from their resting place in the Oort cloud. Such gravitational influences may send these icy bodies on a path towards the center of the Solar system in highly elliptical orbits. In this work, we present the activity and composition evolution of several LPCs observed with both TRAPPIST telescopes (TS and TN) during the period of 2019-2020. These comets include: C/2017 T2 (PANSTARRS), C/2018 Y1 (Iwamoto), C/2018 W2 (Africano), and disintegrated comet C/2019 Y4 (ATLAS). We monitored the OH, NH, CN, C2 and C3 production rates evolution and their chemical mixing ratios with respect to their distances to the Sun as well as the dust production rate proxy (A(0)fp) during the journey of these comets into the inner Solar system. C/2017 T2 (PANSTARRS) is a very bright comet which was discovered on October 2, 2017 when it was 9.20 au from the Sun. We started observing this comet with TS at the beginning of August 2019 when it was at 3.70 au. The comet made the closest approach to the Earth on December 28, 2019 at a distance of 1.52 au and it passed the perihelion on May 4, 2020 at 1.61 au. The water production rate of the comet reached a maximum of (4,27&#177;0,12)1028 molecules/s and its dust production rate (A(0)fp(RC)) also reached the peak of 5110&#177;25 cm on January 26, 2020, when the comet was at 2.08 au from the Sun (-100 days pre-perihelion). At the time of writing, we still monitoring the activity of the comet with TN at heliocentric distance of 1.70 au. Our observations show that C/2017 T2 is a normal LPC. C/2018 Y1 (Iwamoto) is a nearly parabolic comet with a retrograde orbit discovered on December 18, 2018 by Japanese amateur astronomer Masayuki Iwamoto. We monitored the activity and composition of Iwamoto with both TN and TS telescopes from January to March 2019. The comet reached its maximum activity on January 29, 2019 when it was at 1.29 au from the Sun (-8 days pre-perihelion) with Q(H2O)=(1,68&#177;0,05)1028 molecules/s and A(0)fp(RC)= 92&#177;5 cm. These measurements show that it was a dust-poor comet compared to the typical LPCs. C/2018 W2 (Africano) was discovered on November 27, 2018 at Mount Lemmon Survey with a visual magnitude of 20. The comet reached its perihelion on September 6, 2019 when it was at 1.45 au from the Sun. We monitored the comet from July 2019 (rh=1.71 au) to January 2020 (rh=2.18 au) with both TN and TS telescopes. The comet reached its maximum activity on September 21, 15 days post-perihelion (rh=1.47 au) with Q(H2O)=(0,40&#177;0,03)1028 molecules/s. C/2019 Y4 (ATLAS) is a comet with a nearly parabolic orbit discovered on December 18, 2019 by the ATLAS survey. We started to follow its activity and composition with broad- and narrow-band filters with the TN telescope on February 22, 2019 when it was at 1.32 au from the Sun until May 3, 2020 when the comet was at a heliocentric distance of 0.90 au inbound. The comet activity reached a maximum on March 22 (rh=1.65 au) 70 days before perihelion. At that time, the water-production rate reached (1,53&#177;0,04)1028 molecules/s and the A(0)fp reached (1096&#177;14) cm in the red filter. After that, the comet began to fade and disintegrated into several fragments.

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Detection of a repeated transit signature in the light curve of the enigma star KIC 8462852: A possible 928-day period

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731306 ◽

2017 ◽

Vol 608 ◽

pp. A132 ◽

Cited By ~ 5

Author(s):

F. Kiefer ◽

A. Lecavelier des Étangs ◽

A. Vidal-Madjar ◽

G. Hébrard ◽

V. Bourrier ◽

...

Keyword(s):

Light Curve ◽

Production Rate ◽

A Priori ◽

Ring System ◽

Striking Similarity ◽

Dust Production ◽

High Quality ◽

Bad Weather ◽

Absorption Features

As revealed by its peculiar Kepler light curve, the enigmatic star KIC 8462852 undergoes short and deep flux dimmings at a priori unrelated epochs. This star presents nonetheless all other characteristics of a quiet 1 Gyr old F3V star. These dimmings resemble the absorption features expected for the transit of dust cometary tails. The exocomet scenario is therefore most commonly advocated. We reanalysed the Kepler data and extracted a new high-quality light curve to allow for the search of shallow signatures of single or a few exocomets. We discovered that among the 22 flux dimming events that we identified, two events present a striking similarity. These events occurred 928.25 days apart and lasted for 4.4 days with a drop in the star brightness by 1000 ppm. We show that the light curve of these events is well explained by the occultation of the star by a giant ring system or by the transit of a string of half a dozen exocomets with a typical dust production rate of 105–106 kg s-1. Assuming that these two similar events are related to the transit of the same object, we derive a period of 928.25 days. The following transit was expected in March 2017 but bad weather prohibited us from detecting it from ground-based spectroscopy. We predict that the next event will occur between 3−8 October 2019.

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Estimating the dust production rate of carbon stars in the Small Magellanic Cloud

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stx2641 ◽

2017 ◽

Vol 473 (4) ◽

pp. 5492-5513 ◽

Cited By ~ 22

Author(s):

Ambra Nanni ◽

Paola Marigo ◽

Léo Girardi ◽

Stefano Rubele ◽

Alessandro Bressan ◽

...

Keyword(s):

Production Rate ◽

Magellanic Cloud ◽

Small Magellanic Cloud ◽

Carbon Stars ◽

Dust Production

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Comet Kohoutek: Ground and Airborne High Resolution Tilting Filter IR Photometry

International Astronomical Union Colloquium ◽

10.1017/s025292110050102x ◽

1976 ◽

Vol 25 (Part1) ◽

pp. 357-360

Author(s):

C. Barbieri ◽

C. B. Cosmovici ◽

S. Drapatz ◽

K. W. Michel ◽

T Nishimura ◽

...

Keyword(s):

High Resolution ◽

Production Rate ◽

Near Infrared ◽

Gas Production ◽

Volatile Components ◽

The Sun ◽

Dust Production ◽

Production Rates ◽

Fabry Perot ◽

Vibration Rotation

AbstractBecause of Comet Kohoutek's anticipated large gas production, which seemed to offer a unique chance to reveal parent molecules, two Fabry-Perot Tilting Filter Photometers were designed with the purpose to detect and study the behaviour of CH4 and its photolysis product H2 The importance of these two molecules is well known and their detection would have given valuable indications about the structure of the nucleus, its thermal history and conditions of formation.Similar to CH4, H2 has no dipole moment and cannot be detected by radioastronomy. The most obvious way for measuring H2 in extended cometary comae is certainly on the basis of fluorescence from the Lyman bands around 1000Å, there are, however, vibrational quadrupole transitions within the overtone bands of the ground electronic state which give rise to emissions in the near infrared, accessible by means of ground based telescopes. Three of the stronger lines are: λ = 0.8748 μ; 0.8560 μ and 0.8497 μ. Methane is more readily detectable in the infrared, since it has strong fundamental (1-0) infrared vibration rotation bands at 3.3 μ (ν3).In order to measure both the CH4 concentration and its rotational temperature, a. very high resolution (~3.7A) high throughput instrument was designed which could isolate several individual vibration-rotation lines in the v3 band, namely the P2, P3 and P9 lines. The instrument consisting of a Fabry-Periot Tilting Filter Photometer with InSb detector interfaced with the 30 cm f/30 Dahl-Kirkham Telescope is described in detail elsewhere.( l). The observations were made in January from the NASA Convair 990 (Galileo II) at an altitude of 13 km, where atmospheric methane absorption can be minimized but not avoided. Doppler shift of cometary and atmospheric lines with respect to one another by at least a few A caused by the orbiting velocity of the comet would be sufficient to allow for high transmission measurements. Though long integration time measurements with Lock-In- Amplifier technique have been carried out, no signals from the CH4-rotational lines of the comet coma could be detected. Using the planet Venus as a calibration source for the photon flux and as a result of delicate laboratory measnrements an upper limit ofcould be derived. This value is several orders of magnitude less than the original predictions for Kohoutek during close approach. Therefore, one could conclude that volatile components like CH4 boiled off the comet well before perihelion, at large (~4 AU) distances from the sun and were responsible for the high brightness of the comet at that time. Such a fractionation is only possible if the nucleus was composed of relatively loose, porous ice, rather than compact ice. This hypothesis was strongly supported by the second experiment for search of H2 in the near infrared at the 182 cm telescope of Asiago. Also in this case a Fabry-Perot tilting filter photometer was designed to match with the f/9 optics of the telescope. The instrument (2) consists in a high resolution (~0.7A) tilting filter system with photon counting technique which allows phase-sensitive background subtraction. On the basis of the best data achieved between January 10 and 15 the occurrence of H2-lines with an intensity larger than 2% of the continuum could be excluded, viz. the flux averaged over the field of view was less than 4.105 photons/cm2 sec sr A. Since the pre- and post-perihelion measurements were not affected by molecular fluorescence, they represent only the light scattering flux from dust particles. The data display that the comet's dust coma was definitely brighter during approach than during recession from the sun. However, the quantity of more fundamental interest is the difference in dust production rates, and a derivation of the mass-production rate of dust could be derived. The study shows that both the dust and gas production rate differ greatly in the pre-perihelion period as compared to the post-perihelion period, as conjectured previously for "virgin" comets. (Dust production rate/gas production rate: pre-perihelion 0.1, post-perihelion 1). The pronounced asymmetry in the production rates strongly suggests that fractionation and dust entrainment effects have to be considered in brightness predictions of young comets, the nucleus of which will generally consist of a multi-component mixture of parent molecules.

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Modelling gas and dust around carbon stars in the Large Magellanic Cloud

Proceedings of the International Astronomical Union ◽

10.1017/s1743921318006944 ◽

2018 ◽

Vol 14 (S343) ◽

pp. 504-505

Author(s):

Sundar Srinivasan ◽

I.-K. Chen ◽

P. Scicluna ◽

J. Cami ◽

F. Kemper

Keyword(s):

Production Rate ◽

Strong Correlation ◽

Column Density ◽

Preliminary Investigation ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Carbon Stars ◽

Molecular Absorption ◽

Dust Production ◽

Absorption Features

AbstractIn order to investigate the effect of dust production on the molecular absorption, we model the dust continuum and the 7.5 and 13.7 μm acetylene absorption features in the Spitzer IRS spectra of 148 carbon stars in the Large Magellanic Cloud (LMC). Our preliminary investigation does not find a strong correlation between the dust-production rate and the column density of acetylene for the LMC sample. However, we will construct more models at high optical depths and probe a larger range of dust properties for more robust results.

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Correlation analysis of three influencing factors and the dust production rate for a free-falling particle stream

Particuology ◽

10.1016/j.partic.2017.03.003 ◽

2017 ◽

Vol 34 ◽

pp. 126-133 ◽

Cited By ~ 4

Author(s):

Mengjie Duan ◽

Yi Wang ◽

Xiaofen Ren ◽

Xinrui Qu ◽

Yingxue Cao ◽

...

Keyword(s):

Correlation Analysis ◽

Production Rate ◽

Influencing Factors ◽

Dust Production ◽

Particle Stream ◽

Free Falling

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The dust and gas environment of comet 8P/Tuttle

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab2609 ◽

2021 ◽

Vol 508 (2) ◽

pp. 1719-1731

Author(s):

Pedro J Gutiérrez ◽

Luisa M Lara ◽

Fernando Moreno

Keyword(s):

Monte Carlo ◽

Infrared Images ◽

Dust Production ◽

Production Rates ◽

Visible Spectra ◽

Dust Tail ◽

Gas Ratio ◽

Water Ratio ◽

High Dust ◽

Perihelion Passage

ABSTRACT Comet 8P/Tuttle has been selected as a possible backup target for the Comet Interceptor mission (ESA). This comet was observed intensively during its previous perihelion passage, in 2008 January. From those observations, important information was obtained about the physical properties of the nucleus and coma. This study focuses on the coma of 8P/Tuttle using visible spectra and images to derive gas and dust production rates. The production rates obtained suggest that this comet can be considered as ‘typical’ concerning the C2/CN and C3/CN ratios, although, depending on the criteria adopted, it could be defined as C3 depleted. NH2 production rates suggest an enrichment of this molecule. Visible and infrared images have been analysed using a Monte Carlo dust tail model. At comparatively large heliocentric distances, the coma is characterized by a dust-to-water ratio around or less than 1. Nevertheless, when the comet approaches perihelion, and the subsolar latitude crosses the equator, the coma dust-to-water ratio increases significantly, reaching values larger than six. Such a high dust-to-gas ratio around perihelion suggests that the nucleus of 8P/Tuttle is also ‘typical’ regarding the refractory content, considering the comparatively high values of that magnitude estimated for different comets.

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