michael mumma

University of Maryland, College Park, Maryland, Astronomy, Faculty Member

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Papers by michael mumma

Messengers from the Early Solar System - The Similarity and Diversity of Comets

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Messengers from the Early Solar System - Comets as Carriers of Cosmic Information

Viewed from a cosmic perspective, Earth is a dry planet yet its oceans are enriched in deuterium ... more Viewed from a cosmic perspective, Earth is a dry planet yet its oceans are enriched in deuterium by a large factor relative to nebular hydrogen. Can comets have delivered Earth's water? The question of exogenous delivery of water and organics to Earth and other young planets is of critical importance for understanding the origin of Earth's water, and for assessing the possible existence of exo-planets similar to Earth. Strong gradients in temperature and chemistry in the proto-planetary disk, coupled with dynamical models, imply that comets from the Oort Cloud and Kuiper Disk reservoirs should have diverse composition. The primary volatiles in comets (ices native to the nucleus) provide the preferred metric, and taxonomies based on them are now beginning to emerge [1, 2, 3]. The measurement of cosmic parameters such as the nuclear spin temperatures for H 2 O, NH 3 , and CH 4 , and of enrichment factors for isotopologues (D/H in water and hydrogen cyanide, 14 N/ 15 N in CN and hydrogen cyanide) provide additional important tests for the origin of cometary material. I will provide an overview of these aspects, and their implications for the origin of Earth's water and prebiotic organics.

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The Evolution of Volatile Production in Comet C/2009 P1 (Garradd) During Its 2011–2012 Apparition

The Astrophysical Journal, 2015

We report observations at millimeter and submillimeter wavelengths of comet C/2009 P1 (Garradd) f... more We report observations at millimeter and submillimeter wavelengths of comet C/2009 P1 (Garradd) from 2011 December 28 to 2012 April 24, using the Arizona Radio Observatory submillimeter telescope (SMT) and the James Clerk Maxwell Telescope (JCMT). Garradd is a dynamically young long-period comet from the Oort Cloud, with a periodicity of 127,000 years, that reached perihelion on 2011 December 23 (at R h = 1.55 AU and ∆ = 20.1 AU) and made its closest approach to the Earth on 2012 March 05 (at R h = 1.84 AU and ∆ = 1.26 AU). We obtained gas production rates, and molecular abundances relative to water for HCN, ortho-H 2 CO, CS, CO and CH 3 OH. A rotational temperature, T rot ≈ 50 K, was determined by observing multiple methanol lines with the JCMT. By averaging the abundance ratio relative to water from the SMT and the JCMT we derive: CO: 7.03 ± 1.84 %, HCN: 0.04 ± 0.01 %, o-H 2 CO: 0.14 ± 0.03 % as a parent molecule (and 0.28 ± 0.06 % as an extended source), CS: 0.03 ± 0.01 % and CH 3 OH: 3.11 +1.86 −0.51 %. We concluded that Garradd is normal in CH 3 OH, depleted in HCN, o-H 2 CO and CS and slightly enriched in CO with respect to typically observed cometary mixing ratios. We also studied the temporal evolution of HCN and CO and find that the production of HCN has a trend similar to water (but with short-term variation), with a decrease after perihelion, while that of CO shows contrary behavior: remaining constant or increasing after perihelion.

format_quoteGarradd exhibits a distinct pre-perihelion water peak and post-perihelion CO activity indicative of composition differences compared to other comets.format_quote

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The Volatile Composition of the Split Ecliptic comet 73P/Schwassmann-Wachmann 3: A Comparison of Fragments C and B

by michael mumma and Geoffrey Blake

Astrophysical Journal, 2006

The composition of fragments C and B of the Jupiter-family comet 73P/Schwassmann-Wachmann 3 (SW3)... more The composition of fragments C and B of the Jupiter-family comet 73P/Schwassmann-Wachmann 3 (SW3) was investigated in early April of 2006 at IR wavelengths using high-dispersion echelle spectroscopy. Both fragments were depleted in ethane, and C was depleted in most forms of volatile carbon. In particular, fragment C shows a severe depletion of CH 3 OH but a "normal" abundance of HCN (which has a similar volatility). Thermal processing is a possible explanation, but since fragment B is perhaps sublimating fresher material because of the frequent outbursts and fragmentation, the observed depletions might have cosmogonic implications. The chemistry of the volatile ices in SW3, like in the Oort Cloud comet C/1999 S4 (LINEAR), may be associated with sublimation of icy mantles from precometary grains followed by subsequent gas-phase chemistry and recondensation.

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Deep Impact: Observations from a Worldwide Earth-Based Campaign

by michael mumma, Roberto Vázquez, and M. Belton

Science, 2005

On 4 July 2005, many observatories around the world and in space observed the collision of Deep I... more On 4 July 2005, many observatories around the world and in space observed the collision of Deep Impact with comet 9P/Tempel 1 or its aftermath. This was an unprecedented coordinated observational campaign. These data show that (i) there was new material after impact that was compositionally different from that seen before impact; (ii) the ratio of dust mass to gas mass in the ejecta was much larger than before impact; (iii) the new activity did not last more than a few days, and by 9 July the comet's behavior was indistinguishable from its pre-impact behavior; and (iv) there were interesting transient phenomena that may be correlated with cratering physics.

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Carbon Monoxide Production and Excitation in Comet C/1995 O1 (Hale-Bopp): Isolation of Native and Distributed CO Sources

Icarus, 2001

The release of carbon monoxide from Comet C/1995 O1 Hale-Bopp was studied between June 1996 and S... more The release of carbon monoxide from Comet C/1995 O1 Hale-Bopp was studied between June 1996 and September 1997 using high resolution infrared spectroscopy near 4.7 µm. The excitation of CO molecules in the coma was assessed through measurement of the rotational temperature on several dates at an angular resolution of ∼1 arcsecond. An increase in T rot with distance from the nucleus was revealed, most likely because of photolytic heating by fast Hatoms. Observed temperature profiles varied from date to date, but overall the degree of heating was most pronounced near perihelion. The similar rotational temperatures observed for CO and HCN may indicate control of rotational populations by collisions with electrons.

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Infrared Spectroscopy of the ν 3 Band of Hydrogen Cyanide in Comet C/1995 O1 Hale–Bopp

Icarus, 1999

Hale-Bopp at infrared wavelengths near 3.0 µm on four dates between Feb 24.0 and May 1.0 1997 usi... more Hale-Bopp at infrared wavelengths near 3.0 µm on four dates between Feb 24.0 and May 1.0 1997 using high-resolution spectroscopy. The average rotational temperature retrieved for the (001) vibrational level on UT 1997 April 29.9 was (95 ± 6) K near the nucleus, increasing to (122 ± 8) K in the intermediate coma (4 -10 off the nucleus). The HCN production rate on April 29.9 was (3.09 ± 0.13) × 10 28 molecules s −1 . When compared with the water production rate obtained from direct measurements of the H 2 O 100-010 band on common observation dates using the same instrument and data processing algorithms, the weighted average (for the four dates) of the relative abundance (HCN/H 2 O) was (0.40 ± 0.05)%. The measured spatial distribution for HCN is consistent with its release at the nucleus-no significant contribution from a distributed source is required within 10,000 km of the nucleus.

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Comet outbursts and polymers of HCN

Astrophysical Journal, 1992

... Printed in USA COMET OUTBURSTS AND POLYMERS OF HCN TERRENCE W. RETTIG Department ofPhysics an... more

The effect of electron collisions on rotational populations of cometary water

Astrophysical Journal, 1992

The e-H2O collisional rate for exciting rotational transitions in cometary water is evaluated for... more The e-H2O collisional rate for exciting rotational transitions in cometary water is evaluated for conditions found in Comet Halley during the Giotto spacecraft encounter. In the case of the 0(00)-1(11) rotational transition, the e-H2O collisional rate exceeds that for excitation by neutral-neutral collisions at distances exceeding 3000 km from the cometary nucleus. The estimates are based on theoretical and experimental

Identification of two sources of carbon monoxide in comet Hale-Bopp

by michael mumma and Robert Novak

Nature, 1999

The composition of ices in comets may reflect that of the molecular cloud in which the Sun formed... more The composition of ices in comets may reflect that of the molecular cloud in which the Sun formed, or it may show evidence of chemical processing in the pre-planetary accretion disk around the proto-Sun. As carbon monoxide (CO) is ubiquitous in molecular clouds 1,2 , its abundance with respect to water could help to determine the degree to which pre-cometary material was processed, although variations in CO abundance may also be influenced by the distance from the Sun at which comets formed 3-5 . Observations have not hitherto provided an unambiguous measure of CO in the cometary ice (native CO). Evidence for an extended source of CO associated with comet Halley was provided by the Giotto spacecraft 6-9 , but alternative interpretations exist 10 . Here we report observations of comet Hale-Bopp which show that about half of the CO in the comet comes directly from ice stored in the nucleus. The abundance of this CO with respect to water (12 per cent) is smaller than in quiescent regions of molecular clouds, but is consistent with that measured in proto-stellar envelopes 11 , suggesting that the ices underwent some processing before their inclusion into Hale-Bopp. The remaining CO arises in the coma, probably through thermal destruction of more complex molecules.

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Identification of a new band system of isotopic CO 2 near 3.3 μm: Implications for remote sensing of biomarker gases on Mars

Icarus, 2008

... Geronimo L. Villanueva a , Corresponding Author Contact Information , 1 , E-mail The Correspo... more

Discovery of X-ray and Extreme Ultraviolet Emission from Comet C/Hyakutake 1996 B2

Science, 1996

... with the presence of a hot plasma, highly energetic particles, or with material optically thi... more

Spectroscopy of Comet Hyakutake at 80–700 A: First Detection of Solar Wind Charge Transfer Emissions

Astrophysical Journal, 2001

Spectra of comet Hyakutake at 80È700 observed with a resolving power of 10 reveal for the Ðrst A ... more Spectra of comet Hyakutake at 80È700 observed with a resolving power of 10 reveal for the Ðrst A time the emission lines of multiple-charged ions that are brought to the comet by the solar wind and excited in charge exchange with cometary neutral species. The most prominent lines are O4`j215, C4j 249, and He`j304. Some other lines, which are of comparable strength, are blended. The results convincingly prove that the charge exchange mechanism is the dominant process in excitation of X-ray and EUV emissions from comets. The He`line at 304 is emitted in a similar process by the solar wind A a-particles. The quantum yield of charge exchange is B4 photons per heavy ion in collisionally thick parts of comae, and the photon luminosity of charge exchange at energy below 100 eV exceeds that above 100 eV by a factor of 2. However, the energetic luminosity below 100 eV is smaller than that above 100 eV by a factor of 2. The O`lines at 538/539, 617, and 430/442 are formed by photoioniza-A tion of atomic oxygen similarly to those in EarthÏs dayglow. The observed depletion of neon relative to the solar abundance by more than a factor of 2600 conÐrms the current view that Oort cloud comets formed in the Jupiter-Neptune region of the solar nebula.

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Mapping of Ozone and Water in the Atmosphere of Mars near the 1997 Aphelion

Icarus, 2002

We present absolute abundances and latitudinal variations of ozone and water in the atmosphere of... more We present absolute abundances and latitudinal variations of ozone and water in the atmosphere of Mars during its late northern spring (L s = 67.3 • ) shortly before aphelion. Long-slit maps of the a 1 g state of molecular oxygen (O 2 ) and HDO, an isotopic form of water, were acquired on UT January 21.6 1997 using a highresolution infrared spectrometer (CSHELL) at the NASA Infrared Telescope Facility. O 2 (a 1 g ) is produced by ozone photolysis, and the ensuing dayglow emission at 1.27 µm is used as a tracer for ozone. Retrieved vertical column densities for ozone above ∼20 km ranged between 1.5 and 2.8 µm-atm at mid-to low latitudes (30 • S-60 • N) and decreased outside that region. A significant decrease in ozone density is seen near 30 • N (close to the subsolar latitude of 23.5 • N). The rotational temperatures retrieved from O 2 (a-X) emissions show a mean of 172 ± 2.5 K, confirming that the sensed ozone lies in the middle atmosphere (∼24 km). The ν 1 fundamental band of HDO near 3.67 µm was used as a proxy for H 2 O. The retrieved vertical column abundance of water varies from 3 precipitable microns (pr-µm) at ∼30 • S to 24 pr-µm at ∼60 • N. We compare these results with current photochemical models and with measurements obtained by other methods. c 2002 Elsevier Science (USA)

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Absolute wind velocities in the lower thermosphere of Venus using infrared heterodyne spectroscopy

Icarus, 1991

... is consistent with the Bougher et al. (1986, 1988) two-and three-dimensional hydro-dynamical ... more

Carbonyl Sulfide in Comets C/1996 B2 (Hyakutake) and C/1995 O1 (Hale–Bopp): Evidence for an Extended Source in Hale–Bopp

by michael mumma and Karen Magee-sauer

Icarus, 1998

Analyses of dust in Comet 1P/Halley and comparison O1) using high dispersion infrared spectroscop... more Analyses of dust in Comet 1P/Halley and comparison O1) using high dispersion infrared spectroscopy at the NASA with possible sulfur compounds in cometary ice (e.g., H 2 S, Infrared Telescope Facility on Mauna Kea, Hawaii. Six lines (P10, P11, P12, P14, P15, and P17) of the 3 fundamental band CS 2 , and OCS) demonstrated that most sulfur is contained near 4.85 m were detected on UT April 16.0, April 30.0, and in the refractory CHON grains (Mumma et al. 1993, May 1.2, 1997, and two additional lines (P18 and P22) were Delsemme 1991, Jessberger and Kissel 1991, Jessberger et detected on April 30.0. Water was detected directly through al. 1988). About 10% of cometary sulfur may reside in the emission lines of its 1 -2 hot band on UT April 16.0, April ice, with the sulfuretted ices together comprising ȁ0.5% 30.0, and May 1.2, with a rotational temperature of abundance relative to water (Meier and A'Hearn 1997, 93 ؎ 16 K on May 1.2. Adopting a rotational temperature of Roettger 1991). Since ices are more easily modified than 100 K for OCS, our derived production rates are (3.80 ؎ 0.67) are refractory grains, the present sulfur chemistry may and (1.77 ؎ 0.85) ؋ 10 28 molecules s ؊1 on April 16.0 and May 1.2, respectively. The measured production rates imply mixing reveal much about the origins of these ices and their subseratios (Q OCS /Q H 2 O ) of (4.58 ؎ 0.77) and (2.76 ؎ 1.34) ؋ 10 ؊3 on quent processing history. The determination of the sulfur April 16.0 and May 1.2, respectively. Comparison of spatial inventory in comets is thus an important piece to the puzzle profiles for OCS, H 2 O, and the dust continuum derived from of cometary origins. spectra taken less than 1 h apart suggests that on April 16.0 Molecular chemistry in dense interstellar cloud cores a significant amount of OCS (ȁ70% of the total) was released suggests several possible sources of volatile sulfur in comas an extended source. On April 30.0 and May 1.2 the quality ets, including H 2 S, H 2 CS, SO 2 , and OCS. These should be of the data prevent a firm conclusion regarding an extended present in cometary nuclei if they formed from icy-mantled source contribution. If the nature of the OCS source did not change between April 16.0 and May 1.2, the weighted mean interstellar grains as was inferred for Hyakutake (Mumma mixing ratio is (4.13 ؎ 0.77) ؋ 10 ؊3 . We searched for lines P1 1996, Greenberg 1982). H 2 S was first detected at radio through P8 of the 3 band of OCS in Comet Hyakutake frequencies in Comet Austin 1989c1 (Colom et al. 1990) (C/1996 B2) on UT March 24.5, 1996. Our upper limit (3) and Comet Levy 1990c (Bockelee-Morvan et al. 1990), for the OCS production rate in Hyakutake is 1.0 ؋ 10 27 moleboth with abundances ȁ2 ϫ 10 Ϫ3 relative to water. It was cules s ؊1 (Q OCS /Q H 2 O Ͻ 5.3 ؋ 10 ؊3 ).

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Reservoirs for Comets: Compositional Differences Based on Infrared Observations

Space Science Reviews, 2008

Tracing measured compositions of comets to their origins continues to be of keen interest to come... more Tracing measured compositions of comets to their origins continues to be of keen interest to cometary scientists and to dynamical modelers of Solar System formation and evolution. This requires building a taxonomy of comets from both present-day dynamical reservoirs: the Kuiper Belt (hereafter KB), sampled through observation of ecliptic comets (primarily Jupiter Family comets, or JFCs), and the Oort cloud (OC), represented observationally by the long-period comets and by Halley Family comets (HFCs). Because of their short orbital periods, JFCs are subjected to more frequent exposure to solar radiation compared with OC comets. The recent apparitions of the JFCs 9P/Tempel 1 and 73P/Schwassmann-Wachmann 3 permitted detailed observations of material issuing from below their surfaces—these comets added significantly to the compositional database on this dynamical class, which is under-represented in studies of cometary parent volatiles. This chapter reviews the latest techniques developed for analysis of high-resolution spectral observations from ∼2–5 μm, and compares measured abundances of native ices among comets. While no clear compositional delineation can be drawn along dynamical lines, interesting comparisons can be made. The sub-surface composition of comet 9P, as revealed by the Deep Impact ejecta, was similar to the majority of OC comets studied. Meanwhile, 73P was depleted in all native ices except HCN, similar to the disintegrated OC comet C/1999 S4 (LINEAR). These results suggest that 73P may have formed in the inner giant planets’ region while 9P formed farther out or, alternatively, that both JFCs formed farther from the Sun but with 73P forming later in time.

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Ground-based infrared measurements of the global distribution of ozone in the atmosphere of Mars

Icarus, 1991

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Systematic Observations of Methanol and Other Organics in Comet P/Swift-Tuttle: Discovery of New Spectral Structure at 3.42 μm

Icarus, 1995

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Water production and release in Comet 153P/Ikeya–Zhang (C/2002 C1): accurate rotational temperature retrievals from hot-band lines near 2.9-μm

by Jonathan Tennyson and michael mumma

Icarus, 2004

Multiple non-resonance fluorescence lines of water (H 2 O) were detected in Comet 153/P Ikeya-Zha... more Multiple non-resonance fluorescence lines of water (H 2 O) were detected in Comet 153/P Ikeya-Zhang (2002 C1) between UT 2002 March 21.9 (R h = 0.51 AU) and April 13.9 (R h = 0.78 AU), using the Cryogenic Echelle Spectrometer (CSHELL) at the NASA Infrared Telescope Facility. Analysis of 2.9-µm water lines enabled accurate determination of rotational temperatures on three dates. The derived H 2 O rotational temperatures were 138 +6 −5 , 141 +10 −9 , and 94 ± 3 K on UT 2002 March 22.0, March 23.0, and April 13.8, respectively. Water production rates were retrieved from spectral lines measured in nineteen separate grating settings over seven observing periods. The derived heliocentric dependence of the water production rate was Q = (9.2 ± 1.1) × 10 28 [R (−3.21±0.26) h ] molecules s −1 . The spatial distribution of H 2 O in the coma was consistent with its release directly from the nucleus (as a native source) on all dates.

format_quoteDerived H2O rotational temperatures were 138 ± 6 K, 141 ± 10 K, and 94 ± 3 K from March 22 to April 13, indicating cooling as the comet recedes from the Sun.format_quote

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