LABORATORY STUDY OF THE IR SPECTRA OF METHANE ICES IN THE POLAR ENVIRONMENT
Section: STARS AND THE INTERSTELLAR MEDIUM
Authors:
1.
Ural Federal University
2.
Ural Federal University
3.
Ural Federal University
4.
Ural Federal University
5.
Ural Federal University
Type:
Сonference article
Published:
27.12.2024
Subject area:
VAC 1 Естественные науки
UDK 52 Астрономия. Геодезия
UDK 53 Физика
UDK 520 Инструменты, приборы и методы астрономических наблюдений, измерений и анализа
UDK 521 Теоретическая астрономия. Небесная механика. Фундаментальная астрономия. Теория динамической и позиционной астрономии
UDK 523 Солнечная система
UDK 524 Звезды и звездные системы. Вселенная Солнце и Солнечная система
UDK 52-1 Метод изучения
UDK 52-6 Излучение и связанные с ним процессы
GRNTI 41.00 АСТРОНОМИЯ
GRNTI 29.35 Радиофизика. Физические основы электроники
GRNTI 29.31 Оптика
GRNTI 29.33 Лазерная физика
GRNTI 29.27 Физика плазмы
GRNTI 29.05 Физика элементарных частиц. Теория полей. Физика высоких энергий
OKSO 03.06.01 Физика и астрономия
OKSO 03.05.01 Астрономия
OKSO 03.04.03 Радиофизика
BBK 2 ЕСТЕСТВЕННЫЕ НАУКИ
BBK 223 Физика
TBK 614 Астрономия
TBK 6135 Оптика
BISAC SCI004000 Astronomy
BISAC SCI005000 Physics / Astrophysics
UDK 52 Астрономия. Геодезия
UDK 53 Физика
UDK 520 Инструменты, приборы и методы астрономических наблюдений, измерений и анализа
UDK 521 Теоретическая астрономия. Небесная механика. Фундаментальная астрономия. Теория динамической и позиционной астрономии
UDK 523 Солнечная система
UDK 524 Звезды и звездные системы. Вселенная Солнце и Солнечная система
UDK 52-1 Метод изучения
UDK 52-6 Излучение и связанные с ним процессы
GRNTI 41.00 АСТРОНОМИЯ
GRNTI 29.35 Радиофизика. Физические основы электроники
GRNTI 29.31 Оптика
GRNTI 29.33 Лазерная физика
GRNTI 29.27 Физика плазмы
GRNTI 29.05 Физика элементарных частиц. Теория полей. Физика высоких энергий
OKSO 03.06.01 Физика и астрономия
OKSO 03.05.01 Астрономия
OKSO 03.04.03 Радиофизика
BBK 2 ЕСТЕСТВЕННЫЕ НАУКИ
BBK 223 Физика
TBK 614 Астрономия
TBK 6135 Оптика
BISAC SCI004000 Astronomy
BISAC SCI005000 Physics / Astrophysics
Language:
English
Keywords:
ISM: molecules, clouds, lines and bands; infrared: ISM; methods: laboratory: solid state; astrochemistry
Abstract (English):
We grew the pure methane ice and mixed binary ices of methane with polar molecules: water, carbon dioxide, methanol and ammonia under ultrahigh vacuum cryogenic conditions similar to those in cold prestellar clouds. The composition of ices was chosen to reflect current astrochemical notions. The following interstellar ice analogues were obtained: H$_2$O : CH$_4$ = 10 : 1, CO$_2$ : CH$_4$ = 5 : 1, CH$_3$OH : CH$_4$ = 2 : 1, NH$_3$ : CH$_4$ = 1 : 1, that are new to the literature and infrared spectra ice analogues databases. We report the significance of deposition temperature for the internal structure of ices, which gets revealed on infrared spectra during the warm up for ices deposited at 6.7 K and 10 K. We link the observed differences to solid methane being in amorphous phase ($T < 9.3$ K) and low-temperature crystalline (9.3 K $ < T < 20$ K) phases. We also note that the direct comparison between laboratory and observational spectra is possible since the deformation mode line shape doesn't depend on the grain size or shape near 7.7 $\mu$m, only on the temperature and molecular environment. Solid methane is a fairly abundant molecule in prestellar objects. With the James Webb Space Telescope (JWST) launch the quality of spectra has risen significantly and we hope that this work will be an asset to assigning the methane component in star-forming regions.
We grew the pure methane ice and mixed binary ices of methane with polar molecules: water, carbon dioxide, methanol and ammonia under ultrahigh vacuum cryogenic conditions similar to those in cold prestellar clouds. The composition of ices was chosen to reflect current astrochemical notions. The following interstellar ice analogues were obtained: H$_2$O : CH$_4$ = 10 : 1, CO$_2$ : CH$_4$ = 5 : 1, CH$_3$OH : CH$_4$ = 2 : 1, NH$_3$ : CH$_4$ = 1 : 1, that are new to the literature and infrared spectra ice analogues databases. We report the significance of deposition temperature for the internal structure of ices, which gets revealed on infrared spectra during the warm up for ices deposited at 6.7 K and 10 K. We link the observed differences to solid methane being in amorphous phase ($T < 9.3$ K) and low-temperature crystalline (9.3 K $ < T < 20$ K) phases. We also note that the direct comparison between laboratory and observational spectra is possible since the deformation mode line shape doesn't depend on the grain size or shape near 7.7 $\mu$m, only on the temperature and molecular environment. Solid methane is a fairly abundant molecule in prestellar objects. With the James Webb Space Telescope (JWST) launch the quality of spectra has risen significantly and we hope that this work will be an asset to assigning the methane component in star-forming regions.
Keywords:
ISM: molecules, clouds, lines and bands; infrared: ISM; methods: laboratory: solid state; astrochemistry
ISM: molecules, clouds, lines and bands; infrared: ISM; methods: laboratory: solid state; astrochemistry
1. Boogert A.C.A., Gerakines P.A., Whittet D.C.B., 2015, Annual Review of Astronomy and Astrophysics, 53, p. 541
2. Gerakines P.A. and Hudson R.L., 2015, Astrophysical Journal Letters, 805, 2, id. L20
3. McClure M.K., Rocha W.R.M., Pontoppidan K.M., et al., 2023, Nature Astronomy, 7, p. 431
