Введение
Звезда класса светимости VI по системе спектральной классификации Йеркеса.
A subdwarf, sometimes denoted by "sd", is a star with luminosity class VI under the Yerkes spectral classification system. They are defined as stars with luminosity 1.5 to 2 magnitudes lower than that of main sequence stars of the same spectral type. On a Hertzsprung–Russell diagram subdwarfs appear to lie below the main sequence. The term "subdwarf" was coined by Gerard Kuiper in 1939, to refer to a series of stars with anomalous spectra that were previously labeled as "intermediate white dwarfs". This lower opacity also allows them to emit a higher percentage of ultraviolet light for the same spectral type relative to a Population I star, a feature known as the ultraviolet excess. Usually members of the Milky Way's halo, they frequently have high space velocities relative to the Sun. Cool subdwarfs of spectral type L and T exist, for example ULAS J131610.28+075553.0 with spectral type sdT6.5. cool subdwarf Examples: Kapteyn's Star (sdM1), GJ 1062 (sdM2.5)
extreme subdwarf Example: APMPM J0559 2903 (esdM7)
ultrasubdwarf Example: LSPM J0822+1700 (usdM7.5) 2MASS J0532+8246 was discovered in 2003 as the first L type subdwarf, which was later re classified as an extreme subdwarf. 2MASSI J0937347+293142 is the first object that was discovered in 2002 as a T type subdwarf candidate The first two extreme subdwarfs of type T were discovered in 2020 by scientists and volunteers of the Backyard Worlds project. The first extreme subdwarfs of type T are WISEA 0414−5854 and WISEA 1810−1010. The color of T types as a single classification criterion can be misleading. The closest directly imaged exoplanet, COCONUTS 2b, was first classified as a subdwarf of type T due to its color, while not showing a high tangential velocity. Only in 2021 it was identified as an exoplanet. The first Y type subdwarf candidate was discovered in 2021, the brown dwarf WISE 1534–1043, which shows a moderate red Spitzer Space Telescope color (ch1 ch2 = 0.925±0.039 mag). The very red color between J and ch2 (J ch2 > 8.03 mag) and the absolute brightness would suggest a much redder ch1 ch2 color of about 2.4 to 3 mag. Due to the agreement with new subdwarf models, together with the high tangential velocity of 200 km/s, Kirkpatrick, Marocco et al. (2021) argue that the most likely explanation is a cold very low metal brown dwarf, maybe the first subdwarf of type Y.
Субкарлик, иногда обозначаемый как "sd", – это звезда класса светимости VI по системе спектральной классификации Йеркеса. Они определяются как звезды с яркостью на 1,5–2 величины меньше, чем у звезд главной последовательности того же спектрального типа. На диаграмме Герцшпрунга — Рассела субкарлики располагаются ниже главной последовательности. Термин "субкарлик" был введен Джераром Койпером в 1939 году для обозначения ряда звезд с аномальными спектрами, которые ранее классифицировались как "промежуточные белые карлики". Эта более низкая непрозрачность также позволяет им излучать больший процент ультрафиолетового света для одного и того же спектрального типа по сравнению со звездой популяции I, что известно как ультрафиолетовый избыток. Обычно они являются членами гало Млечного Пути и часто имеют высокие пространственные скорости относительно Солнца. Существуют холодные субкарлики спектральных типов L и T, например ULAS J131610.28+075553.0 со спектральным типом sdT6.5. Примеры: Звезда Каптейна (sdM1), GJ 1062 (sdM2.5).
A subdwarf, sometimes denoted by "sd", is a star with luminosity class VI under the Yerkes spectral classification system. They are defined as stars with luminosity 1.5 to 2 magnitudes lower than that of main sequence stars of the same spectral type. On a Hertzsprung–Russell diagram subdwarfs appear to lie below the main sequence. The term "subdwarf" was coined by Gerard Kuiper in 1939, to refer to a series of stars with anomalous spectra that were previously labeled as "intermediate white dwarfs". This lower opacity also allows them to emit a higher percentage of ultraviolet light for the same spectral type relative to a Population I star, a feature known as the ultraviolet excess. Usually members of the Milky Way's halo, they frequently have high space velocities relative to the Sun. Cool subdwarfs of spectral type L and T exist, for example ULAS J131610.28+075553.0 with spectral type sdT6.5. cool subdwarf Examples: Kapteyn's Star (sdM1), GJ 1062 (sdM2.5)
extreme subdwarf Example: APMPM J0559 2903 (esdM7)
ultrasubdwarf Example: LSPM J0822+1700 (usdM7.5) 2MASS J0532+8246 was discovered in 2003 as the first L type subdwarf, which was later re classified as an extreme subdwarf. 2MASSI J0937347+293142 is the first object that was discovered in 2002 as a T type subdwarf candidate The first two extreme subdwarfs of type T were discovered in 2020 by scientists and volunteers of the Backyard Worlds project. The first extreme subdwarfs of type T are WISEA 0414−5854 and WISEA 1810−1010. The color of T types as a single classification criterion can be misleading. The closest directly imaged exoplanet, COCONUTS 2b, was first classified as a subdwarf of type T due to its color, while not showing a high tangential velocity. Only in 2021 it was identified as an exoplanet. The first Y type subdwarf candidate was discovered in 2021, the brown dwarf WISE 1534–1043, which shows a moderate red Spitzer Space Telescope color (ch1 ch2 = 0.925±0.039 mag). The very red color between J and ch2 (J ch2 > 8.03 mag) and the absolute brightness would suggest a much redder ch1 ch2 color of about 2.4 to 3 mag. Due to the agreement with new subdwarf models, together with the high tangential velocity of 200 km/s, Kirkpatrick, Marocco et al. (2021) argue that the most likely explanation is a cold very low metal brown dwarf, maybe the first subdwarf of type Y.
Экстремальный субкарлик. Пример: APMPM J0559 2903 (esdM7).
A subdwarf, sometimes denoted by "sd", is a star with luminosity class VI under the Yerkes spectral classification system. They are defined as stars with luminosity 1.5 to 2 magnitudes lower than that of main sequence stars of the same spectral type. On a Hertzsprung–Russell diagram subdwarfs appear to lie below the main sequence. The term "subdwarf" was coined by Gerard Kuiper in 1939, to refer to a series of stars with anomalous spectra that were previously labeled as "intermediate white dwarfs". This lower opacity also allows them to emit a higher percentage of ultraviolet light for the same spectral type relative to a Population I star, a feature known as the ultraviolet excess. Usually members of the Milky Way's halo, they frequently have high space velocities relative to the Sun. Cool subdwarfs of spectral type L and T exist, for example ULAS J131610.28+075553.0 with spectral type sdT6.5. cool subdwarf Examples: Kapteyn's Star (sdM1), GJ 1062 (sdM2.5)
extreme subdwarf Example: APMPM J0559 2903 (esdM7)
ultrasubdwarf Example: LSPM J0822+1700 (usdM7.5) 2MASS J0532+8246 was discovered in 2003 as the first L type subdwarf, which was later re classified as an extreme subdwarf. 2MASSI J0937347+293142 is the first object that was discovered in 2002 as a T type subdwarf candidate The first two extreme subdwarfs of type T were discovered in 2020 by scientists and volunteers of the Backyard Worlds project. The first extreme subdwarfs of type T are WISEA 0414−5854 and WISEA 1810−1010. The color of T types as a single classification criterion can be misleading. The closest directly imaged exoplanet, COCONUTS 2b, was first classified as a subdwarf of type T due to its color, while not showing a high tangential velocity. Only in 2021 it was identified as an exoplanet. The first Y type subdwarf candidate was discovered in 2021, the brown dwarf WISE 1534–1043, which shows a moderate red Spitzer Space Telescope color (ch1 ch2 = 0.925±0.039 mag). The very red color between J and ch2 (J ch2 > 8.03 mag) and the absolute brightness would suggest a much redder ch1 ch2 color of about 2.4 to 3 mag. Due to the agreement with new subdwarf models, together with the high tangential velocity of 200 km/s, Kirkpatrick, Marocco et al. (2021) argue that the most likely explanation is a cold very low metal brown dwarf, maybe the first subdwarf of type Y.
Ультрасубкарлик. Пример: LSPM J0822+1700 (usdM7.5). 2MASS J0532+8246 был обнаружен в 2003 году как первый субкарлик типа L, который впоследствии был переклассифицирован как экстремальный субкарлик. 2MASSI J0937347+293142 – первый объект, обнаруженный в 2002 году как кандидат в субкарлики типа T. Первые два экстремальных субкарлика типа T были обнаружены в 2020 году учеными и волонтерами проекта Backyard Worlds. Первыми экстремальными субкарликами типа T являются WISEA 0414−5854 и WISEA 1810−1010. Цвет типов T как единственный критерий классификации может быть обманчивым. Ближайшая непосредственно заснятая экзопланета COCONUTS 2b первоначально была классифицирована как субкарлик типа T из-за своего цвета, хотя и не демонстрировала высокой тангенциальной скорости. Лишь в 2021 году она была идентифицирована как экзопланета. Первый кандидат в субкарлики типа Y был обнаружен в 2021 году – коричневый карлик WISE 1534–1043, который показывает умеренно красный цвет, полученный с помощью космического телескопа Spitzer (ch1 ch2 = 0,925±0,039 м). Очень красный цвет между J и ch2 (J ch2 > 8,03 м) и абсолютная яркость указывают на гораздо более красный цвет ch1 ch2 примерно от 2,4 до 3 м. В связи с соответствием новым моделям субкарликов, а также высокой тангенциальной скоростью 200 км/с, Киркпатрик, Марокко и др. (2021) утверждают, что наиболее вероятным объяснением является холодный коричневый карлик с очень низким содержанием металлов, возможно, первый субкарлик типа Y.
A subdwarf, sometimes denoted by "sd", is a star with luminosity class VI under the Yerkes spectral classification system. They are defined as stars with luminosity 1.5 to 2 magnitudes lower than that of main sequence stars of the same spectral type. On a Hertzsprung–Russell diagram subdwarfs appear to lie below the main sequence. The term "subdwarf" was coined by Gerard Kuiper in 1939, to refer to a series of stars with anomalous spectra that were previously labeled as "intermediate white dwarfs". This lower opacity also allows them to emit a higher percentage of ultraviolet light for the same spectral type relative to a Population I star, a feature known as the ultraviolet excess. Usually members of the Milky Way's halo, they frequently have high space velocities relative to the Sun. Cool subdwarfs of spectral type L and T exist, for example ULAS J131610.28+075553.0 with spectral type sdT6.5. cool subdwarf Examples: Kapteyn's Star (sdM1), GJ 1062 (sdM2.5)
extreme subdwarf Example: APMPM J0559 2903 (esdM7)
ultrasubdwarf Example: LSPM J0822+1700 (usdM7.5) 2MASS J0532+8246 was discovered in 2003 as the first L type subdwarf, which was later re classified as an extreme subdwarf. 2MASSI J0937347+293142 is the first object that was discovered in 2002 as a T type subdwarf candidate The first two extreme subdwarfs of type T were discovered in 2020 by scientists and volunteers of the Backyard Worlds project. The first extreme subdwarfs of type T are WISEA 0414−5854 and WISEA 1810−1010. The color of T types as a single classification criterion can be misleading. The closest directly imaged exoplanet, COCONUTS 2b, was first classified as a subdwarf of type T due to its color, while not showing a high tangential velocity. Only in 2021 it was identified as an exoplanet. The first Y type subdwarf candidate was discovered in 2021, the brown dwarf WISE 1534–1043, which shows a moderate red Spitzer Space Telescope color (ch1 ch2 = 0.925±0.039 mag). The very red color between J and ch2 (J ch2 > 8.03 mag) and the absolute brightness would suggest a much redder ch1 ch2 color of about 2.4 to 3 mag. Due to the agreement with new subdwarf models, together with the high tangential velocity of 200 km/s, Kirkpatrick, Marocco et al. (2021) argue that the most likely explanation is a cold very low metal brown dwarf, maybe the first subdwarf of type Y.
Субкарлики из тяжелых металлов
Подкарлики, богатые тяжелыми металлами, — это тип горячих подкарликов, характеризующийся высокой концентрацией тяжелых металлов. Среди обнаруженных металлов — германий, стронций, иттрий, цирконий и свинец. К известным подкарликам, богатым тяжелыми металлами, относятся HE 2359-2844, LS IV 14 116 и HE 1256-2738.