Signs of a faint disc population at polluted white dwarfs
Signs of a faint disc population at polluted white dwarfs
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DOI：
10.1093/mnras/stu1565
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发表时间：
2014-08
影响因子：
4.8
通讯作者：
C. Bergfors;J. Farihi;P. Dufour;M. Rocchetto
中科院分区：
文献类型：
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作者：
C. Bergfors;J. Farihi;P. Dufour;M. Rocchetto
对白矮星周围大气金属和尘埃盘的观测为了解中等质量恒星周围的类地行星系统的命运提供了重要线索。我们给出了15颗金属污染的白矮星的斯皮策红外阵列相机观测，以研究由行星体破裂产生的星际尘埃的存在和物理性质。我们发现微妙的红外线超额辐射与kuv 15519+1730和hs2132+0941附近的暖尘埃一致，而DZ白矮星G24558附近的超额辐射较弱，如果是真的，这使它成为已知的最冷的白矮星，表现出3.6um的超额辐射，也是第一颗拥有明亮圆盘的DZ恒星。总而言之，我们的数据对图片进行了综合评级，其中(1)金属丰富的白矮星上的圆盘很常见，大多数逃脱了红外探测(可能是窄环)，(2)这些圆盘寿命很长，寿命约为106年或更长，(3)明亮的红外可探测圆盘的频率随着年龄的增长而下降，时间尺度约为500Myr，这表明在相同的时间尺度上，大型行星小扰动的下降。
Observations of atmospheric metals and dust discs around white dwarfs provide important clues to the fate of terrestrial planetary systems around in termediate mass stars. We present Spitzer Infrared Array Camera observations of 15 metal polluted white dwarfs to investigate the occurrence and physical properties of circumstellar dust created by the disruption of planetary bodies. We find subtle infrared excess emission co nsistent with warm dust around KUV 15519+1730 and HS 2132+0941, and weaker excess around the DZ white dwarf G24558, which, if real, makes it the coolest white dwarf known to exhibit a 3.6µm excess and the first DZ star with a bright disc. All together our data corrobo rate a picture where (1) discs at metal-enriched white dwarfs are commonplace and most escape detection in the infrared (possibly as narrow rings), (2) the discs are long lived, hav ing lifetimes on the order of 10 6 yr or longer, and (3) the frequency of bright, infrared detecta ble discs decreases with age, on a timescale of roughly 500 Myr, suggesting large planetesimal disruptions decline on this same timescale.