Outburst and Splitting of Interstellar Comet 2I/Borisov

We present Hubble Space Telescope observations of a photometric outburst and splitting event in interstellar comet 2I/Borisov. &#160; The outburst, first reported with the comet outbound at 2.8 AU (Drahus et al.~2020), was caused by the expulsion of solid particles having a combined cross-section about 100 sq. km and a mass in 0.1 mm sized particles&#160; 2e7 kg. &#160;The latter corresponds to 1e-4 of the mass of the nucleus, taken as a sphere of radius 500 m. &#160;A transient&#160; double nucleus was observed on UT 2020 March 30 (about three weeks after the outburst), having a cross-section 0.6 sq. km and corresponding dust mass 1e5 kg. &#160;The secondary was absent in images taken on and before March 28, and in images taken on and after April 03. &#160;The unexpectedly delayed appearance and rapid disappearance of the secondary are consistent with an origin through rotational bursting of one or more large (meter-sized) boulders under the action of outgassing torques, following their ejection from the main nucleus. &#160;Overall, our observations &#160;reveal that the outburst and splitting of the nucleus are minor events involving a negligible fraction of the total mass: 2I/Borisov will survive its passage through the planetary region largely unscathed. Journal: The Astrophysical Journal Letters, Volume 896, Issue 2, id.L39 &#160;

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[ITAL]Hubble Space Telescope[/ITAL] Observations of the Double Nucleus of NGC 4486B

The Astrophysical Journal ◽

10.1086/310344 ◽

1996 ◽

Vol 471 (2) ◽

pp. L79-L82 ◽

Cited By ~ 57

Author(s):

Tod R. Lauer ◽

Scott Tremaine ◽

Edward A. Ajhar ◽

Ralf Bender ◽

Alan Dressler ◽

...

Keyword(s):

Hubble Space Telescope ◽

Space Telescope ◽

Double Nucleus

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Torsional Buckling of the Hubble Space Telescope Solar Arrays

International Journal of Space Structures ◽

10.1177/026635119801300202 ◽

1998 ◽

Vol 13 (2) ◽

pp. 65-74

Author(s):

Earl A. Thornton ◽

David L Eby ◽

Peter W. Chung

Keyword(s):

Cross Section ◽

Hubble Space Telescope ◽

Solar Array ◽

Torsional Buckling ◽

Buckling Loads ◽

Space Telescope ◽

Linear Elastic ◽

Solar Arrays ◽

Buckling Behavior ◽

Open Cross Section

The buckling behavior of a flexible rolled-up solar array used on the Hubble Space Telescope (HST) is investigated analytically and experimentally. Analytically, the solar array is modeled assuming the booms are linear, elastic beams of open cross-section, and the solar blanket is represented as an inextensible membrane. The analyses determine critical buckling loads for flexure and torsion. The behavior of the solar array is also investigated by experiments conducted using a model solar array with (1) closed cross-section booms, and (2) tubular booms like those used on the HST. The analyses and experiments show that the Hubble's solar arrays were deployed with a preload that caused them to buckle in torsion. Based on the study, an hypothesis is suggested for the failure of the solar array's booms that was discovered by the astronauts in 1993.

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Initial Characterization of Active Transitioning Centaur, P/2019 LD2 (ATLAS)

10.5194/epsc2021-145 ◽

2021 ◽

Author(s):

Bryce Bolin ◽

Yanga Fernandez ◽

Carey Lisse ◽

Timothy Holt

Keyword(s):

Cross Section ◽

Hubble Space Telescope ◽

Gas Production ◽

Wide Field ◽

Imaging Spectrometer ◽

Space Telescope ◽

Resolution Imaging ◽

Array Camera

We present visible and mid-infrared imagery and photometry of temporary Jovian co-orbital comet P/2019 LD2 taken with Hubble Space Telescope/Wide Field Camera 3 (HST/WFC3), Spitzer Space Telescope/Infrared Array Camera (Spitzer/IRAC), and the GROWTH telescope network, visible spectroscopy from Keck/Low-Resolution Imaging Spectrometer (LRIS), and archival Zwicky Transient Facility observations taken between 2019 April and 2020 August. Our observations indicate that the nucleus of LD2 has a radius between 0.2 and 1.8 km assuming a 0.08 albedo and a coma dominated by &#8764;100 &#956;m-scale dust ejected at &#8764;1m s&#8722;1 speeds with a &#8764;1'' jet pointing in the southwest direction. LD2 experienced a total dust mass loss of &#8764;108 kg at a loss rate of &#8764;6 kg s&#8722;1 with Af&#961;/ cross-section varying between &#8764;85 cm/125 km2 and &#8764;200 cm/310 km2 from 2019 April 9 to 2019 November 8. If the increase in Af&#961;/cross section remained constant, it implies LD2&#700;s activity began &#8764;2018 November when within 4.8 au of the Sun, implying the onset of H2O sublimation. We measure CO/CO2 gas production of <1027 mol s&#8722;1/<1026 mol s&#8722;1 from our 4.5 &#956;m Spitzer observations; g&#8211;r = 0.59 &#177; 0.03, r&#8211;i = 0.18 &#177; 0.05, and i&#8211; z = 0.01 &#177; 0.07 from GROWTH observations; and H2O gas production of <80 kg s&#8722;1 scaling from our estimated C2 production of QC2 < 7.5 x 1024 mol s&#8722;1 from Keck/LRIS spectroscopy. We determine that the long-term orbit of LD2 is similar to Jupiter-family comets having close encounters with Jupiter within &#8764;0.5 Hill radius in the last &#8764;3 y and within 0.8 Hill radius in &#8764;9 y. Additionally, 78.8% of our orbital clones are ejected from the solar system within 106 yr, having a dynamical half-life of 3.4 &#215; 105 yr.

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