scholarly journals Time-series and Phase-curve Photometry of the Episodically Active Asteroid (6478) Gault in a Quiescent State Using APO, GROWTH, P200, and ZTF

2021 ◽  
Author(s):  
Josiah Purdum ◽  
Zhong-Yi Lin ◽  
Bryce Bolin ◽  
Kritti Sharma ◽  
Philip Choi ◽  
...  
Keyword(s):  
Time Series ◽  
North America ◽  
Physical Properties ◽  
Rotation Period ◽  
Absolute Magnitude ◽  
Phase Curve ◽  
Quiescent State ◽  
Surface Mass ◽  
Critical Rotation ◽  
Near Earth Asteroids

<p>We observed the episodically active asteroid (6478) Gault in 2020 with multiple telescopes in Asia and North America and found that it is no longer active after its recent outbursts at the end of 2018 and the start of 2019. The inactivity during this apparition allowed us to measure the absolute magnitude of Gault of Hr = 14.63 ± 0.02, Gr = 0.21 ± 0.02 from our secular phase-curve observations. In addition, we were able to constrain Gault’s rotation period using timeseries photometric lightcurves taken over 17 hr on multiple days in 2020 August, September, and October. The photometric lightcurves have a repeating <0.05 mag feature suggesting that (6478) Gault has a rotation period of ∼2.5 hr and may have a semispherical or top-like shape, much like the near-Earth asteroids Ryugu and Bennu. The rotation period of ∼2.5 hr is near the expected critical rotation period for an asteroid with the physical properties of (6478) Gault, suggesting that its activity observed over multiple epochs is due to surface mass shedding from its fast rotation spin-up by the Yarkovsky–O’Keefe–Radzievskii–Paddack effect.</p>

scholarly journals Time-series and Phase-curve Photometry of the Episodically Active Asteroid (6478) Gault in a Quiescent State Using APO, GROWTH, P200, and ZTF

2021 ◽  
Vol 911 (2) ◽  
pp. L35
Author(s):  
Josiah N. Purdum ◽  
Zhong-Yi Lin ◽  
Bryce T. Bolin ◽  
Kritti Sharma ◽  
Philip I. Choi ◽  
...  
Keyword(s):  
Time Series ◽  
Phase Curve ◽  
Quiescent State

ALUCHROM YHf

Alloy Digest ◽  
2004 ◽  
Vol 53 (1) ◽  
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
High Temperature ◽  
North America ◽  
Physical Properties ◽  
Tensile Properties ◽  
Heat Treating ◽  
Pressure Vessels ◽  
Temperature Performance ◽  
Oxidation Resistant

Abstract Aluchrom YHf is an oxidation resistant ferritic stainless steel alloyed with aluminum. The alloy is approved in North America and Europe for pressure vessels to 899 deg C (1650 deg F). This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-899. Producer or source: ThyssenKrupp VDM GmbH.

UDDEHOLM RAMAX LH

Alloy Digest ◽  
2010 ◽  
Vol 59 (2) ◽  
Keyword(s):  
Corrosion Resistance ◽  
North America ◽  
Physical Properties ◽  
Tensile Properties ◽  
Heat Treating ◽  
Good Corrosion Resistance ◽  
Base Steel ◽  
Machining Properties

Abstract Ramax LH is a chromium alloyed mold base steel that exhibits excellent machining properties. It displays good corrosion resistance and is delivered in the prehardened condition. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on corrosion resistance as well as heat treating, machining, and joining. Filing Code: SS-1054. Producer or source: Böhler-Uddeholm North America.

OVAX 800

Alloy Digest ◽  
2009 ◽  
Vol 58 (4) ◽  
Keyword(s):  
Shear Strength ◽  
North America ◽  
Physical Properties ◽  
Tensile Properties

Abstract OvaX 800 is a through-hardening steel for bearing and transmission applications. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear strength. It also includes information on casting, forming, and machining. Filing Code: SA-596. Producer or source: Ovako North America Inc.

OVAKO 803 J/EN 100CR6

Alloy Digest ◽  
2008 ◽  
Vol 57 (7) ◽  
Keyword(s):  
Fatigue Strength ◽  
North America ◽  
Physical Properties ◽  
Tensile Properties ◽  
Heat Treating ◽  
Cold Forming ◽  
Bearing Steels

Abstract Ovako 100Cr6 comprises a group of through-hardening bearing steels with modification to improve machining, cold forming, and cleanliness for better fatigue strength. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on casting, forming, and heat treating. Filing Code: SA-582. Producer or source: Ovako North America Inc.

BÖHLER K700

Alloy Digest ◽  
2015 ◽  
Vol 64 (11) ◽  
Keyword(s):  
Fracture Toughness ◽  
Wear Resistance ◽  
North America ◽  
Physical Properties ◽  
Precipitation Hardening ◽  
Base Alloy ◽  
Heat Treating ◽  
Nickel Base Alloy ◽  
Typical Application ◽  
Nickel Base

Abstract Böhler (or Boehler) K700 is a nickel base alloy for high temperatures that is precipitation hardening. Aerospace engines are a typical application. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on wear resistance as well as forming, heat treating, machining, and joining. Filing Code: TS-731. Producer or source: Böhler-Uddeholm North America.

BÖHLER S200

Alloy Digest ◽  
2017 ◽  
Vol 66 (9) ◽  
Keyword(s):  
North America ◽  
Physical Properties ◽  
High Speed ◽  
High Speed Steel ◽  
Heat Treating ◽  
Red Hardness

Abstract Böhler (or Boehler) S200 is a high-speed steel with good toughness and red hardness. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on surface qualities as well as forming, heat treating, and machining. Filing Code: TS-741. Producer or source: Böhler-Uddeholm North America.

BÖHLER W405 ISOBLOC

Alloy Digest ◽  
2013 ◽  
Vol 62 (10) ◽  
Keyword(s):  
Thermal Conductivity ◽  
North America ◽  
Physical Properties ◽  
Heat Treating ◽  
Damage Mechanisms ◽  
Hot Work Steel

Abstract Böhler (or Boehler) W405 is a hot work steel with a great combination of hardness, strength, toughness, ductility, and thermal conductivity to resist typical damage mechanisms in applications. This datasheet provides information on composition, physical properties, and elasticity. It also includes information on forming and heat treating. Filing Code: TS-722. Producer or source: Böhler-Uddeholm North America.

BÖHLER K490 MICROCLEAN

Alloy Digest ◽  
2016 ◽  
Vol 65 (2) ◽  
Keyword(s):  
Fracture Toughness ◽  
Wear Resistance ◽  
North America ◽  
Physical Properties ◽  
Tool Steel ◽  
Cold Work ◽  
Heat Treating ◽  
Powder Metal ◽  
Cold Work Tool Steel

Abstract Böhler (or Boehler) K490 Microclean is an improved and more efficient cold work tool steel compared with other commonly used PM steels such as M4 or PM23. Toughness is more than doubled with a similar wear resistance. This datasheet provides information on composition and physical properties as well as fracture toughness. It also includes information on forming, heat treating, and powder metal forms. Filing Code: TS-734. Producer or source: Böhler-Uddeholm North America. See also Alloy Digest TS-740, April 2017.

scholarly journals The duration of the active phase on surge-type glaciers: contrasts between Svalbard and other regions

1991 ◽  
Vol 37 (127) ◽  
pp. 388-400 ◽  
Author(s):  
Julian A. Dowdeswell ◽  
Gordon S. Hamilton ◽  
Jon Ove Hagen
Keyword(s):  
Time Series ◽  
North America ◽  
Active Phase ◽  
Aerial Photographs ◽  
Polar Ice ◽  
Phase Duration ◽  
Field Surveys ◽  
The World ◽  
Glacier Surges ◽  
Fast Motion

AbstractMany glaciers in Svalbard and in other glacierized areas of the world are known to surge. However, the time series of observations required to assess the duration of fast motion is very restricted. Data on active-phase duration in Svalbard come from aerial photographs, satellite imagery, field surveys and airborne reconnaissance. Evidence on surge duration is available for eight Svalbard ice masses varying from 3 to 1250 km2. Worldwide, active-phase duration is recorded for less than 50 glaciers. Few observations are available on high polar ice masses. The duration of the active phase is significantly longer for Svalbard glaciers than for surge-type glaciers in other areas from which data are available. In Svalbard, the active phase may last from 3 to 10 years. By contrast, a surge duration of 1–2 years is more typical of ice masses in northwest North America, Iceland and the Pamirs. Ice velocities during the protracted active phase on Svalbard glaciers are considerably lower than those for many surge-type glaciers in these other regions. Mass is transferred down-glacier more slowly but over a considerably longer period. Svalbard surge-type glaciers do not exhibit the very abrupt termination of the active phase, over periods of a few days, observed for several Alaskan glaciers. The duration of the active phase in Svalbard is not dependent on parameters related to glacier size. The quiescent phase is also relatively long (50–500 years) for Svalbard ice masses. Detailed field monitoring of changing basal conditions through the surge cycle is required from surge-type glaciers in Svalbard in order to explain the significantly longer length of the active phase for glaciers in the archipelago, which may also typify other high polar ice masses. The finding that surge behaviour, in the form of active-phase duration, shows systematic differences between different regions and their environments has important implications for understanding the processes responsible for glacier surges.

Sign in / Sign up

Export Citation Format

Share Document