Selasa, 01 Desember 2009

Kura-kura


Kura-kura dan penyu adalah hewan bersisik berkaki empat yang termasuk golongan reptil. Bangsa hewan yang disebut (ordo) Testudinata (atau Chelonians) ini khas dan mudah dikenali dengan adanya ‘rumah’ atau batok (bony shell) yang keras dan kaku.

Batok kura-kura ini terdiri dari dua bagian. Bagian atas yang menutupi punggung disebut karapas (carapace) dan bagian bawah (ventral, perut) disebut plastron. Kemudian setiap bagiannya ini terdiri dari dua lapis. Lapis luar umumnya berupa sisik-sisik besar dan keras, dan tersusun seperti genting; sementara lapis bagian dalam berupa lempeng-lempeng tulang yang tersusun rapat seperti tempurung. Perkecualian terdapat pada kelompok labi-labi (Trionychoidea) dan jenis penyu belimbing, yang lapis luarnya tiada bersisik dan digantikan lapisan kulit di bagian luar tempurung tulangnya.

Dalam bahasa Indonesia, kita mengenal tiga kelompok hewan yang termasuk bangsa ini, yalah penyu (bahasa Inggris: sea turtles), labi-labi atau bulus (freshwater turtles), dan kura-kura (tortoises). Dalam bahasa Inggris, dibedakan lagi antara kura-kura darat (land tortoises) dan kura-kura air tawar (freshwater tortoises atau terrapins).

Armored Core (series)

Description

Armored Core games are Mecha Simulation / third-person shooters, in which the player pilots a large mecha called an Armored Core, or AC for short. The name Core comes from the unlimited endurance Power-Generators Technology used recently among the different nations, in conjunction with a practically unlimited variety of Weapons, and Vehicle Propulsion-systems, manufactured by several different companies, Some of them the most opposed companies of all time, hailing from many different backgrounds of the Warfare Machinery Industry ( Robotics, Metallurgy, Ballistic, etc ).

The player builds their AC from parts that can be bought from a shop, found in missions, or by fulfilling certain requirements. Money is earned by performing missions as a mercenary, giving the player some choice in which missions to engage in.

Typically, in each game, up until Armored Core 4, the player is a 'Raven', a member of a mercenary organization, and is hired by corporations to do various missions, then after the mission, they are charged for repairs and ammunition, after which one can continue on with missions or customize their AC.
[edit] Muscle Tracer (MT)

The Muscle Tracer (MT) is the precursor to the Armored Core. MTs are the most frequent enemies in the series, aside from other ACs. They come in various varieties, such as mobile gun turrets, powered suits, tank-like quadrupeds, and much more. Some MTs even resemble Armored Cores.

Certain variations of MTs are transformable, such as the Scimitar MT from Armored Core: Project Phantasma, which has the capability to transform from a bipedal unit with a large top to a very fast and agile hit-and-run fighter. It appears in Armored Core: Project Phantasma and Armored Core: Nexus (REVOLUTION disc). The Scimitar MT possesses moderate weapons capabilities, and a squad or two of the Scimitar can easily destroy an unwary Armored Core.

They are always non-player characters, though in some games MTs accompany the player's AC as friendly support. MTs are mainly used by the corporations to resolve disputes without dealing with the Ravens or their "dispute resolution" organizations (Raven's Nest, Nerves Concord, Global Cortex, Raven's Ark), although MTs have been used by artificial intelligences as well.
[edit] Nexts and Normals

Armored Core 4 and Armored Core for Answer re-establishes AC's and MT's. The AC's are considered to be advanced in comparison to their predecessors and are called Next's. AC's in this universe utilize a Particle shield called "Primal Armor" that activates when an AC is dealt with weapon's fire. MT's still exist but are limited to being bipedal tanks. Humanoid MT's are referred to as Normals and are more combat efficient than regular MT's.
[edit] Cored MT Unit (Armored Core)

The full name for a Muscle Tracer that is not mass-produced as a single unit in bulk, Cored MT Units are much more powerful than their counterparts and are built differently. Instead of a single set of parts being used, and different models of the MT being built, an Armored Core is built from several different interchangeable parts, to allow maximum customization by their pilots. Some Armored Cores have also been custom made, and the corporations have not reproduced their parts.
[edit] Anatomy of an AC

The structure of an AC is standardized and modular, consisting of a number of parts which are fitted together in the AC Garage. Radiators, inside parts, extension parts, and hovering legs are found only in games subsequent to Armored Core 2.
[edit] Required Parts

An AC must have all of these parts in order to function.
[edit] Head

Contains visual sensors. May also contain radar and computing equipment. Some heads are better armored than others, but at the cost of lacking extra sensor equipment. The radar and sensor equipment is broken down into several categories including Bio-Sensor, Noise Canceler, Night Vision, Missile Sensor and Auto-Map.

In Armored Core: Nexus onward, the stability of the head is now factored in when determining the stability of an AC, whereas traditionally it had only been affected by the legs and optional parts. Light ACs and others with weak stability generally tend to stick to the few heads with high stability, while heavier ACs can use heavier heads with weaker stability stats.

* Auto-Map: allows a player to check the map screen of the game and see all traversed areas detected within a limited radius at any time. Heads without the Auto-Map function can only view the map of the area immediately around them.
* Bio-Sensor: allows an AC to detect and target biological organisms, which appear in many of the games.
* Missile Sensor: detects incoming missiles on the radar screen so that a player has the chance to dodge them before they hit. If a head has a radar but no Missile Sensor, the ability can be supplemented by an Optional Part providing this ability or a radar unit equipped with the sensor.
* Noise Canceler (Armored Core - Silent Line: Armored Core): appeared in previous games and was a prelude to Nexus 's 'vs ECM'. It helps an AC recover from electronic interference.
* Night Vision (Armored Core: Nexus - Armored Core Last Raven): Night Vision initiates automatically and lights up an area that would otherwise be too dark to see anything. It is akin to modern night vision goggles and cameras. Night Vision was removed in Armored Core 4.
* Vs. ECM (Armored Core: Nexus onward): reflects the ability of the AC to counter high levels of electronic interference. These may be the result of ECM pods used by an arena opponent or of mission-specific environmental hazards. Back radars, FCS systems, and optional parts can boost this level higher.

[edit] Core

The 'torso' of the mech. It is the 'armored core' from which the mech and the game series take their name. The human pilot sits inside the core.

Cores come in different weights to suit different styles of robot; the lighter ones are less well protected but more suitable for more mobile ACs. Similarly, there are highly defensive heavyweight cores.

Cores contain a number of slots into which Optional Parts can be placed to improve its operation. Also, some cores have built-in anti-missile systems.

As the series has progressed, new features for cores have appeared:

* Over Boost (Armored Core 2 onward): a high powered booster system that operates in combination with the external or leg based booster of an AC. When activated, it allows the player's AC to move at amazingly high speeds, but can only be used to move forward, left, right, or diagonally left or right at a forward angle, backward movement is impossible. While it offers a tremendous amount of extra speed, Over Boosting both drains energy very quickly and causes a massive increase in the core's heat level when initially used. These two factors heavily limit the amount of time an Over Boost function can be used. As of Armored Core 4, Over Boosters have become a separate, equipible part for every AC rather than a feature of certain Cores.

* Exceed Orbit (Armored Core 3 to Last Raven): Exceed Orbit (EO) cores contain one or more orbital pods that can be deployed to hover above the AC and retracted at will. They automatically target and shoot enemies. The rate of fire, power, and field of vision for EO pods varies from model to model. For EO pods with energy weapons, the ammunition supply gradually regenerates when not in use. Two important factors that limit Exceed Orbit usage are the small amounts of added heat that occur whenever an EO pod is deployed, as well as the energy drain from the pod firing. EO Cores with solid ammo do not suffer from an energy drain while firing but their ammo cannot be replenished once depleted. EO's are not featured in Armored Core 4.

* Hanger Unit (Armored Core: Nexus onward): any core with this unit can hold one spare piece of equipment for each hand. Only small weapons can be stored inside this unit, for example, a hand gun is a light weapon and grenade launchers are not. Some cores are equipped with both Over Boost and Hanger functions but there are no Exceed Orbit cores with Hangers. In Armored Core 4, all ACs are equipped with a hanger function, and it is suggested that the weapons are actually stored in the legs. This is because while the "small weapons" rule still applies to most leg types, the large, tank type legs are able to store any arm weapon.

* Primal Armor (Armored Core 4 onward): An energy shield powered by Kojima Particles (KP). Called PA for short, it reduces the damage that most weapons inflict on an AC. It is most effective at longer ranges and against shell weapons, since energy weapons have a greater ability to penetrate PA (PA piercing). However, solid weapons cause much more damage to KP (PA reduction), and can destroy PA shields (PA breaking), which leaves an AC with greatly reduced defensive capability. Beyond solid weapons breaking technique, and energy weapons piercing technique, there is a class of weapon known as Kojima weapons. There both pierce and reduce PA, and can destroy an AC in a single shot, but they need time to charge up, and draw energy from the PA of the AC wielding them, which can hurt defense. A similar ability has previously been seen on the Airborne Pulverizer in Armored Core: Last Raven. The waste emitted by Kojima Particles is a biohazard.

* Quick Boost (Armored Core 4 onward): Known as QB, this system is a function of normal boosters, that greatly increases their power and energy drain for brief moments. QB is mainly used for avoiding attacks, but it can also be used to move quickly through an area. Combined with Overboost, AC's can reach speeds approaching Mach 1.5. This ability was allowed previously only via an extension part, which also limited sudden boosts to basic directions such as forward, backward, left/right, left/right (strafe), and in whichever direction the core faces when activated.

[edit] Arms

There are two types of arms; normal arms capable of holding weapons, and weapon arms that are weapons:

* Norm, which determines how quickly the mech can swing a laser blade.

* Weapon arms sometimes possess two different firing modes, and are more powerful than ordinary weapons because they can be fired from two arms at once. However, they greatly lack in defense compared to normal arms. Weapon arms can be useful in keeping the weight of an AC down, as they are lighter than having separate arms and weapons. They also suffer from high ammo use, as both arms use the same ammo pool and fire simultaneously.

[edit] Legs

The legs support the AC on the ground and determine how it moves, and are usually the part by which an AC is classified. There are several different kinds of legs:

* Humanoid — classic bipedal humanoid-style. Comes in many different weights, speeds and strengths. Before Armored Core 4, humanoid ACs were limited in that they must kneel down to use many of the back-unit weapons (except for missiles and rockets as well as certain cannons and pod weapons). This takes time and also leaves them unable to move while firing.
o Heavy Legs are well armored, spend less energy boosting and can support heavy weights but very slow.
o Light Legs are very fast but have very low AP, expend high amounts of energy, and have low weight limits.
o Standard Legs are a balance between the other two types, with average AP, speed and weight limit. These legs are always equipped on the default AC that the player is provided at the start of each game.

* Reverse-Joint — also bipedal, these legs resemble those of a bird. Reverse-jointed ACs tend to have a lower carrying capacity; they can also jump higher. However, they have the same problem with back weapons as standard bipeds. They are not as well-armored as bipeds, have less cooling, and lower defensive stability. However, reverse-jointed legs drain less energy from the generator than other leg types, and have the best boost effectiveness while airborne.

* Four Leg — quadrupedal, similar to a spider. Four-legged were fast up until Armored Core 3 when the animation for leg movement was implemented for these parts. Prior to this change, quadrupeds moved by gliding on the ground much like hover legs. Unlike bipedal cores, (until Armored Core 4 granted the ability to all ACs) they have the ability to fire back weapons while moving, although not while airborne. However most quads, as they are known in fan circles, cannot support heavy weights, are less well-armored than bipeds, and use high amounts of energy.

* Tank Legs — slow and heavy, but very well armored and can support massive loads. Tank ACs can fire any weapon even if moving or airborne. As these kind of legs don't have any joints, they cannot jump, instead using built-in boosters to thrust upward. A disadvantage of this is that if the generator has been emptied and is recharging, the AC cannot leave the ground, unlike legged ACs which can jump.
o Tank tracks - uses a caterpillar track to move.
o Hover tank - uses hovering technology to improve speed, while sacrificing some of the armour and load carrying ability of the tank track legs.

* Hover Legs — floating platforms that do not touch the ground. Hover ACs are the fastest and most maneuverable of all ACs and can travel over water (In armored core 4 it is possible to hover above water even with a bipedal leg type.); a huge advantage on aquatic missions. They are, however, the least armored of all the leg types and can only support very light loads. They suffer the same limitations as bipeds with regards to back-unit weapons. Like Tank ACs, Hover ACs cannot jump and have built-in boosters instead, and suffer the same problem of being unable to leave the ground if the generator is recharging. They suffer from braking issues. Hover legs were introduced in Armored Core 2 up till Last Raven.

[edit] FCS

The FCS or Fire Control System is the targeting computer, and controls weapon targeting and missile lock-ons. There are several different kinds, which vary on several attributes such as lock-on speed, maximum lock-on range, maximum lock-on number, or shape and size of lock-on area, suitable for different styles of weapons.

* Missile FCS — FCS designed for use with missiles normally have a long vertical lock box, lock on very quickly with missiles and have a long detection range.
* Sniper FCS — FCS designed for sniper rifle or cannons normally have a small square lock box, lock on very slowly with missiles and have an extremely long detection range.
* Rifle FCS — FCS designed for rifle, pistol or shotgun weapons normally have a wide horizontal lock box, lock on rather slow with missiles and have a fairly short detection range.
* Standard FCS — Standard FCS don't show any particular preference when it comes to lock time, have an even square lock box and a balanced lock on distance.

[edit] Booster

Boosters enable an AC to move quickly, and to fly. They come in different strengths and efficiencies. Boosters cannot be equipped on Tank and Hover ACs, as these have built-in boosters.

In Armored Core: Nexus and beyond, players have to be cautious when equipping and using boosters because they now not only drain energy but produce heat too, which can hamper the performance of the player's AC if it overheats. The amount of heat produced from an AC's boosters is tied to the Generator's calorific value, so hotter boosters should be used with cooler running Generators with low calorific values. Armored Core 4 features a new booster system divided into Main, Back, and Side. The Main boosters are the boosters featured in all previous AC games, and control forward movement. Back boosters are the set of boosters that control how fast your AC backpedals and side boosters control how fast your AC moves from side to side. The booster power as well as other aspects of all 3 can be tuned for greater efficiency.
[edit] Generator

Supplies power to the AC. Power is an important consideration in the Armored Core games - the generator can only generate energy at a certain rate, and if the AC uses energy at a faster rate, the charge held by the generator is depleted. If the energy produced by the generator is depleted past the generator's red zone it immediately shuts off all other high-energy dependent functions and recharges, leaving the AC very vulnerable. Recharging ACs cannot use their boosters or energy weaponry until the generator has completely recharged, and in battle up to a minute without weapons or mobility can end up costing a heavy price. The time it takes to recharge varies from generator to generator; also, the generator is still supporting the AC's necessary functions while charging, and these (particularly the radiator) slow the recharge rate. The quickest way to recharge, therefore, is to stand completely still and do nothing. In Armored Core 4, Generators also gain the ability to produce Kojima Particles, or KP. AC's use KP's to power their Primal Armor defense shield, as well as KP powered weapons. As with EN output, different levels of KP output dictate the PA shields recharge rate. Generators no longer recharge in AC4. Instead, when they reach zero energy, they build up energy at the regular rate. However, this does not equate to unlimited power, since if energy is low enough, energy weapons and boosters do not function.
[edit] Radiator (Armored Core 2-Armored Core: Last Raven)

ACs can get very hot, and when overheated their combat effectiveness is reduced. Radiators attempt to release this heat, with varying efficiency. Heat is produced by taking hits from various types of weaponry, by the external environment, and in Armored Core: Nexus by the AC's boosters.

From Armored Core 2 to Silent Line: Armored Core, an overheated AC would incur damage until the temperature was lowered.

In Armored Core: Nexus the heat system was completely reworked. Now heat does not do instant damage to an AC, but when an AC becomes overheated the radiator begins sucking massive amounts of energy from the AC's generator to cool down the core. This can quickly deplete its energy supply and leave it vulnerable if the radiator is not very efficient. If the heat level cannot be brought down quick enough or goes too high too quickly, the AC will still take damage.

The Radiator parts do not appear in Armored Core 4 because the heat management system has been abandoned.
[edit] Non-Essential Parts

These parts can be left off if the player desires; the player is able to initiate missions and participate in other activities, such as the arena, without them. However, an AC will have difficulty (to the point of impossibility in relation to combat) progressing far into the game without a weapon of some kind.
[edit] Inside (Armored Core 2 - Armored Core Last Raven)

An internal compartment from which a variety of devices can be released, including bombs, mines, decoys and radar-jammers. In Armored Core 3 small rockets and napalm rockets were added to the selection. These rockets have no aiming trajectory in the HUD and needed to be fired blindly. These parts were located in the top rear of the core facing backwards in the Armored Core 2 series and in the shoulders facing forwards from Armored Core 3 onward. Inside parts are no longer present as they have been removed in Armored Core 4.
[edit] Extension (Armored Core 2-onward)

Extensions come in pairs and are mounted on the sides of the shoulders. They are miscellaneous, usually non-offensive devices, and can be anything from extra boosters to stealth devices.

* Extra boosters (with various functions)
* Anti-missile systems
* Relation missiles (extra missiles that fire simultaneously with missile launchers)
* Shoulder energy shields
* Emergency heat sinks (rapidly cools an AC)
* Emergency energy units (rapidly recharges energy)
* Enemy Radar Jamming systems

In Armored Core 3, several emergency energy units were sold - these were usually 3 uses, and would quickly refill the energy of an AC in about 5 seconds. Emergency heat sinks were also introduced that allowed a quick cooling burst to bleed off potentially damaging heat if an AC got too hot. In Armored Core 2, additional booster and relation missiles become available but in "Armored Core: Nexus" the radar jamming equipment was removed along with the radiator and ECM equipment.

In Armored Core 4, extensions have been renamed as shoulder weapons.
[edit] Back Unit

There are two points on the back where weapons or devices may be mounted. These include:

* Missile launchers
* Rocket launchers
* Guns (chain guns, slug guns, rail guns, pulse guns, etc)
* Cannons (grenade launchers, laser cannons)
* Orbit cannons (units which deploy autonomous, floating guns)
* Radars
* Extra ammunition supplies

In pre Armored Core 4 games, some weapons and devices take up both Back Unit slots. Weapons and devices that occupy two slots have returned in Armored Core for Answer, an example being a grenade launcher known as the OIGAMI.

Cannon-type weapons must be fired over the shoulder, so there is usually a delay in activating the weapon for it to unfold or align itself. Bipedal and Hovering ACs have insufficient stability to use a cannon-type weapon whilst standing or moving, so it is more common to see missile and rocket launchers on these ACs.

In earlier games AC pilots who unlocked the Human PLUS modifications or gained the black market Optional Part OP-INTENSIFY were able to deploy cannons while moving but such features have been removed from more recent games like Armored Core: Nexus, Nine Breaker and Last Raven, although in some of the AI players appear to still have access to OP-INTENSIFY.

In Armored Core 4 however, any AC with any style of legs can utilize cannon-type back weapons without having to kneel, they can be fired standing up right and while moving. Heavier AC's will be more stable when firing powerful weapons, and so are more likely to carry large cannons than lightweights. Light AC's can be heavily stunned by their own cannon fire, which hurts mobility and accuracy.
[edit] Arm Unit R

This is the right arm weapon, and for most ACs it is their primary offense. There are a large number of different weapons, including rifles, machine guns, handguns, bazookas, shotguns, grenade rifles, laser guns and various energy weapons.

In Armored Core 3, parrying blades are available - these are short-range blades used to counter a laser blade strike and deal heavy damage, however there is a significant lag time between when the trigger is pulled and when the blade activates.

The most powerful weapons in the games (with the possible exception of the range limited WA-FINGER in Project Phantasma, Master of Arena and its later incarnations in Silent Line, Nexus, Nine Breaker, Formula Front and Last Raven) are the Karasawa series, named for one of the series' producers. Armored Core has the WG-1-KARASAWA, the ZWG-KARASAWA Mk. II in Armored Core 2, and Armored Core 3 saw the MWG-KARASAWA. In Armored Core: Nexus through Armored Core: Last Raven, this weapon is called the WH04HL-KRSW, but was weakened (though this has been done since the original, which possessed nearly the best stats in the game, the extent to which it was weakened in Nexus is by far the most drastic), and reduced in ammo to 30 (Nexus) and 40 (Ninebreaker and Last Raven) from its traditional 50 shots and has been knocked off its pedestal by other more powerful weapons added in to the later games. In an attempt to make up for this fact, one is allowed to use two Karasawas from Nexus onward. The weapon was renamed HLR01-CANOPUS in Armored Core 4, and has returned to its former status.

For Armored Core 4, the Arm Weapons have been changed into a single class weapon which allows a player to equip them to either arm.
[edit] Arm Unit L

In Armored Core 1 the left arm could only be outfitted with a laser blade, which is a short-range blade of energy which can cause great damage to an opponent. From Armored Core 2 onward, one can also equip hand-held energy shields which can absorb damage from weapons and laser blades. Armored Core 3 introduces solid shields which used no energy. They could simply be activated at the beginning of a battle and would greatly reduce all frontal damage taken until they broke.

As the series has progressed, a greater variety of weapons has appeared for the left arm.Armored Core 3 introduced a few ranged weapons, such as howitzers. Silent Line: Armored Core produced a much larger selection of left arm weapons, including copies of various right arm weapons, although the reaction time to fire these is far slower when compared to weapons held by the right arm.

With the introduction of the hanger feature Armored Core: Nexus, left arm ranged weapons have become more popular, as the user can have a laser blade as a back-up weapon when ammunition is depleted (though in this case the blade may be weaker than the one that would be mounted on the AC, due to size limits on hangar parts). The equipping of another ranged weapon can result in an AC pilot never needing to engage in close range combat, thus lessening the need for laser blades. However, blades typically do more damage and have a faster rate of "fire" than most left hand weaponry, but are only effective at close range.

The most powerful blade in the series has traditionally been the "Moonlight", listed as the WL-MOONLIGHT in Armored Core, and the LS-MOONLIGHT, MLB-MOONLIGHT, and 07-MOONLIGHT in Armored Core 2, 3, and 4 respectively. Being unusually heavy for a blade, it carries the highest attack power of any blade and, by extension, nearly any weapon. It is often viewed as the traditional counterpart to the KARASAWA right arm laser rifle for most games in the series (prior to Armored Core 4, due to the merging of the arm-held weapon categories).

Just like the Right Arm, the weapons have been put into a single class weapon. (See at Arm Unit R)
[edit] Optional Parts

These are parts which can be plugged into slots in the core to enhance the AC's performance, such as increasing damage resistance to certain types of weapons, increasing the generator capacity, speeding up an FCS's lock-on time, or augmenting the attack power of energy weaponry. Different cores have different numbers of slots for optional parts, and generally more powerful optional parts cost more slots, while those only applied to certain situations are less slot-costly. Optional Parts are present through all 11 PlayStation and PlayStation 2 era Armored Core games, but have been removed from Armored Core 4-onward.
[edit] Human PLUS, Overweight, and OP-INTENSIFY

In fan circles the term "PLOW" is often used to describe ACs operating with Human PLUS or PLUS-like attributes. The term is a compound of "PLUS" and "Overweight". The term dates back to the original Armored Core, where PLUS and the Overweight features originated. PLUS abilities were "awarded" to players who repeatedly failed missions and accrued a significant loss of credits (-50,000). At this point, an FMV would play of a person (presumably the player's Raven character) undergoing surgical enhancement, and then the game resets from the beginning with the first of the PLUS abilities being unlocked. Repeating his process five more times unlocks the remaining PLUS enhancements. Every one past the fifth up until the eighth will enhance energy performance and capacity significantly. The ability to ignore the weight limit of an AC's parts is unlocked after the storyline is cleared. This ability, known as Overweight, allows the player to equip any part on an AC and still have it be playable in missions.

In Armored Core 3 and Silent Line: Armored Core a special unlockable Optional Part exists known as OP-INTENSIFY, or OP-I for short. This part, awarded upon completion of Armored Core 3’s storyline, allows for the use new features on an AC similar to the "Human PLUS" abilities of the previous games. When equipped, the part automatically takes up every Optional Part slot provided in the Core is it equipped on, and no other Optional Parts can be used while it is equipped. The main drawback of using OP-INTENSIFY comes from being unable to equip any "normal" Optional Parts and rendering the AC vulnerable to factors these parts were designed to guard against. Replaying past missions and completing specific tasks unlocks new abilities and powers up an AC equipped with OP-I. These abilities are:

* "Blade wave" projection
* Enhanced energy blade range
* Enhanced radar abilities
* All radar abilities added regardless of equipment
* Able to fire back cannons while moving on leg bases other than tanks and quadrupeds.
* Enhanced normal cooling (No effect on Forced Cooling Stats)
* Enhanced boosters
* Enhanced missile interception
* Enhanced turning abilities
* Enhanced targeting abilities

The OP-INTENSIFY and Human PLUS were removed from later AC games like Nexus, Nine Breaker, and Last Raven, yet enemies like Nexus'’s #1 Arena Raven Genobee still exhibited PLUS-like performance levels and abilities in combat.

The use of OP-INTENSIFY and Human PLUS was a source of controversy within the fan community, particularly among those who play competitively in Armored Core tournaments. The part was looked down upon by some in the community, citing that it was 'unfair' or 'cheating', though some veterans used PLUS and OP-INTENSIFY as well, and many believed that it was possible to use it without being cheap.

Since the removal of PLUS and OP-I in later games, players were no longer granted the special abilities listed above. As for being overweight, it is possible to go beyond weight limits, but the increased weight will slow down an AC's speed greatly, depending on the distance from those limits. However, in Armored Core 4 an AC cannot be deployed if it exceeds its weight limit and there are no secret enhancements that can be unlocked by the player.
[edit] Stabilizers (Armored Core 4)

Stabilizers are small add-ons that can be put on the frame parts of an AC. They are used to offset center of gravity of an AC unit for better control; because AC's are not always symmetrical, stabilizers are almost always needed on a design. Stabilizers have low weight and energy drain, but still hamper a design's stability, energy supply, turning speed, and so on, depending on how many are equipped.

Boost speed and turning are affected by the center of gravity, so a back-heavy AC will be able to move forward faster, and an AC that is heavy on the left will boost and turn to the left faster, but boost and turn slowly to the right. Because of this, close-range designs will forgo moving backwards and put a number of powerful stabilizers on their back so they can close in quickly; designs that use weapons that are dropped quickly will equip stabilizers so the AC is centered when the part is dropped.

Stabilizers can be manually equipped to an AC. If a player doesn't want to manually equip his/her AC with stabilizers, they can choose an option that automatically adds stabilizers to the AC.

Rabu, 05 Agustus 2009

Bintang

Bintang


Untuk kegunaan lain dari Bintang, lihat Bintang (disambiguasi)

Gugus bintang Pleiades, sebuah gugus terbuka di rasi Taurus.

Bintang merupakan benda langit yang memancarkan cahaya. Terdapat bintang semu dan bintang nyata. Bintang semu adalah bintang yang tidak menghasilkan cahaya sendiri, tetapi memantulkan cahaya yang diterima dari bintang lain. Bintang nyata adalah bintang yang menghasilkan cahaya sendiri. Secara umum sebutan bintang adalah objek luar angkasa yang menghasilkan cahaya sendiri (bintang nyata).

Menurut ilmu astronomi, definisi bintang adalah:
“ Semua benda masif (bermassa antara 0,08 hingga 200 massa matahari) yang sedang dan pernah melangsungkan pembangkitan energi melalui reaksi fusi nuklir. ”

Oleh sebab itu bintang katai putih dan bintang netron yang sudah tidak memancarkan cahaya atau energi tetap disebut sebagai bintang. Bintang terdekat dengan Bumi adalah Matahari pada jarak sekitar 149,680,000 kilometer, diikuti oleh Proxima Centauri dalam rasi bintang Centaurus berjarak sekitar empat tahun cahaya.
Daftar isi
[sembunyikan]

* 1 Sejarah Pengamatan
* 2 Radiasi
o 2.1 Fluks pancaran
o 2.2 Luminositas
o 2.3 Magnitudo
* 3 Satuan pengukuran
* 4 Klasifikasi
* 5 Penampakan dan Distribusi
* 6 Evolusi
o 6.1 Terbentuknya bintang
o 6.2 Deret Utama
o 6.3 Akhir sebuah bintang
* 7 Catatan kaki
* 8 Daftar pustaka
* 9 Pranala luar

Sejarah Pengamatan

Bintang-bintang telah menjadi bagian dari setiap kebudayaan. Bintang-bintang digunakan dalam praktek-praktek keagamaan, dalam navigasi, dan bercocok tanam. Kalender Gregorian, yang digunakan hampir di semua bagian dunia, adalah kalender matahari, mendasarkan diri pada posisi Bumi relatif terhadap bintang terdekat, Matahari.

Astronom-astronom awal seperti Tycho Brahe berhasil mengenali ‘bintang-bintang baru’ di langit (kemudian dinamakan novae) menunjukkan bahwa langit tidaklah kekal. Pada 1584 Giordano Bruno mengusulkan bahwa bintang-bintang sebenarnya adalah matahari-matahari lain, dan mungkin saja memiliki planet-planet seperti bumi di dalam orbitnya,[1] ide yang telah diusulkan sebelumnya oleh filsuf-filsuf Yunani kuno seperti Democritus dan Epicurus.[2] Pada abad berikutnya, ide bahwa bintang adalah matahari yang jauh mencapai konsensus di antara para astronom. Untuk menjelaskan mengapa bintang-bintang ini tidak memberikan tarikan gravitasi pada tata surya, Isaac Newton mengusulkan bahwa bintang-bintang terdistribusi secara merata di seluruh langit, sebuah ide yang berasal dari teolog Richard Bentley.[3]

Astronom Italia Geminiano Montanari merekam adanya perubahan luminositas pada bintang Algol pada 1667. Edmond Halley menerbitkan pengukuran pertama gerak diri dari sepasang bintang “tetap” dekat, memperlihatkan bahwa mereka berubah posisi dari sejak pengukuran yang dilakukan Ptolemaeus dan Hipparchus. Pengukuran langsung jarak bintang 61 Cygni dilakukan pada 1838 oleh Friedrich Bessel menggunakan teknik paralaks.

William Herschel adalah astronom pertama yang mencoba menentukan distribusi bintang di langit. Selama 1780an ia melakukan pencacahan di sekitar 600 daerah langit berbeda. Ia kemudian menyimpulkan bahwa jumlah bintang bertambah secara tetap ke suatu arah langit, yakni pusat galaksi Bima Sakti. Putranya John Herschel mengulangi pekerjaan yang sama di hemisfer langit sebelah selatan dan menemukan hasil yang sama.[4] Selain itu William Herschel juga menemukan bahwa beberapa pasangan bintang bukanlah bintang-bintang yang secara kebetulan berada dalam satu arah garis pandang, melainkan mereka memang secara fisik berpasangan membentuk sistem bintang ganda.

Radiasi

Energi yang dihasilkan bintang, sebagai hasil samping dari reaksi fusi nuklir, dipancarkan ke luar angkasa sebagai radiasi elektromagnetik dan radiasi partikel. Radiasi partikel yang dipancarkan bintang dimanifestasikan sebagai angin bintang (yang berwujud sebagai pancaran tetap partikel-partikel bermuatan listrik seperti proton bebas, partikel alpha dan partikel beta yang berasal dari bagian terluar bintang) dan pancaran tetap neutrino yang berasal dari inti bintang.

Hampir semua informasi yang kita miliki mengenai bintang yang lebih jauh dari Matahari diturunkan dari pengamatan radiasi elektromagnetiknya, yang terentang dari panjang gelombang radio hingga sinar gamma. Namun tidak semua rentang panjang gelombang tersebut dapat diterima oleh teleskop landas Bumi. Hanya gelombang radio dan gelombang cahaya yang dapat diteruskan oleh atmosfer Bumi dan menciptakan ‘jendela radio’ dan ‘jendela optik’. Teleskop-teleskop luar angkasa telah diluncurkan untuk mengamati bintang-bintang pada panjang gelombang lain.

Banyaknya radiasi elektromagnetik yang dipancarkan oleh bintang dipengaruhi terutama oleh luas permukaan, suhu dan komposisi kimia dari bagian luar (fotosfer) bintang tersebut. Pada akhirnya kita dapat menduga kondisi di bagian dalam bintang, karena apa yang terjadi di permukaan pastilah sangat dipengaruhi oleh bagian yang lebih dalam.

Dengan menelaah spektrum bintang, astronom dapat menentukan temperatur permukaan, gravitasi permukaan, metalisitas, dan kecepatan rotasi dari sebuah bintang. Jika jarak bisa ditentukan, misal dengan metode paralaks, maka luminositas bintang dapat diturunkan. Massa, radius, gravitasi permukaan, dan periode rotasi kemudian dapat diperkirakan dari pemodelan. Massa bintang dapat juga diukur secara langsung untuk bintang-bintang yang berada dalam sistem bintang ganda atau melalui metode mikrolensing. Pada akhirnya astronom dapat memperkirakan umur sebuah bintang dari parameter-parameter di atas.

Fluks pancaran

Kuantitas yang pertama kali langsung dapat ditentukan dari pengamatan sebuah bintang adalah fluks pancarannya, yaitu jumlah cahaya atau energi yang diterima permukaan kolektor (mata atau teleskop) per satuan luas per satuan waktu. Biasanya dinyatakan dalam satuan watt per cm2 (satuan internasional) atau erg per detik per cm2 (satuan cgs).

[sunting] Luminositas

Di dalam astronomi, luminositas adalah jumlah cahaya atau energi yang dipancarkan oleh sebuah bintang ke segala arah per satuan waktu. Biasanya satuan luminositas dinyatakan dalam watt (satuan internasional), erg per detik (satuan cgs) atau luminositas matahari. Dengan menganggap bahwa bintang adalah sebuah benda hitam sempurna, maka luminositasnya adalah,

L = 4 \pi R^2 \sigma T_{e}^4

dimana L adalah luminositas, σ adalah tetapan Stefan-Boltzmann, R adalah jari-jari bintang dan Te adalah temperatur efektif bintang.

Jika jarak bintang dapat diketahui, misalnya dengan menggunakan metode paralaks, luminositas sebuah bintang dapat ditentukan melalui hubungan

E = \frac {L} {4 \pi d^2}

dengan E adalah fluks pancaran, L adalah luminositas dan d adalah jarak bintang ke pengamat.

Magnitudo

Secara tradisi kecerahan bintang dinyatakan dalam satuan magnitudo. Kecerahan bintang yang kita amati, baik menggunakan mata bugil maupun teleskop, dinyatakan oleh magnitudo tampak (m) atau magnitudo semu. Secara tradisi magnitudo semu bintang yang dapat dilihat oleh mata bugil dibagi dari 1 hingga 6, di mana satu ialah bintang paling cerah, dan 6 sebagai bintang paling redup. Terdapat juga kecerahan yang diukur secara mutlak, yang menyatakan kecerahan bintang sebenarnya. Kecerahan ini dikenal sebagai magnitudo mutlak (M), dan terentang antara +26.0 sampai -26.5. Magnitudo adalah besaran lain dalam menyatakan fluks pancaran, yang terhubungkan melalui persamaan,

m = -2,5 \log(E) + konstanta \,\!

dimana m adalah magnitudo semu dan E adalah fluks pancaran.

Satuan pengukuran

Kebanyakan parameter-parameter bintang dinyatakan dalam satuan SI, tetapi satuan cgs kadang-kadang digunakan (misalnya luminositas dinyatakan dalam satuan erg per detik). Penggunaan satuan cgs lebih bersifat tradisi daripada sebuah konvensi. Seringkali pula massa, luminositas dan jari-jari bintang dinyatakan dalam satuan matahari, mengingat Matahari adalah bintang yang paling banyak dipelajari dan diketahui parameter-parameter fisisnya. Untuk Matahari, parameter-parameter berikut diketahui:

massa Matahari: M_\bigodot = 1.9891 \times 10^{30} kg[5]
luminositas Matahari: L_\bigodot = 3.827 \times 10^{26} watt[5]
radius Matahari: R_\bigodot = 6.960 \times 10^{8} m[6]

Skala panjang seperti setengah sumbu besar dari sebuah orbit sistem bintang ganda seringkali dinyatakan dalam satuan astronomi (AU = astronomical unit), yaitu jarak rata-rata antara Bumi dan Matahari.

Klasifikasi

!Artikel utama untuk bagian ini adalah: Klasifikasi bintang

Berdasarkan spektrumnya, bintang dibagi ke dalam 7 kelas utama yang dinyatakan dengan huruf O, B, A, F, G, K, M yang juga menunjukkan urutan suhu, warna dan komposisi-kimianya. Klasifikasi ini dikembangkan oleh Observatorium Universitas Harvard dan Annie Jump Cannon pada tahun 1920an dan dikenal sebagai sistem klasifikasi Harvard. Untuk mengingat urutan penggolongan ini biasanya digunakan kalimat "Oh Be A Fine Girl Kiss Me". Dengan kualitas spektrogram yang lebih baik memungkinkan penggolongan ke dalam 10 sub-kelas yang diindikasikan oleh sebuah bilangan (0 hingga 9) yang mengikuti huruf. Sudah menjadi kebiasaan untuk menyebut bintang-bintang di awal urutan sebagai bintang tipe awal dan yang di akhir urutan sebagai bintang tipe akhir. Jadi, bintang A0 bertipe lebih awal daripada F5, dan K0 lebih awal daripada K5.
Kelas Warna Suhu Permukaan °C Contoh
O Biru > 25,000 Spica
B Putih-Biru 11.000 - 25.000 Rigel
A Putih 7.500 - 11.000 Sirius
F Putih-Kuning 6.000 - 7.500 Procyon A
G Kuning 5.000 - 6.000 Matahari
K Jingga 3.500 - 5.000 Arcturus
M Merah <3,500 Betelgeuse

Pada tahun 1943, William Wilson Morgan, Phillip C. Keenan, dan Edith Kellman dari Observatorium Yerkes menambahkan sistem pengklasifikasian berdasarkan kuat cahaya atau luminositas, yang seringkali merujuk pada ukurannya. Pengklasifikasian tersebut dikenal sebagai sistem klasifikasi Yerkes dan membagi bintang ke dalam kelas-kelas berikut :

* 0 Maha maha raksasa
* I Maharaksasa
* II Raksasa-raksasa terang
* III Raksasa
* IV Sub-raksasa
* V deret utama (katai)
* VI sub-katai
* VII katai putih

Umumnya kelas bintang dinyatakan dengan dua sistem pengklasifikasian di atas. Matahari kita misalnya, adalah sebuah bintang dengan kelas G2V, berwarna kuning, bersuhu dan berukuran sedang.

Diagram Hertzsprung-Russell adalah diagram hubungan antara luminositas dan kelas spektrum (suhu permukaan) bintang. Diagram ini adalah diagram paling penting bagi para astronom dalam usaha mempelajari evolusi bintang.

Penampakan dan Distribusi

Karena jaraknya yang sangat jauh, semua bintang (kecuali Matahari) hanya tampak sebagai titik saja yang berkelap-kelip karena efek turbulensi atmosfer Bumi. Diameter sudut bintang bernilai sangat kecil ketika diamati menggunakan teleskop optik landas bumi, hingga diperlukan teleskop interferometer untuk dapat memperoleh citranya. Bintang dengan ukuran diameter sudut terbesar setelah Matahari adalah R Doradus, dengan 0,057 detik busur.
Sebuah katai putih yang sedang mengorbit Sirius (konsep artis). citra NASA.

Telah lama dikira bahwa kebanyakan bintang berada pada sistem bintang ganda atau sistem multi bintang. Kenyataan ini hanya benar untuk bintang-bintang masif kelas O dan B, dimana 80% populasinya dipercaya berada dalam suatu sistem bintang ganda atau pun multi bintang. Semakin redup bintang, semakin besar kemungkinannya dijumpai sebagai sistem tunggal. Dijumpai hanya 25% populasi katai merah yang berada dalam sebuah sistem bintang ganda atau sistem multi bintang. Karena 85% populasi bintang di galaksi Bimasakti adalah katai merah, maka tampaknya kebanyakan bintang di dalam Bimasakti berada pada sistem bintang tunggal.

Sistem yang lebih besar yang disebut gugus bintang juga dijumpai. Bintang-bintang tidak tersebar secara merata mengisi seluruh ruang alam semesta, tetapi terkelompokkan ke dalam galaksi-galaksi bersama-sama dengan gas antarbintang dan debu. Sebuah galasi tipikal mengandung ratusan miliar bintang, dan terdapat lebih dari 100 miliar galaksi di seluruh alam semesta teramati.[7]

Astronom memperkirakan terdapat 70 sekstiliun (7×1022) bintang di seluruh alam semesta yang teramati[8]. Ini berarti 70 000 000 000 000 000 000 000 bintang, atau 230 miliar kali banyaknya bintang di galaksi Bimasakti yang berjumlah sekitar 300 miliar.

Bintang terdekat dengan Matahari adalah Proxima Centauri, berjarak 39.9 triliun (1012) kilometer, atau 4.2 tahun cahaya. Cahaya dari Proxima Centauri memakan waktu 4.2 tahun untuk mencapai Bumi. Jarak ini adalah jarak antar bintang tipikal di dalam sebuah piringan galaksi. Bintang-bintang dapat berada pada jarak yang lebih dekat satu sama lain di daerah sekitar pusat galasi dan di dalam gugus bola, atau pada jarak yang lebih jauh di halo galaksi.

Karena kerapatan yang rendah di dalam sebuah galaksi, tumbukan antar bintang jarang terjadi. Namun di daerah yang sangat padat seperti di inti sebuah gugus bintang atau lingkungan sekitar pusat galaksi, tumbukan dapat sering terjadi[9] . Tumbukan seperti ini dapat menghasilkan pengembara-pengembara biru yaitu sebuah bintang abnormal hasil penggabungan yang memiliki temperatur permukaan yang lebih tinggi dibandingkan bintang deret utama lainnya di sebuah gugus bintang dengan luminositas yang sama. Istilah pengembara merujuk pada jejak evolusi yang berbeda dengan bintang normal lainnya pada diagram Hertzsprung-Russel.

[sunting] Evolusi

Struktur, evolusi, dan nasib akhir sebuah bintang sangat dipengaruhi oleh massanya. Selain itu, komposisi kimia juga ikut mengambil peran dalam skala yang lebih kecil.

Terbentuknya bintang

Bintang terbentuk di dalam awan molekul; yaitu sebuah daerah medium antarbintang yang luas dengan kerapatan yang tinggi (meskipun masih kurang rapat jika dibandingkan dengan sebuah vacuum chamber yang ada di bumi). Awan ini kebanyakan terdiri dari hidrogen dengan sekitar 23–28% helium dan beberapa persen elemen berat. Komposisi elemen dalam awan ini tidak banyak berubah sejak peristiwa nukleosintesis Big Bang pada saat awal alam semesta.

Gravitasi mengambil peranan sangat penting dalam proses pembentukan bintang. Pembentukan bintang dimulai dengan ketidakstabilan gravitasi di dalam awan molekul yang dapat memiliki massa ribuan kali matahari. Ketidakstabilan ini seringkali dipicu oleh gelombang kejut dari supernova atau tumbukan antara dua galaksi. Sekali sebuah wilayah mencapai kerapatan materi yang cukup memenuhi syarat terjadinya instabilitas Jeans, awan tersebut mulai runtuh di bawah gaya gravitasinya sendiri.

Berdasarkan syarat instabilitas Jeans, bintang tidak terbentuk sendiri-sendiri, melainkan dalam kelompok yang berasal dari suatu keruntuhan di suatu awan molekul yang besar, kemudian terpecah menjadi konglomerasi individual. Hal ini didukung oleh pengamatan dimana banyak bintang berusia sama tergabung dalam gugus atau asosiasi bintang.

Begitu awan runtuh, akan terjadi konglomerasi individual dari debu dan gas yang padat yang disebut sebagai globula Bok. Globula Bok ini dapat memiliki massa hingga 50 kali Matahari. Runtuhnya globula membuat bertambahnya kerapatan. Pada proses ini energi gravitasi diubah menjadi energi panas sehingga temperatur meningkat. Ketika awan protobintang ini mencapai kesetimbangan hidrostatik, sebuah protobintang akan terbentuk di intinya. Bintang pra deret utama ini seringkali dikelilingi oleh piringan protoplanet. Pengerutan atau keruntuhan awan molekul ini memakan waktu hingga puluhan juta tahun. Ketika peningkatan temperatur di inti protobintang mencapai kisaran 10 juta kelvin, hidrogen di inti 'terbakar' menjadi helium dalam suatu reaksi termonuklir. Reaksi nuklir di dalam inti bintang menyuplai cukup energi untuk mempertahankan tekanan di pusat sehingga proses pengerutan berhenti. Protobintang kini memulai kehidupan baru sebagai bintang deret utama.

Deret Utama

Bintang menghabiskan sekitar 90% umurnya untuk membakar hidrogen dalam reaksi fusi yang menghasilkan helium dengan temperatur dan tekanan yang sangat tinggi di intinya. Pada fase ini bintang dikatakan berada dalam deret utama dan disebut sebagai bintang katai.

Akhir sebuah bintang

Ketika kandungan hidrogen di teras bintang habis, teras bintang mengecil dan membebaskan banyak panas dan memanaskan lapisan luar bintang. Lapisan luar bintang yang masih banyak hidrogen mengembang dan bertukar warna merah dan disebut bintang raksaksa merah yang dapat mencapai 100 kali ukuran matahari sebelum membentuk bintang kerdil putih. Sekiranya bintang tersebut berukuran lebih besar dari matahari, bintang tersebut akan membentuk superraksaksa merah. Superraksaksa merah ini kemudiannya membentuk Nova atau Supernova dan kemudiannya membentuk bintang neutron atau Lubang hitam.