astronomy

Iota Draconis

Iota Draconis is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Iota Draconis rather than just read about it. In short: Iota Draconis (ι Draconis, abbreviated Iota Dra, ι Dra), also named Edasich , is a star in the northern circumpolar constellation of Draco. A visually unremarkable star of apparent magnitude 3.3, in 2002 it was discovered to have a planet orbiting it (designated Iota Draconis b, later named Hypatia).

Key takeaways

Iota Draconis belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Iota Draconis to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Iota Draconis from memory before moving on to harder problems.

Reference excerpt

Iota Draconis (ι Draconis, abbreviated Iota Dra, ι Dra), also named Edasich , is a star in the northern circumpolar constellation of Draco. A visually unremarkable star of apparent magnitude 3.3, in 2002 it was discovered to have a planet orbiting it (designated Iota Draconis b, later named Hypatia). From parallax measurements, this star is located at a distance of about 101.2 light-years (31.0 parsecs) from the Sun.

Nomenclature ι Draconis (Latinised to Iota Draconis) is the star's Bayer designation. On discovery the planet was designated Iota Draconis b (or Edasich b). It bore the traditional name Edasich, derived from the Arabic Al Ḍhiba' of Ulugh Beg and the Dresden Globe, or Al dhīlī 'Male hyena' by Kazwini, with Eldsich being recorded in the Century Cyclopedia. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included Edasich for this star. In July 2014 the International Astronomical Union launched NameExoWorlds, a process for giving proper names to certain exoplanets and their host stars. The process involved public nomination and voting for the new names. In December 2015, the IAU announced the winning name was Hypatia for this planet. The winning name was submitted by Hypatia, a student society of the Physics Faculty of the Universidad Complutense de Madrid, Spain. Hypatia was a famous Greek astronomer, mathematician, and philosopher. In Chinese, 紫微左垣 (Zǐ Wēi Zuǒ Yuán), meaning Left Wall of Purple Forbidden Enclosure, refers to an asterism consisting of Iota Draconis, Theta Draconis, Eta Draconis, Zeta Draconis, Upsilon Draconis, 73 Draconis, Gamma Draconis and 23 Cassiopeiae. Consequently, the Chinese name for Iota Draconis itself is 紫微左垣一 (Zǐ Wēi Zuǒ Yuán yī, English: the First Star of Left Wall of Purple Forbidden Enclosure), representing 左樞 (Zuǒshū), meaning Left Pivot. 左樞 (Zuǒshū) is westernized into Tsao Choo by R.H. Allen with the same meaning

Properties Iota Draconis is larger and more massive than the Sun, with 1.6 times the mass and nearly 12 times the radius. The spectrum matches a stellar classification of K2 III, indicating this is an evolved star that has exhausted the supply of hydrogen at its core and left the main sequence. It is currently on the red giant branch, fusing hydrogen in a shell around its helium core. With an expanded outer envelope, it is radiating over 50 times the luminosity of the Sun at an effective temperature of 4,504 K. This temperature gives it an orange hue that is a characteristic of K-type stars. It is rotating at a leisurely rate, with a period of around 434 days. It is about 2.5 billion years old. In the past Iota Draconis has been suspected of variability. However, the star has been found to have a constant luminosity to within about 0.004 magnitudes. Hence, as of 2010, the variability remains unconfirmed. An excess emission of infrared radiation at a wavelength of 70μm suggests the presence of a circumstellar disk of dust; what astronomers term a debris disk. Edasich is the faintest star of which a color has been reported in pre-telescopic times. It was classified as an orange-red star.

Planetary system

The planetary companion discovered in 2002 was the first planet known to orbit a giant star. It was noted that the alignment of this planet's eccentric orbit means it has about 11% probability of transiting its star. Another long-period planet or brown dwarf was discovered in 2021, and the true masses of both planets were measured via astrometry.

References

External links Extrasolar Planets Encyclopaedia: Notes for star HIP 75458 SolStation: Edasich/Iota Draconis

Illustrations

Worked examples

Example 1 — a first encounter with Iota Draconis

Start with the simplest possible case. Write down what Iota Draconis claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Iota Draconis before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Iota Draconis ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Iota Draconis

In research: Iota Draconis appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Iota Draconis in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Iota Draconis is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bayer objects, Bright Star Catalogue objects, Circumstellar disks, so understanding it makes those chapters shorter.
In everyday life: Look for Iota Draconis outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Iota Draconis in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Iota Draconis means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Iota Draconis out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Iota Draconis in simple terms?

Why does Iota Draconis matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Iota Draconis?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Iota Draconis.