astronomy

HE 1104−1805

HE 1104−1805 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 HE 1104−1805 rather than just read about it. In short: HE 1104−1805 known as CTS 463 or Double Hamburger in literature, is a gravitationally-lensed quasar located in the constellation of Crater. It has a redshift of (z) 2.32 and it was first discovered by astronomers L.

Key takeaways

HE 1104−1805 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect HE 1104−1805 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HE 1104−1805 from memory before moving on to harder problems.

Reference excerpt

HE 1104−1805 known as CTS 463 or Double Hamburger in literature, is a gravitationally-lensed quasar located in the constellation of Crater. It has a redshift of (z) 2.32 and it was first discovered by astronomers L. Wisotzki, T. Koehler, R. Kayser and D. Reimers in October 1993. This quasar is classified as radio-quiet.

Description HE 1104−1805 is classified as a double quasar with an angular separation of 3.0 arcseconds and estimated B magnitudes of 16.70 and 18.74. When imaged, the quasar is found separated into two components, with the A component displaying emission lines of lower width, and a bluer continuum. It is found lensed by a foreground early-type galaxy described as large with a mass of 7 × 1011 M☉. The redshift of the lens galaxy is (z) 0.729 ± 0.001 based on observations with the Very Large Telescope by C. Lidman while dismissing other redshift estimates of the galaxy at (z) 0.77 by C.Y. Peng based on the assumption of a fundamental plane measurement made by C.S. Kochanek and at (z) 1.66 by F. Courbin. Combined observations with the Wise Observatory and by Schechter found the two images of HE 1104−1805 display time-delays. Based on results, the time delays are significantly shorter with a period of -161 ± 7 days while others estimated the time-delays between the ranges of -129 and -263 h−1 days, 0.73 years via a quantitative analysis, and between -0.9 and -0.7 years. Another study estimated an interband centroid time-delay of -4.3+3.1-3.4 days. Evidence also showed the light curves of the two images displaying a long-term variability trend, indicating it was caused by microlensing from the stars of the lens galaxy. Substantial variations were also noted in these images, although the B image has less fluctuations compared to the A image mainly because of the high dark matter concentration and low stellar surface density. Monitoring campaign observations made with Chandra X-ray Observatory in 2009, also detected the flux variability of the A image of HE 1104–1805 has a high amplitude in X-rays. As the variability is uncorrelated, this indicates microlensing. The host galaxy of HE 1104−1805 is described as shaped into an Einstein Ring. It has a dusty appearance or little star formation based on scaling and addition of its arc imaging to both I and V images. Observations also pointed out the carbon oxide emission are found associated with the AGN's two point-like imaging with offset emission peaks. This suggests the AGN is not located in the molecular gas reservoir. The central supermassive black hole of HE 1104−1805 is estimated to be 2.4 × 109 M☉. Other studies estimated the black hole mass as 9.37 ± 0.33, 8.77 ± 30 and 9.05 ± 0.23 based on estimation of its emission line widths. Several rich metallic systems of absorption lines have also been identified in the quasar's spectra with these lines being located at (z) 1.662, (z) 0.728 and (z) 1.320.

Gallery

References

Illustrations

Worked examples

Example 1 — a first encounter with HE 1104−1805

Start with the simplest possible case. Write down what HE 1104−1805 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 HE 1104−1805 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 HE 1104−1805 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 HE 1104−1805

In research: HE 1104−1805 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 HE 1104−1805 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: HE 1104−1805 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Active galaxies, Crater (constellation), Gravitationally lensed quasars, so understanding it makes those chapters shorter.
In everyday life: Look for HE 1104−1805 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 HE 1104−1805 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HE 1104−1805 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 HE 1104−1805 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HE 1104−1805 in simple terms?

Why does HE 1104−1805 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 HE 1104−1805?

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 HE 1104−1805.