HIP 79098

Key takeaways

HIP 79098 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect HIP 79098 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HIP 79098 from memory before moving on to harder problems.

Reference excerpt

HIP 79098 is a binary star in the constellation Scorpius. It has a visual apparent magnitude of about +5.9, being visible to the naked eye under very dark skies. From parallax measurements by the Gaia spacecraft, it is located approximately 500 light-years (154 parsecs) from Earth. This system consists of a chemically peculiar B-type star, plus a spectroscopic companion of unknown type. Two additional distant red dwarfs may be part of the system, at separations of 9,500 and 12,900 AU. In 2019, a brown dwarf was discovered orbiting the central binary at a distance of about 350 AU.

Star system This is a young stellar system, belonging to the Upper Scorpius subgroup of the Scorpius–Centaurus association, the nearest OB association to the Sun. This is an association of stars with common origin and movement. The Upper Scorpius subgroup is the youngest of the association and has an estimated age of around 10 million years, which is therefore the age of HIP 79098. HIP 79098 has a spectral type of B9V, indicating that the primary star is a B-type main sequence star. The system's spectrum is complex and has also been classified as B9 Mn P Ga, and B9IVn+Ap(Si)s. The primary is a chemically peculiar star of the type HgMn (mercury-manganese star), and has strong manganese and gallium lines, and weak helium lines. It is also a variable star, oscillating between magnitudes 5.87 and 5.90 with a period of 2.69 days, being classified as a α2 Canum Venaticorum variable. A secondary period of 0.28 days has also been detected. These variability cycles can be caused by the rotation of the star or by pulsations. The mass of the primary star is estimated at 2.5 times the solar mass. The system's spectrum has the lines of a second star, which means HIP 79098 is a double-lined spectroscopic binary. While its exact nature is unknown, the secondary star is probably quite massive, possibly almost as massive as the primary. The primary's radial velocity seems to have large variations caused by the orbit of the stars, but different studies give contradictory results regarding the size of these variations, so it is not possible to determine the basic parameters of the system like masses and orbit. The presence of the second star is also seen in the astrometic data by the Hipparcos and Gaia spacecraft, which show a large anomaly from the constant proper motion hypothesis. One 2023 study of the radial velocity and astrometric data found a semi-major axis of 1.9±0.6 au and a companion mass of 0.53±0.26 M☉. There are two other stars close to HIP 79098 in the sky which have proper motion and distances similar to those of HIP 79098, and therefore can be physical companions. They are both low-mass red dwarfs and are also confirmed members of the Scorpius–Centaurus association. The first star has a spectral type of M5 and is separated from HIP 79098 by 65 arcseconds, or 9,500 AU. The second star is brighter and has a spectral type of M3.25, and is separated by 88 arcseconds, or 12,900 AU.

Brown dwarf

The discovery of a brown dwarf orbiting HIP 79098 was published in 2019 as part of the BEAST survey, which searches for planets around B-type stars in the Scorpius–Centaurus association. This object was identified in archival images from 2000 by the ESO 3.6 m Telescope, from 2004 by NACO instrument at the Very Large Telescope, and from 2015 by the SPHERE instrument at the Very Large Telescope. Previous studies had seen the object, but considered it too red to be part of the HIP 79098 system, so it was rejected as a likely background star. The 2019 study combined all the observations of the object and showed that it has a common proper motion with HIP 79098, confirming that it is physically linked to the system. Named HIP 79098 (AB)b, the brown dwarf is circumbinary and was observed at a separation of 2.4 arcseconds from the central binary, or 345±6 AU. Its color is redder than expected for an object of its luminosity, which is expected given the young age of the system and explains why HIP 79098 (AB)b was not found in the earlier studies. Its color and luminosity are consistent with a spectral type of M9–L0, its mass is 15–26 times the mass of Jupiter, and effective temperature 2,300 to 2,600 K. The mass ratio between HIP 79098 (AB)b and the central binary is estimated at 0.3–1%. This is a low value similar to some systems with massive planets, which can suggest that HIP 79098 (AB)b represents the upper end of the planet population, as opposed to having been formed as a star.

References

Illustrations

Worked examples

Example 1 — a first encounter with HIP 79098

Start with the simplest possible case. Write down what HIP 79098 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 HIP 79098 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 HIP 79098 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 HIP 79098

In research: HIP 79098 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 HIP 79098 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: HIP 79098 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Alpha2 Canum Venaticorum variables, B-type main-sequence stars, Bright Star Catalogue objects, so understanding it makes those chapters shorter.
In everyday life: Look for HIP 79098 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.

How to study HIP 79098 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HIP 79098 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 HIP 79098 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HIP 79098 in simple terms?

HIP 79098 is a binary star in the constellation Scorpius. It has a visual apparent magnitude of about +5.9, being visible to the naked eye under very dark skies.

Why does HIP 79098 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 HIP 79098?

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 HIP 79098.