HH 30

Key takeaways

HH 30 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect HH 30 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HH 30 from memory before moving on to harder problems.

Reference excerpt

HH-30 (also V1213 Tauri) is an edge-on protoplanetary disk located about 146.4 parsecs from Earth that is surrounded by jets and a disk wind. HH-30 is located in the dark cloud LDN 1551 in the Taurus Molecular Cloud. The HH-30 disk is the prototype of an edge-on disk, due to its early discovery with Hubble. The object has been subject to many studies due to a wealth of dynamical processes that are happening to HH-30.

Discovery HH 30 was published by George Herbig in 1974 in the "Draft Catalog of Herbig–Haro Objects" and notes: "HH-30 (4h 28m 44s) is a small, almost stellar spot 2' south of XZ and HL Tau. There is a fainter nebulosity immediately northeast. The small fuzzy spot of very similar appearance at 35" in 250° from HL Tau is not a HH Object, but a star having Hα in emission." In 1996 it became clear that the object is an edge-on protoplanetary disk with jets.

The central star The star is hidden behind the dust of the disk. The spectral type was measured around M0 with the Keck Observatory, corresponding to a temperature of around 3700 Kelvin. Disk rotation constrained the star mass to 0.45 M☉. One study suggest that the central object is a binary star, due to the jet wiggling. A follow-up study found that the jet-producing primary has a mass of 0.31 ±0.04 M☉ and that the secondary has a mass of 0.14 ±0.03 M☉. Both objects should be separated by 18.0 ±0.6 astronomical units (AU).

Protoplanetary disk Observations with Hubble WFPC2 in 1996 discovered the disk, which has a radius of 250 AU. The disk is seen as a bi-reflection nebula and the disk blocks the light of the star. The northern part of the reflection nebula decreased in brightness by 0.5 mag between two observations, while the southern part increased in brightness by 0.5 mag. The disk around the star is a class II disk, meaning it contains both gas and dust particles. Observations with the Plateau de Bure interferometer detected the carbon monoxide (CO) emission and measured the rotation of the disk. Observations with the Atacama Large Millimeter Array (ALMA) showed the mid-plane of the disk in 13CO and also measured its rotation. A study with JWST and archived Hubble and ALMA data was published in 2024. This showed inefficient dust settling in the disk. Dust settling means that larger dust grains settle to the mid-plane of the disk. The observation also showed that the disk contains spiral-like and tail-like structure. The disk has a very high inclination of at least 84°.

Jets The jets were discovered in 1983 from CCD images at Calar Alto Observatory. A proper motion survey in 1990 showed a speed of around 170 km/s of the jets. This study also detected H-alpha, ionized nitrogen and sulfur in the jet. Early observations with Hubble showed that the knots of the jet have a speed of 100 to 300 km/s. JWST NIRCam and MIRI observations showed the previously observed jet and a bi-conical outflow. The jet is bright in the MIRI F1280W filter, likely tracing ionized neon emission. One knot was seen moving with around 121 km/s. The jet is seen with NIRSpec in ionized iron with a tight semi-opening angle of 1.4°±0.9°.

Disk wind A CO outflow was first resolved in 2006, and in 2024 the outflow was detected with ALMA in 12CO. The researchers found three distinct shells in the outflow and measured an outflow mass of (1.83 ±0.19)×10‑4 M☉. This outflow is expanding with a speed of around 4–6 km/s and possibly rotates with a speed of ≤0.5 km/s. These shells can be explained by a magnetocentrifugal disk winds (MHD wind). Another study using NIRSpec and ALMA, found that the outflow is nestled within each other. The jet is seen with a tight semi-opening angle of around 1.4°. The disk wind is seen with a wider semi-opening angle, with the molecular hydrogen (H2) emission having a semi-opening angle of around 14°. But this emission is also nestled within cold carbon monoxide (CO) emission from ALMA.

See also List of resolved circumstellar disks Examples of other edge-on disks:

Beta Pictoris (debris disks) AU Microscopii (debris disks) HD 106906 (debris disk) Dracula's Chivito (protoplanetary) Gomez's Hamburger (protoplanetary) HK Tauri B (protoplanetary) 2MASS J04202144+2813491 (protoplanetary)

Gallery

References

External links Hubble Observes the Fire and Fury of a Stellar Birth original press-release from 1995 describing the observations of HH 30 and other Herbig-Haro objects Winds of change: James Webb Space Telescope reveals elusive details in young star systems press-release of a MPIA study that also studied HH 30

Illustrations

Worked examples

Example 1 — a first encounter with HH 30

Start with the simplest possible case. Write down what HH 30 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 HH 30 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 HH 30 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 HH 30

In research: HH 30 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 HH 30 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: HH 30 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1974, Circumstellar disks, M-type main-sequence stars, so understanding it makes those chapters shorter.
In everyday life: Look for HH 30 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 HH 30 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HH 30 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 HH 30 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HH 30 in simple terms?

HH-30 (also V1213 Tauri) is an edge-on protoplanetary disk located about 146.4 parsecs from Earth that is surrounded by jets and a disk wind. HH-30 is located in the dark cloud LDN 1551 in the Taurus Molecular Cloud.

Why does HH 30 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 HH 30?

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 HH 30.