How do stellar telescopes work

Starting Nov. Help us create experiences of awe and wonder with the Astronomy Discovery Center, opening by They also forge most of the heavier elements: the carbon in your body and the oxygen that your breathe were all made in the interiors of massive stars.

We use a combination of imaging and spectroscopy to determine the physical properties and populations of these stars, and compare their results with current stellar evolutionary theory. If the observations and theory match, we celebrate! The 6. The massive stars research group is privileged to be able to use this remarkable instrument in their studies of stars in the Large Magellanic Cloud, visible directly above the telescope in this picture by Kathryn Neugent.

Such stars have burned through their hydrogen and are now just hundreds of thousands of years away from exploding as supernovae. In particular, Neugent has better constrained the number of red supergiants that are in binary systems with a companion star. When she started this work a few years ago, there were only a dozen such systems known.

Using spectra obtained on the 6. She plans on continuing to study these systems, as well as single red supergiants that have possibly merged with their companions, using the LDT. Philip Massey is currently working on combining our knowledge of the stellar populations of the Wolf-Rayet and red supergiant populations as a diagnostic of the influence of binarity on massive star evolution. Evolutionary models predict very different results for the relative populations of these stars in nearby galaxies depending upon whether the WRs were stripped by stellar winds or as the result of binary interactions.

He is also using the Hubble Space Telescope to follow-up on a peculiar Wolf-Rayet binary star that he, Neugent, and other colleagues discovered several years ago in the Large Magellanic Cloud. These are stars whose spectra are characterized by broad, strong emission lines formed in outflowing stellar winds.

These are basically the bare cores of very massive stars, as their outer layers have been stripped away. She works on uncovering the answer by modeling the spectra of these stars.

The physical parameters we find through modeling can tell us whether Wolf-Rayet stars can evolve by themselves outer layers stripped solely by stellar winds or if they require a companion star.

Aadland also looks at spectra from different Wolf-Rayet phases to determine how these stars evolve right before they go supernova.

They are also the longest-lived stars, with lifetimes of 20 billion to billion years or more; their small sizes mean they burn through their nuclear fuel at a miserly rate, and they shine dimly but steadily. Given the degree to which these objects are ubiquitous throughout our Galaxy and others, M dwarfs are particularly interesting to astronomers as hosts of planets that could potentially bear life.

The small size of these stars means its somewhat easier to find those planets about them, further increasing their research appeal. Our group at Lowell has been working to characterize these objects — their sizes, distances, temperatures — which opens up insights into the stars as well as any planets they might host. A particular specialty here has been characterizing the multiplicity rate of these stars: roughly half of the stars in the sky have a second star next to them our own sun is a solo loner , and this could affect the planet hosting rate.

For low-mass stars this rate is somewhat lower, but it is not well-measured nor understood. Towards that end, he has specialized over the course of his career in the construction and use of ultra-high-spatial resolution instrumentation.

The empirical curve was then fit with the model described above. The RMS value was calculated to obtain a rough goodness of fit, but most of the work of retrying templates and tweaking smoothing parameters was done judiciously by eye. Our main result is to present spectra of 40 stars. The SNAP program is still active at low priority, so a few more stars may enter the library in the future. As best as can be contrived, the spectra are free of cosmic rays, red fringing in the GL, and scattered light in the case of our coolest stars.

Cross-correlation was used to bring the spectra to a zero velocity wavelength scale. Finally, a five-parameter dust extinction model, or one-parameter in the case of low-extinction stars, was fit using synthetic spectra as zero-extinction templates.

Three examples are illustrated in Fig. The spectra are available online 2. After the observations were reduced, we discovered a duplication. They arrived in the target list via different literature paths, with temperatures 12 K apart. Despite this, their separately-derived extinctions are only 0. In the process of fitting extinction curves with synthetic templates, the central star in NGC object 21 in our list was difficultto match.

The match improved, but was not good near H continuum breaks. This template problem may introduce a few hundredths magnitude error in A V.

A third of the PAGB stars show emission lines. A pair of resonance Mg II absorptions at In stars with chromospheres, it may also have an emission component Gurzadian et al. Example spectra. Spectra as observed blue and as extinction corrected black with errors flanking green curves.

The no-dust template synthetic spectrum magenta overlaps. Internal program identifications appear below the object name. We present low resolution spectra from 0. Honed stellar atmospheric parameters is another goal of the project. The library can be used for improving synthetic spectra, observational flux calibration, and even basic teaching about spectral types and stellar atmospheres.

Extensions to this project should include fitting the library and making stellar population models for integrated light similar to those of Vazdekis et al. At that point, the library will be applied to galaxy population synthesis. Due to its UV coverage, it will be uniquely applicable to high redshift galaxies. Due to its inclusion of very hot stars, it will be applicable to starburst objects both local and cosmological. This unique dataset, together with nearly six years of data from CoRoT, demonstrated that many stars in the galaxy do not have interiors like the Sun — even those only 20 to 30 percent more massive.

The low voices of giant stars confirmed predictions about the interior structures of red giants for the first time. Asteroseismology is also useful for measuring how the surface of a star rotates compared to its interior.

While studying stellar sound waves, scientists also were surprised to learn that in one type of red giant, the core rotates rapidly while the surface rotates slowly. A study using Kepler data found three giant stars whose interiors spin 10 times faster than their surfaces.

Many important aspects of a planet — including size, age and whether or not it could support life — can only be determined from what scientists know about its host star.

When a planet passes in front of its star, Kepler detects this "transit" by measuring a sharp dip in the brightness of the star as the planet blocks some of its light very different from the ripple-like quake signatures. Asteroseismology is a way to determine the mass. Stellar vibrations also help scientists determine how old a star is, which will affect the environment of its planets. A young star is more likely to have violent outbursts, and its planets may still be shuffling around in their orbits.

An older star has less frequent flare-ups, and its planets may be more stable. The more stars astronomers can examine through seismology, the better they can map where the young and old stars are, and understand which regions of the Milky Way formed first. This is the science of galactic archaeology.

By following the trails of vibrations in stars, like an interstellar Indiana Jones would, astronomers can reconstruct how our Milky Way formed. Some clusters contain very old stars, while others are far younger, providing astronomers with a laboratory for understanding stellar evolution. Stars spend most of their lives on the main sequence, where they fuse hydrogen into helium in their cores. When the available fuel is used up, they swell into giants and go through another cycle of evolution.

Astronomers track the way this works by studying the structure of the stars. In addition, aging stars can pulsate, changing their brightness in various ways. Some of these stars, known as Cepheid variables, fluctuate predictably enough to be used for measuring distances to nearby galaxies. Close binary stars can pull each other out of shape, strip matter from each other, or even merge into one star.

If the companion is a white dwarf, neutron star, or black hole, interactions can be even more dire for the star. When a star in the same mass range as the Sun dies, it sheds its outer layers, forming a planetary nebula. The elements from those outer layers enrich the surrounding environment, while the shape of the planetary nebula itself provides clues to the final days of the original star. High-mass stars explode as supernovas , which are energetic enough to fuse more elements and spread them through space.

Astronomers study supernovas and their remnants to understand the way these stars die and spread materials through the galaxy. The neutron stars and black holes they leave behind also shape their environments in profound ways. Artist's impressions of three types of supernovas from the explosion of extremely massive stars.

Such models help us understand why some observed supernovas produce powerful jets, while others do not. Support Our Science. Utility Menu News Events. Share this Page. Facebook Share on Facebook. Twitter Share on Twitter. Share on LinkedIn. Share via Email. Solar-Like Oscillations in Other Stars Observing aging stars as they shed huge amounts of material into surrounding space.

A one with 22 zeros behind it - a rough approximation of the number of stars in the observable universe. Big Questions. See All Staff. Related News. The Harvard Astronomical Glass Plate Collection is an archive of roughly , images of the sky preserved on glass photographic plates, the way professional astronomers often captured images in the era before the dominance of digital technology. The process can also lead to new discoveries in old images, particularly of events that change over time, such as variable stars, novas, or black hole flares.

Harvard and Smithsonian are both full institutional members of the latest epoch of the survey, SDSS-V, which started observations in Star formation is a complex process, beginning from cold clouds of gas and dust and ending with the diverse population of stars we observe in our galaxy and beyond.