Near-infrared Spectroscopy of Low Mass Stars and Brown Dwarfs PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Near-infrared Spectroscopy of Low Mass Stars and Brown Dwarfs PDF full book. Access full book title Near-infrared Spectroscopy of Low Mass Stars and Brown Dwarfs by John Christian Wilson. Download full books in PDF and EPUB format.
Author: John Christian Wilson
Publisher:
ISBN:
Category :
Languages : en
Pages : 278
Get Book Here
Book Description
Author: John Christian Wilson
Publisher:
ISBN:
Category :
Languages : en
Pages : 278
Get Book Here
Book Description
Author: Gregory Nathan Mace
Publisher:
ISBN:
Category :
Languages : en
Pages : 323
Get Book Here
Book Description
The mass of a star at formation determines its subsequent evolution and demise. Low-mass stars are the most common products of star formation and their long main-sequence lifetimes cause them to accumulate over time. Star formation also produces many substellar-mass objects known as brown dwarfs, which emerge from their natal molecular clouds and continually cool as they age, pervading the Milky Way. Low-mass stars and brown dwarfs exhibit a wide range of physical characteristics and their abundance make them ideal subjects for testing formation and evolution models. I have examined a pair of pre-main sequence spectroscopic binaries and used radial velocity variations to determine orbital solutions and mass ratios. Additionally, I have employed synthetic spectra to estimate their effective temperatures and place them on theoretical Hertzsprung-Russell diagrams. From this analysis I discuss the formation and evolution of young binary systems and place bounds on absolute masses and radii. I have also studied the late-type T dwarfs revealed by the Wide-field Infrared Survey Explorer (WISE). This includes the exemplar T8 subdwarf Wolf 1130C, which has the lowest inferred metallicity in the literature and spectroscopic traits consistent with old age. Comparison to synthetic spectra implies that the dispersion in near-infrared colors of late-type T dwarfs is a result of age and/or thin sulfide clouds. With the updated census of the L, T, and Y dwarfs we can now study specific brown dwarf subpopulations. Finally, I present a number of future studies that would develop our understanding of the physical qualities of T dwarf color outliers and disentangle the tracers of age and atmospheric properties.
Author: Rafael Rebolo
Publisher: Cambridge University Press
ISBN: 9780521663359
Category : Science
Languages : en
Pages : 284
Get Book Here
Book Description
This volume provides a state-of-the-art review of our current knowledge of brown dwarfs and very low-mass stars. The hunt for and study of these elusive objects is currently one of the most dynamic areas of research in astronomy for two reasons. Brown dwarfs bridge the gap between stars and planets, and they may constitute an important part of the 'dark matter' of the Universe. This volume presents review articles from a team of international authorities who gathered at a conference in La Palma to assess the spectacular progress that has been made in this field in the last few years.
Author: Caleb Cañas
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Get Book Here
Book Description
In this dissertation, I present a comprehensive overview of near-infrared spectroscopy and spaced-based photometric and astrometric surveys as fundamental tools for the validation and characterization of Jupiter-sized planets and brown dwarfs orbiting main sequence stars. I begin by discussing my involvement in a spectroscopic survey of planetary candidates from Kepler that leverages the efficiency and multiplexing capabilities of the northern Apache Point Observatory Galactic Evolution Experiment (APOGEE-N) spectrograph. While APOGEE-N achieves a radial velocity precision of ~100 m/s, it has facilitated a multi-visit survey of >1600 different stars. This, coupled with its near-infrared wavelength coverage, make APOGEE-N an ideal instrument to follow-up Kepler planet candidates that are expensive observations for traditional high-precision optical instruments. This program was designed to investigate a large fraction of the planetary candidates identified in Kepler and characterize the false positive scenarios that can mimic the signal of a genuine planet. I summarize the pipeline developed to reduce APOGEE-N spectra and derive radial velocities and characterize a subset of 28 low-mass companions using the public data release from this survey. I also highlight the ability of near infrared spectrometers, such as APOGEE-N, to aid in the vetting and validation of planetary systems too faint for extensive observations with single-object optical spectrographs. I then discuss my work characterizing Jupiter-sized companions to M dwarfs discovered by NASA's TESS mission using two high-precision, high-resolution spectrographs: the Habitable-zone Planet Finder (HPF) and NEID. I summarize the framework developed to vet and confirm these systems with a combination of RVs, photometry, high-contrast imaging, and astrometric measurements from Gaia. I highlight four systems discovered with TESS: (i) TOI-1899, the first M dwarf system known to have a transiting Jupiter at a period >10 days and a lucrative target for future atmospheric characterization for a temperate gas giant, (ii) TOI-3714, an M2 dwarf system with a transiting hot Jupiter and a distant white dwarf companion, (iii) TOI-3629, an M1 dwarf system hosting a transiting hot Jupiter, and (iv) TOI-2119, an M2 dwarf with a brown dwarf companion on an eccentric orbit that is an ideal target for a measurement of the projected spin-orbit misalignment with the host star. I demonstrate that the near-infrared and extended red optical wavelength coverage of HPF and NEID, respectively, enable precise mass measurements for Jupiter-sized planets and brown dwarfs orbiting M dwarfs. Lastly, I present a discussion of the changes to come with data from two all-sky surveys, TESS and Gaia, that will revolution the discovery of large companions to M dwarfs and the synergy of these discoveries with red sensitive spectrometers to enable an ensemble of well-characterized planets and brown dwarfs that are amenable to population studies and demographic analysis to constrain their origin channels.
Author: Iain A. Steele
Publisher:
ISBN:
Category : Brown dwarf stars
Languages : en
Pages :
Get Book Here
Book Description
Author: Hugh R.A. Jones
Publisher: Springer Science & Business Media
ISBN: 3642566723
Category : Science
Languages : en
Pages : 199
Get Book Here
Book Description
Once you have looked at the night sky on a moonless night it is not hard to realise why so much of our science and religion has its roots in the stars. Yet it took until 1850 to realise that fainter stars were not necessarily further away, nor the brighter ones closer. In fact within the magnitude range observable to the naked eye it is probable that the brighter star is in fact further away. Even today the measurement of stellar distances is relatively difficult and is gener ally only done using dedicated telescopes. In the early years of the 20th century Hertzsprung and Russell developed a powerful classification diagram which al lows stars to be distinguished using a plot of their colour versus magnitude. The construction of this diagram involved the use of spectroscopy which has become the cornerstone of modern astronomy. As telescopes become more powerful, de tectors more sensitive and more physics is added to astrophysics, astronomical spectroscopy becomes a more powerful tool. The concern of this book is the spectral classification of stars. With a single spectrum of a star it is possible to uniquely classify an object and find its place on the Hertzsprung-Russell diagram. This spectrum is thus equivalent to having the colour and the magnitude of the object which can in turn be related to mass and other quantities.
Author: Viki Joergens
Publisher: Springer Science & Business Media
ISBN: 3319011626
Category : Science
Languages : en
Pages : 174
Get Book Here
Book Description
The years 2012/2013 mark the 50th anniversary of the theoretical prediction that Brown Dwarfs, i.e. degenerate objects which are just not massive enough to sustain stable hydrogen fusion, exist. Some 20 years after their discovery, how Brown Dwarfs form is still one of the main open questions in the theory of star formation. In this volume, the pioneers of Brown Dwarf research review the history of the theoretical prediction and the subsequent discovery of Brown Dwarfs. After an introduction, written by Viki Joergens, reviewing Shiv Kumar's theoretical prediction of the existence of brown dwarfs, Takenori Nakano reviews his and Hayashi's calculation of the Hydrogen Burning Minimum Mass. Both predictions happened in the early 1960s. Jill Tarter then writes on the introduction of the term 'Brown Dwarf', before Ben Oppenheimer, Rafael Rebolo and Gibor Basri describe their first discovery of Brown Dwarfs in the 1990s. Lastly, Michael Cushing and Isabelle Baraffe describe the development of the field to the current state of the art. While the book is mainly aimed at the Brown Dwarf research community, the description of the pioneering period in a scientific field will attract general readers interested in astronomy as well.
Author: Kimberly Dolan Ward-Duong
Publisher:
ISBN:
Category : Brown dwarf stars
Languages : en
Pages : 0
Get Book Here
Book Description
The lowest-mass stars, known as M-dwarfs, form target samples for upcoming exoplanet searches, and together with lower-mass substellar objects known as brown dwarfs, are among prime targets for detailed study with high-contrast adaptive optics (AO) imaging and sub-millimeter interferometry. In this thesis, I describe results from three studies investigating the companion properties and environments of low-mass systems: (1) The 245-star M-dwarfs in Multiples (MinMs) Survey, a volume-limited survey of field M-dwarf companions within 15 pc, (2) the Taurus Boundary of Stellar/Substellar (TBOSS) Survey, an ongoing study of disk properties for low-mass members within the Taurus star-forming region, and (3) spectroscopy of a brown dwarf companion using the Gemini Planet Imager (GPI). Direct imaging of M-dwarfs is a sensitive technique to identify low-mass companions over a wide range of orbital separation, and the high proper motion of nearby M-dwarfs eases confirmation of new multiple stars. Combining AO and wide-field imaging, the MinMs Survey provides new measurements of the companion star fraction (CSF), separation distribution, and mass ratio distribution for the nearest K7-M6 dwarfs. These results demonstrate the closer orbital separations (~6 AU) and lower frequency (~23% CSF) of M-dwarf binaries relative to higher-mass stars. From the TBOSS project, I report 885μm Atacama Large Millimeter/sub-millimeter Array continuum measurements for 24 Taurus members spanning the stellar/substellar boundary (M4-M7.75). Observations of submillimeter emission from dust grains around the lowest-mass hosts show decreasing disk dust mass for decreasing host star mass, consistent with low frequencies of giant planets around M-dwarfs. Compared to the older stellar association of Upper Scorpius, Taurus disks have a factor of four higher mass in submillimeter-sized grains. From the GPI Exoplanet Survey, I describe near-infrared spectroscopy of an unusually red companion orbiting inside the debris disk of an F5V star. As the second brown dwarf discovered within the innermost region of a debris disk, the properties of this system offer important dynamical constraints for companion-disk interaction and a useful benchmark for brown dwarf and giant planet atmospheric study.
Author: Jonathan Tottle
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Author: Gregory Ronald Schultz
Publisher:
ISBN:
Category :
Languages : en
Pages : 280
Get Book Here
Book Description
