Topic
Star hopping
About: Star hopping is a research topic. Over the lifetime, 3 publications have been published within this topic receiving 12 citations.
Papers
TL;DR: In this article, an adaptive optics observing method, called star-hopping, was proposed to search for a fifth planet at separations less than 10 au, interior to the four giant planets of the HR 8799 system.
Abstract: The direct imaging of extrasolar giant planets demands the highest possible contrasts (dH ~10 magnitudes) at the smallest angular separations (~0.1'') from the star. We present an adaptive optics observing method, called star-hopping, recently offered as standard queue observing for the SPHERE instrument at the VLT. The method uses reference difference imaging (RDI) but unlike earlier works, obtains images of a reference star for PSF subtraction, within minutes of observing the target star. We aim to significantly gain in contrast over the conventional angular differencing imaging (ADI) method, to search for a fifth planet at separations less than 10 au, interior to the four giant planets of the HR 8799 system. We obtained a total of 4.5 hours of simultaneous integral field spectroscopy (R~30, Y-H band with IFS) and dual-band imaging (K1 and K2-band with IRDIS) of the HR 8799 system and a reference star. The reference star was observed for ~1/3 of the total time, and should have dR~1 mag and separated on sky by ~1-2 deg. The star hops were made every 6-10 minutes, with only 1 minute gaps in on-sky integration per hop. We did not detect the hypothetical fifth planet at the most plausible separations, 7.5 and 9.7 au, down to mass limits of 3.6 MJup high signal-to-noise ratios. As noted in previous works, the planet spectra are matched very closely by some red field dwarfs. We also demonstrated that with star-hopping RDI, the contrast improvement at 0.1'' separation can be up to 2 magnitudes. Since ADI, meridian transit and the concomitant sky rotation are not needed, the time of observation can be chosen from within a 2-3 times larger window. In general, star-hopping can be used for stars fainter than R=4 magnitudes, since for these a reference star of suitable brightness and separation is usually available. The reduction software used in this paper has been made available online.
16 citations
1 Jan 2010
TL;DR: For example, Johnson et al. as mentioned in this paper measured the separation between double stars in arc seconds and the position angle in degrees that defined the orientation of pairs with respect to the celestial north.
Abstract: Professional astronomers have carried out visual double star measurements for over 200 years These scientists measured the separation between double stars in arc seconds and the position angle in degrees that defined the orientation of pairs with respect to celestial north There are two types of double stars: binary stars and optical doubles A binary star consists of two stars revolving around a common center of mass Over time, the orbital motion of each star can create an elliptical change in the observed separation and position angle if the pair proves to be binary in nature Conversely, if the two stars are an optical pair, meaning they do not orbit around a common center of mass, there will be a linear change in separation or position angle over timeToday’s astronomers continue to observe these changes with fairly simple equipment The typical setup for visual observations includes an equatorial mounted telescope with tracking motors, a laser etched astrometric eyepiece, and an inexpensive digital stopwatch that reads to the nearest 001 seconds Not only is this procedure used by professional astronomers but it can be performed accurately by amateur astronomers and students as well In fact, this type of research is particularly well suited for students for several reasons, including experience collecting and analyzing data, working as a team, and opportunity to promptly publish scientific papers (Johnson 2008) Figure 1 (next page) shows a student observing the double star Alberio
4 citations
Book•
28 Dec 2006
TL;DR: In this article, the ingredients of Nebulae are described, including star formation and composition, star formation, supernova reformation, and supernova supernova remnants, and star hopping.
Abstract: Introduction. PART 1- 1. Star Formation and Composition - the ingredients of Nebulae.- 2. The Milky Way - our Galaxy and Home to Nebulae - Emission Nebulae - Reflection Nebulae - Dark Nebulae - Planetary Nebulae - Supernova Remnants - Extragalactic nebulae? PART 2- 3. Instruments - naked eye, binoculars, RFT, Mak/SCT, Dobsonians.- 4. Techniques - Dark adapation, red light, averted vision.- 5. Accessories - eyepieces, filters, finders.- 6. Locating objects - setting circles, star hopping, 'goto'.- 7. Resources - finder charts, computer-based planetaria, deep-sky books, the Internet.- 8 Observing Guide - planning, conditions and weather, seeing and transparency, atmosphere, logging.- 9. Observing lists. Catalogues of nebulae - general: NGC/IC, Messier Gaseous: Lynds Planetaries: P+K, Strasbourg Dark: Barnard, Lynds
2 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 1 |
| 2010 | 1 |
| 2006 | 1 |