Tag: 泸州桑拿

Two giant planets detected around an evolved intermediatemass star

first_img Citation: Two giant planets detected around an evolved intermediate-mass star (2016, January 21) retrieved 18 August 2019 from https://phys.org/news/2016-01-giant-planets-evolved-intermediate-mass-star.html The planets were discovered by an international team of astronomers led by Bun’ei Sato of the Tokyo Institute of Technology. The researchers employed the Okayama Astrophysical Observatory (OAO) in Japan, the Xinglong Station in China and the Australian Astronomical Observatory (AAO) to observe HD 47366. The planets were detected by the radial velocity method, also known as Doppler spectroscopy, which uses gravity to detect exoworlds.The astronomers were searching for any signs of wobbling when observing HD 47366, as planets exert a gravitational tug when they orbit their parent stars, causing them to wobble back and forth. Three powerful spectrographs were needed to detect this wobbling: the HIgh Dispersion Echelle Spectrograph (HIDES) at OAO, the Coude Echelle Spectrograph (CES) at Xinglong and the University College London Echelle Spectrograph (UCLES) at AAO.Precise radial-velocity measurements using these spectrographs revealed the presence of two exoplanets orbiting HD 47366. By fitting a double Keplerian model to the obtained radial-velocity data, the researchers were able to determine the mass, semimajor axis and eccentricity of the newly discovered worlds. According to their computations, the inner and outer planet have minimum masses equal to 1.75 and 1.86 Jupiter masses, semimajor axes of 1.214 and 1.853 AU (astronomical units), and eccentricities of 0.089 and 0.278 respectively.With relatively small orbital separations, this planetary system has immediately become very intriguing for the scientists.”The planetary system is intriguing in the points that the best-fit Keplerian orbit is unstable, it is near but less likely in 2:1 mean-motion resonance, and could be stable if the orbits are nearly circular or in retrograde configuration,” the researchers wrote in the paper.To further investigate the orbital stability of the system and constrain orbital parameters, the astronomers performed dynamical analysis for the system. This analysis revealed that the best-fit orbits in prograde configuration are unstable. However, the scientists found that they are stable in the following cases: The two planets are in the 2:1 mean-motion resonance; the eccentricity of the outer planet is less than about 0.15; mutual inclination of two the planets is larger than 160 degrees.The researchers also assume that the current orbital configuration could also be caused by a possible third planet in this system. However, no convincing evidence supporting this theory has yet been released.According to the research team, it is still unknown why multi-giant-planet systems with small orbital separation are mostly found around evolved, intermediate-mass stars. The scientists have offered one possible explanation for this phenomenon.”It may be a primordial property of planets around intermediate-mass stars that could be an outcome of planet formation or an acquired one as a result of orbital evolution caused by stellar evolution (stellar tide and mass loss) of central stars,” the paper reads.To this date, precise radial-velocity surveys have found about 120 substellar companions around evolved stars. The discovery made by Sato and his team is another important finding increasing the population of multi-giant-planet systems found with relatively small orbital separations around evolved intermediate-mass stars. Planets around these type of stars, especially consisting of giant exoplanets, could be crucial for our understanding of formation and evolution of planetary systems. Explore further Monster planet is ‘dancing with the stars’ (Phys.org)—HD 47366 is an evolved star almost twice as massive as our sun. Located about 260 light years from the Earth, the star is approximately 1.6 billion years old, and, as it turns out, hosts two giant planets with a mass nearly two times that of Jupiter’s each. A research paper detailing the new findings was published online on Jan. 18 in the arXiv journal. More information: A Pair of Giant Planets around the Evolved Intermediate-Mass Star HD 47366: Multiple Circular Orbits or a Mutually Retrograde Configuration, arXiv:1601.04417 [astro-ph.EP] arxiv.org/pdf/1601.04417.pdfAbstractWe report the detection of a double planetary system around the evolved intermediate-mass star HD 47366 from precise radial-velocity measurements at Okayama Astrophysical Observatory, Xinglong Station, and Australian Astronomical Observatory. The star is a K1 giant with a mass of 1.81+-0.13M_sun, a radius of 7.30+-0.33R_sun, and solar metallicity. The planetary system is composed of two giant planets with minimum mass of 1.75^{+0.20}_{-0.17}Mjup and 1.86^{+0.16}_{-0.15}Mjup, orbital period of 363.3^{+2.5}_{-2.4} d and 684.7^{+5.0}_{-4.9} d, and eccentricity of 0.089^{+0.079}_{-0.060} and 0.278^{+0.067}_{-0.094}, respectively, which are derived by a double Keplerian orbital fit to the radial-velocity data. The system adds to the population of multi-giant-planet systems with relatively small orbital separations, which are preferentially found around evolved intermediate-mass stars. Dynamical stability analysis for the system revealed, however, that the best-fit orbits are unstable in the case of a prograde configuration. The system could be stable if the planets were in 2:1 mean-motion resonance, but this is less likely considering the observed period ratio and eccentricity. A present possible scenario for the system is that both of the planets have nearly circular orbits, namely the eccentricity of the outer planet is less than ~0.15, which is just within 1.4sigma of the best-fit value, or the planets are in a mutually retrograde configuration with a mutual orbital inclination larger than 160 degree. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Upper: Radial velocities of HD 47366 obtained with HIDES-S (red), HIDES-F (blue), CES-O (brown), CES-N (magenta), HRS (cyan), and AAT (green). The error bar for each point includes the extra Gaussian noise. The double Keplerian model for the radial velocities is shown by the solid line. Bottom: Residuals to the Keplerian fit. Credit: arXiv:1601.04417 [astro-ph.EP] © 2016 Phys.orglast_img read more

Top 15 attractions and things to do in Marrakech

first_img15. Visit EssaouiraMarrakech is fun but extremely hectic, so a day trip to the coastal town of Essaouira (pronounced ‘essa-weera’) can make for a welcome change of pace. This fortified walls of this fishing town are ideal for strolling along, and the market is measurably less frantic than that of Marrakech. The beach is also great for wandering, but better for windsurfing – the town is subject to strong winds that blow pretty much non-stop all year round. If you do go, make sure to stop by Gelateria Dolce Freddo on the main square for probably the best ice cream in Morocco. Supratours buses run between Marrakech and Essaouira – see their website for times. 10. Dar Si Said MuseumFurther your cultural education with a look at this museum of Moroccan handicrafts. Housed in another gorgeous nineteenth century palace, there are Berber trinkets, Moorish ceilings and Tuareg leatherwork to admire here. Look out for the wedding-reception chamber and elegant courtyards, originally built for the brother of Grand Vizier Bou Ahmed, Si Said. Opening times: Wed to Mon, 9am – 4.45pm.Location: Derb Si Said.Price: Adults Dhs10, Children Dhs3. 13. Take a trip into the desertFrom one day camel rides to four day epic treks to Fez, it’s worth exploring your surroundings even if you’re only on a short break in Marrakech. Er Chigaga Dunes in the Sahara desert are a popular choice, but most tours will include extra touches like a stay in an authentic Berber tent and home-cooked food around the campfire. Check out Top Desert for well-organised packages. Search flights to Marrakech ReturnOne wayMulti-cityFromAdd nearby airports ToAdd nearby airportsDepart14/08/2019Return21/08/2019Cabin Class & Travellers1 adult, EconomyDirect flights onlySearch flights Map Also known as Jemaa el-Fnaa, this famous square is the pivot around which the friendly chaos revolves and the ideal place to kickstart a city break in Marrakech. During the blazing heat of the day, scurry to one of the covered rooftop cafes that surround the square, providing an ideal viewing spot for the madness below. Stall holders loudly proclaim their wares, snake charmers do their thing, tourists look bewildered and the loudspeakers of the nearby Koutoubia Mosque deafen with the call to prayer five times a day. But it’s after dark when the square really comes alive – an army of food stalls invades, and locals and tourists alike descend in the blessed cool of the evening to enjoy local cuisine at rock-bottom prices. Pick a stall, park yourself on a chair and enjoy. 11. Madrassa Ben YoussefA former religious school dating back to the fourteenth century, the building’s exterior belies the startling green and terracotta mosaics, domed prayer hall and intricate stucco-work. You can still see the hundreds of tiny dormitory ‘cells’ for the students. Local guides can bring the surroundings to life for a few dirhams. The Almoravid sultan Ben Youssef also lent his name to the oldest mosque in Marrakech, nearby, although you’ll have to admire it from the outside if you’re non-Muslim.Opening times: Sun to Sat 8am – 5pm.Location: Kaat Benahid.Price: 20Dhs. 9. Marrakech MuseumPeer at ancient Islamic coins, bright patterned ceramics and jewelled weaponry fit for the Sultans of old, in this treasure house of Moroccan artefacts. Add to this the stunner of a building – a former ministerial palace – resplendent with tiled floors, chandeliers and stained glass, and this is definitely worth a stop on your tour of Marrakech sights.Opening times: Daily 9am – 6.30pm.Location: Place Ben Youssef, Marrakech Medina.Price: 30Dhs. How to get to MarrakechRyanair, easyJet and BA all fly direct to Marrakech from London. If you’re flying from regional UK airports like Birmingham or Manchester, you can change at European airports like Amsterdam or Lisbon. Marrakech Menara Airport is less than 20 minutes’ (8km) drive from the centre of Marrakech.Find the cheapest deals on flights to Marrakech with Skyscanner: 14. Feast at Al FassiaBeloved by Moroccans as much as visitors, Al Faissa is where to go for upmarket, but authentic local cuisine. With two locations (Al Fassia Aguedal is in a boutique hotel south of central Marrakech), it also has the fairly unusual set-up of being run almost entirely by women. Though their pigeon bstilla (pigeon pie) and roasted shoulder of lamb dishes are of the highest quality, dinner for two will only set you back around £40.Opening times: Lunch and dinner every day except Tuesdays.Location: (Al Faissa Gueliz, Marrakech city centre) 55, Boulevard Zerktouni.Price: Mains from 130Dhs (around £10). 1. Watch the madness unfold at Djemma el-Fna ReturnOne wayMulti-cityFromAdd nearby airports ToAdd nearby airportsDepartReturnCabin Class & Travellers1 adult, EconomyDirect flights onlySearch flights Mapcenter_img 8. Make time for teaMoroccan mint tea is a staple of daily life in Marrakech. People drink it everywhere and at any time of day, and you’ll inevitably be offered it at some point. It’s considered impolite to refuse, so it’s just as well that the hot tea is invariably delicious and surprisingly cooling too. It’s made from a mixture of green tea and fresh mint leaves along with lashings and lashings of sugar – if you’re used to mint tea au naturel then you may find the sweet, pungent taste quite surprising. Dar Belkabir just off the Djemma El-Fna offers a mean cuppa, but you can find a decent mint tea pretty much anywhere. 6. Take a turn around Koutoubia MosqueThe 77-metre-tall minaret of this sizable mosque, located right next to Djemma El-Fna, is a handy marker for those at sea in the souk. A closer inspection is warranted, however, if only to appreciate the ornate ceramics and scalloped arches of this impressive 12th-century building. Non-Muslims are not permitted to go inside, but the gardens are open from 8 am to 8 pm and offer the perfect place for an early evening wander. 3. Scrub up in a hammamAfter pounding the dusty streets all day giving the sights a thorough see, there’s nothing better than a long hot scrub in a hammam (steam room). After soaking in the steam, you’ll be lathered up with ghassoul (black soap made from natural mineral clay) and then scrubbed down thoroughly with a kessa (a sort of rough glove) – the layers of skin will peel off alarmingly, but I guarantee it’s the cleanest you’ll ever feel in your life. For a taste of luxury, try Les Bains de Marrakech or for a – potentially more fun – local option in which you’ll be surrounded by the everyday gossip of the men and women (segregated, of course) who visit the hammam every week. Hammam Dar El Bacha is a popular choice – men go in the morning, women in the afternoon and evening. Where to stay in MarrakechIf you don’t want to splash out some £800 on a stay at the Royal Mansour Marrakech, a certain level of comfort is still attainable IN Marrakech. For a more reasonable £127 Villa Makassar comes well-equipped with a library, a hot tub and rooftop terrace and is handy for the Medina and big Marrakech attractions like the Royal Palace.For bargain rates, try Kaktus Hostel, south-west of the centre. Laid out around a courtyard like a basic riad, it has a good eco-conscious approach and creative atmosphere.Find hotels in Marrakech*Published March 2017. Any prices are lowest estimated prices only at the time of publication and are subject to change and/or availability.**Still looking for inspiration? We’ve got some alternative city break ideas for you below:Top 10 things to do in PalermoPalermo provides an exotic mix of African and European culture – and a grisly reminder of the past lurks beneath.Discover Belgrade: top things to see and doFrom cutting edge street art to brutalist Yugoslav-era architecture, here are the best things to see and do in the beautiful Serbian capital, Belgrade.The best things to do in PortoFramed by the sea and the mighty River Duoro, Portugal’s second city is home to one of the most beautiful old towns in Europe, a swathe of historic churches, gardens and (naturally) port wine. Skyscanner is the world’s travel search engine, helping your money go further on flights, hotels and car hire. 2. Cosy up in a riadThere are hundreds of riads to choose from in Marrakech, and they can provide an oasis of calm and hospitality away from the hectic streets. The name ‘riad’ derives from the Arabic for garden, and these guesthouses tend to be arranged around a picturesque open courtyard that’s usually festooned with plants. They often boast roof terraces too, which are perfect for relaxing in the shade with a good book. The only down side is that riads can be so cosy that it’s hard to lever yourself out of them to go sightseeing. A couple of recommendations are Riad Les Yeux Bleus, which is situated around two central courtyards and has been beautifully restored by the French owners, and Riad Chafia, the local owners of which are very helpful and will be happy to welcome you with a cup of mint tea. 4. Wonder at the Palais de la BahiaConstruction of this grand palace began in 1866 at the behest of Grand Vizier Si Moussa, a former slave who rose to become the sultan’s right-hand man. After his death the palace was expanded considerably by his son Bou Ahmed, who also became grand vizier. The rambling, one-storey building is full of constant surprises, as intimate gardens can be found right next to grand colonnaded courtyards, which in turn give way to private apartments laden with astonishingly detailed stuccos. The word ‘bahia’ means ‘beauty’ or ‘brilliance’, and it’s certainly a fitting name.Opening times: Mon to Sun 8am – 5pm.Location: 52, Jemaa El Fna.Price: 10Dhs. 7. Relax in Jardin MajorelleIf you’re maxed out on mosques and saturated with souks, the Jardin Majorelle is the place to come for something a bit different. This tranquil garden with its calming blue buildings was laid out by the French artist Jacques Majorelle in the 1920s and 1930s, and in 1980 it was bought by clothes designer Yves Saint-Laurent and his business partner Pierre Bergé. After Saint-Laurent’s death in 2008, his ashes were scattered in the garden. The shaded fountains offer a soothing escape from the city’s heat, and the small gallery of Majorelle’s paintings is worth a look.Opening times: (Oct 1 to Apr 30) 8am – 5:30pm, (May 1 to Sept 30) 8am – 6pm.Location: Rue Yves Saint Laurent.Price: (Garden) 70Dhs; (Museum) 30Dhs. 12. Peek at the Saadian TombsBuilt by Sultan al-Ghalib Abdullah in 1557, this mausoleum is the final resting place of the sixteenth and seventeenth century Saadian dynasty, walled up and kept hidden by subsequent rulers and only rediscovered in 1917. Works of art in marble and mosaic, you might need to come early to miss the crowds queuing up to see the magnificent main tomb, dedicated to Lalla Mas’ouda, mother of Sultan Ahmed al-Mansour ed-Dahbi.Opening times: Daily 9am – 4.45pm.Location: Rue de la Kasbah, accessed through the Kasbah Mosque.Price: Adults Dhs10, Children Dhs3. 5. Explore the souks of the MedinaThe twisting medieval passageways of the Marrakech souks (markets) within the medina (old town) can be intimidating, but the best approach is to just plunge in. You’ll almost certainly get lost, even with the help of a map, so just follow your feet, enjoy the sights and smells of the market stalls and see where you end up – you’ll pop out on a main street eventually. There’s not really one but five souks to peruse, including the pungent Spice Souk, and the charming Slipper Souk. Local people may offer to guide you to various sights within the souk, but be aware that you’re just as likely to end up at their brother’s carpet shop as the historical Ben Youssef Madrasa. If that does happen, there’s little to do but shrug, laugh and start haggling. RelatedWhere to go on holiday in OctoberHalloween is around the corner, the last leaves are tenaciously clinging to the branches and the coffee shops are whipping out the pumpkin spice syrup. Summer might be over, but that doesn’t mean the holidays need to be. Check out the Skyscanner guide to the best cities, beaches, and events…Last chance city sun: 6 flights for £60 or lessLast chance city sun: 6 flights for £60 or lessTop 15 attractions and things to do in ThessalonikiVenerable in age and young at heart, Greece’s second city rewards those who follow their noses into bakeries and hidden backstreets, or wander through secret doorways and down into crypts. Uncover the best of Thessaloniki on a weekend away, with our guide to the top things to see, do and…last_img read more