Arnold Leitner Ph D Popular Books

Arnold Leitner Ph D Biography & Facts

Proxima Centauri is a small, low-mass star located 4.2465 light-years (1.3020 pc) away from the Sun in the southern constellation of Centaurus. Its Latin name means the 'nearest [star] of Centaurus'. It was discovered in 1915 by Robert Innes and is the nearest-known star to the Sun. With a quiescent apparent magnitude of 11.13, it is too faint to be seen with the unaided eye. Proxima Centauri is a member of the Alpha Centauri star system, being identified as component Alpha Centauri C, and is 2.18° to the southwest of the Alpha Centauri AB pair. It is currently 12,950 AU (0.2 ly) from AB, which it orbits with a period of about 550,000 years. Proxima Centauri is a red dwarf star with a mass about 12.5% of the Sun's mass (M☉), and average density about 33 times that of the Sun. Because of Proxima Centauri's proximity to Earth, its angular diameter can be measured directly. Its actual diameter is about one-seventh (14%) the diameter of the Sun. Although it has a very low average luminosity, Proxima Centauri is a flare star that randomly undergoes dramatic increases in brightness because of magnetic activity. The star's magnetic field is created by convection throughout the stellar body, and the resulting flare activity generates a total X-ray emission similar to that produced by the Sun. The internal mixing of its fuel by convection through its core, and Proxima's relatively low energy-production rate, mean that it will be a main-sequence star for another four trillion years. Proxima Centauri has two known exoplanets and one candidate exoplanet: Proxima Centauri b, Proxima Centauri d and the disputed Proxima Centauri c. Proxima Centauri b orbits the star at a distance of roughly 0.05 AU (7.5 million km) with an orbital period of approximately 11.2 Earth days. Its estimated mass is at least 1.07 times that of Earth. Proxima b orbits within Proxima Centauri's habitable zone—the range where temperatures are right for liquid water to exist on its surface—but, because Proxima Centauri is a red dwarf and a flare star, the planet's habitability is highly uncertain. A candidate super-Earth, Proxima Centauri c, roughly 1.5 AU (220 million km) away from Proxima Centauri, orbits it every 1,900 d (5.2 yr). A sub-Earth, Proxima Centauri d, roughly 0.029 AU (4.3 million km) away, orbits it every 5.1 days. General characteristics Proxima Centauri is a red dwarf, because it belongs to the main sequence on the Hertzsprung–Russell diagram and is of spectral class M5.5. The M5.5 class means that it falls in the low-mass end of M-type dwarf stars, with its hue shifted toward red-yellow by an effective temperature of ~3,000 K. Its absolute visual magnitude, or its visual magnitude as viewed from a distance of 10 parsecs (33 ly), is 15.5. Its total luminosity over all wavelengths is only 0.16% that of the Sun, although when observed in the wavelengths of visible light the eye is most sensitive to, it is only 0.0056% as luminous as the Sun. More than 85% of its radiated power is at infrared wavelengths.In 2002, optical interferometry with the Very Large Telescope (VLTI) found that the angular diameter of Proxima Centauri is 1.02±0.08 mas. Because its distance is known, the actual diameter of Proxima Centauri can be calculated to be about 1/7 that of the Sun, or 1.5 times that of Jupiter. The star's mass, estimated from stellar theory, is 12.2% M☉, or 129 Jupiter masses (MJ). The mass has been calculated directly, although with less precision, from observations of microlensing events to be 0.150+0.062−0.051 M☉.Lower mass main-sequence stars have higher mean density than higher mass ones, and Proxima Centauri is no exception: it has a mean density of 47.1×103 kg/m3 (47.1 g/cm3), compared with the Sun's mean density of 1.411×103 kg/m3 (1.411 g/cm3). The measured surface gravity of Proxima Centauri, given as the base-10 logarithm of the acceleration in units of cgs, is 5.20. This is 162 times the surface gravity on Earth.A 1998 study of photometric variations indicates that Proxima Centauri completes a full rotation once every 83.5 days. A subsequent time series analysis of chromospheric indicators in 2002 suggests a longer rotation period of 116.6±0.7 days. Later observations of the star's magnetic field subsequently revealed that the star rotates with a period of 89.8±4 days, consistent with a measurement of 92.1+4.2−3.5 days from radial velocity observations. Structure and fusion Because of its low mass, the interior of the star is completely convective, causing energy to be transferred to the exterior by the physical movement of plasma rather than through radiative processes. This convection means that the helium ash left over from the thermonuclear fusion of hydrogen does not accumulate at the core but is instead circulated throughout the star. Unlike the Sun, which will only burn through about 10% of its total hydrogen supply before leaving the main sequence, Proxima Centauri will consume nearly all of its fuel before the fusion of hydrogen comes to an end.Convection is associated with the generation and persistence of a magnetic field. The magnetic energy from this field is released at the surface through stellar flares that briefly (as short as per ten seconds) increase the overall luminosity of the star. On May 6, 2019, a flare event bordering Solar M and X flare class, briefly became the brightest ever detected, with a far ultraviolet emission of 2×1030 erg. These flares can grow as large as the star and reach temperatures measured as high as 27 million K—hot enough to radiate X-rays. Proxima Centauri's quiescent X-ray luminosity, approximately (4–16) × 1026 erg/s ((4–16) × 1019 W), is roughly equal to that of the much larger Sun. The peak X-ray luminosity of the largest flares can reach 1028 erg/s (1021 W).Proxima Centauri's chromosphere is active, and its spectrum displays a strong emission line of singly ionized magnesium at a wavelength of 280 nm. About 88% of the surface of Proxima Centauri may be active, a percentage that is much higher than that of the Sun even at the peak of the solar cycle. Even during quiescent periods with few or no flares, this activity increases the corona temperature of Proxima Centauri to 3.5 million K, compared to the 2 million K of the Sun's corona, and its total X-ray emission is comparable to the sun's. Proxima Centauri's overall activity level is considered low compared to other red dwarfs, which is consistent with the star's estimated age of 4.85 × 109 years, since the activity level of a red dwarf is expected to steadily wane over billions of years as its stellar rotation rate decreases. The activity level appears to vary with a period of roughly 442 days, which is shorter than the solar cycle of 11 years.Proxima Centauri has a relatively weak stellar wind, no more than 20% of the mass loss rate of the solar wind. Because the star is much smaller than the Sun, the mass loss per unit surface area from Proxima Centauri may be eight times that f.... Discover the Arnold Leitner Ph D popular books. 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  • Dracula synopsis, comments

    Dracula

    Bram Stoker

    An Apple Books Classic edition. Few characters have seized readers’ imaginations quite like Count Dracula of Transylvania, the hero of Bram Stoker’s classic. The 1897 novel put vam...

  • The Next Girl synopsis, comments

    The Next Girl

    Carla Kovach

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  • The Holy Bible - King James Version synopsis, comments

    The Holy Bible - King James Version

    King James

    Holy Bible King James Version Few Sample Paragraphs from The Holy Bible eBook, Genesis (OT) 1 Gen. 1 IN the beginning God created the heaven and the earth. 2 And the earth was with...

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    Inception of Gold

    Lexy Timms

    Things are not as bad as they seem. They are worse. Being the personal assistant to a narcissistic actress who just happens to own the key to my family's undoing isn't ex...

  • Once Upon A One-Night Stand synopsis, comments

    Once Upon A One-Night Stand

    Zoey Locke

    At first sight, there was electrifying chemistry.  So why not go for it? After all, Lynx Grove, the city's most eligible bachelor, wants to claim her, at least for th...

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    A Green Kind of Witch

    Sierra Cross

    Cinderella crossed with Mean Girls.   That's what Hazel's daily existence feels like. Born to a family of elegant yet shallow Beige Witches, seventeen y...

  • Salvation synopsis, comments

    Salvation

    Meghan O'Flynn

    If you like mouthy detectives, serial killers, and suspenseful mysteries that don't quit, this chilling and actionpacked hardboiled detective series has you covered! Try this ...

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    Coffee Girl

    Sophie Sinclair

    Mackenzie "Kiki" Forbes finds herself in a pickle. Either become her snarky sister's nanny, or move halfway across the country to work as assistanttothestylist of a ...

  • A Bookshop to Die For synopsis, comments

    A Bookshop to Die For

    M.P. Black

    Ditching her fiancé at the altar, Alice Hartford bolts to her childhood hometown to reconnect with the last, happy remnant of her past: her mom's old bookstore. But the bookst...

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    My Paper Heart

    Magan Vernon

    One piece of paper can change everything After my parents received the letter I failed out of college, they didn't ask questions. They just sent me to work for my great aunt i...

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    Silenced Girls

    Roger Stelljes

    “ Wow wow wow!  Grips you in a choke hold and  does not let go … Oozes suspense and  bonechilling twists and turns .  Astonishing … One of those...

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    The Great Gatsby

    F. Scott Fitzgerald

    An Apple Books Classics edition. The Roaring Twenties are in full effect in F. Scott Fitzgerald’s riveting classic. Manabouttown Jay Gatsby seems to have it all, including loads of...

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    All Fired Up

    Kathryn Shay

    Captain Jarek Zenko, a war veteran and firefighter, meets Lacey Roth at a bar one night. They don’t share their real identities, even when they retreat to a hotel. When they meet t...

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    The Scarlet Letter

    Nathaniel Hawthorne

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    Caught Up with the Captain

    Kait Nolan

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  • Pride and Prejudice synopsis, comments

    Pride and Prejudice

    Jane Austen

    An Apple Books Classic edition. Jane Austen’s beloved classic opens with this witty and very memorable line: “It is a truth universally acknowledged, that a single man in possessio...

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    The Target

    Lexy Timms

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    Escape, A New Life

    David J Antocci

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    How to Choose a Guy in 10 Days

    Lila Monroe

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  • Pretty Little Lies synopsis, comments

    Pretty Little Lies

    Ivy Thorn

    Four years ago, Nicolo Marchetti took my innocence. But he left me with something else Nicolo almost took everything from me. My virginity, my reputation, and very nearly my future...

  • The Adventures of Sherlock Holmes synopsis, comments

    The Adventures of Sherlock Holmes

    Arthur Conan Doyle

    An Apple Books Classic You get not one, not two, but 25 gripping mysteries in Arthur Conan Doyle’s first of five collections of Sherlock Holmes short stories. Follow the brilliant ...

  • Meditations synopsis, comments

    Meditations

    Emperor of Rome Marcus Aurelius

    Meditations is a series of personal writings by Marcus Aurelius, Roman Emperor 161–180 CE, setting forth his ideas on Stoic philosophy.

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    Silver Santa

    Lacey Silks

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    Teach Me

    Cassandra Dean

    From awardwinning author Cassandra Dean comes a tale where lessons of pleasure between a curious, sunshine widow and a dissolute, grumpy earl leads to passion and allconsuming love...

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    The Odyssey

    Homer

    An Apple Books Classic edition. Homer’s eighthcentury epic poem is a companion to The Iliad . It tells the story of Odysseus, who journeys by ship for 10 years after the Trojan War...

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    The Cupcake Cottage

    Jean Oram

    NHL player Maverick Blades could fall in love with anyone... But he had to fall for a woman who falls under the Bro Code as untouchablehis best friend’s beautiful ex, DaisyMae Ray....

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    Enemies With Benefits

    Roxie Noir

    I don’t love him. I don’t even like him. I just want him. Eli Loveless was my nemesis from the first day of kindergarten until we graduated high school. Everything I did, he had to...

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    Becoming Lady Dalton

    Carrie Lomax

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    Whiskey Girl

    Melissa Belle

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  • Law of Attraction synopsis, comments

    Law of Attraction

    Jordan Hollis

    How to Finally Overcome the Hurdles of Manifesting Proven, effective and enjoyable ways to help you manifest faster… Right now, think of something that makes you successful. If you...

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    Noxious

    Lexy Timms

    Stop setting yourself on fire to keep someone else warm. Brady and Levi have been together since high school, since before he became famous and started thinking only about himself....

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    Masters of Restraint

    Ines Johnson

    My new boss is good at giving orders. But his latest demand is NSFW. Especially when his two business partners want in on our deal. My new boss My boss’s boss Their investor &#...

  • Tempting the King synopsis, comments

    Tempting the King

    Jessa York

    An escaped Mafia Queen, hiding from her past. A Mafia King who wants to claim her… Giselle They think I'm lostbut I know better. I can never be found. The path I've creat...

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    The Wonderful Wizard of Oz

    L. Frank Baum

    An Apple Books Classic edition. You’ve seen the iconic 1939 movie, but do you know about the talking field mice, the Winkies, and the Witch of the North that appear in the original...

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    Man In The Water

    Jon Hill

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    Hot Off the Press

    Lexy Timms

    "This is what really happened… reported by a free press, for a free people…" Wes Shaw leads a secret double life. As the secret owner of a billion dollar newspap...

  • The Stoic Mind synopsis, comments

    The Stoic Mind

    Addy Osmani & GoLimitlesss

    Discover the timeless wisdom of Stoicism in a modern context with "The Stoic Mind," an enlightening visual guide by Addy Osmani and GoLimitlesss. This rich exploration co...

  • Good Guy synopsis, comments

    Good Guy

    Kate Meader

    He's a Special Forces veteran making his pro hockey debut. She's a dogged sports reporter determined to get a scoop. She's also his best friend's widow . . . Fa...

  • The Seduction Series Boxset synopsis, comments

    The Seduction Series Boxset

    Roxy Sloane

    “Sensual, thrilling and wild!”   Discover the bestselling series in one collection: THE SEDUCTION, THE BARGAIN, and THE INVITATION. Perfect for fans of Ana Huang, Sierra S...

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    Hard Love

    Peyton Banks

    He was football royalty. Legendary quarterback. A champion.  Reiner Strickland had led his team to three national championships and playing a knight in shining armor was a...

  • Dream Psychology synopsis, comments

    Dream Psychology

    Sigmund Freud

    An Apple Books Classic edition. Written by the founding father of psychoanalysis, Sigmund Freud’s 1899 book is the definitive text on learning to interpret dreams. Freud’s groundbr...

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    Finding Cinderella

    Colleen Hoover

    #1 New York Times bestselling author of It Starts with Us and It Ends With Us writes a free novella about the search for happily ever after. A chance encounter in the dark leads ei...

  • His Own Heaven synopsis, comments

    His Own Heaven

    Jennie Kew

    Winner of the 2021 Passionate Plume Award for BDSM Romance Finalist in the 2021 Stiletto Contest for Contemporary Romance He taught her to trust, she taught him to love. ​ Lucy Bar...

  • Just Me synopsis, comments

    Just Me

    Lexy Timms

    We all need somewhere where we feel safe… After leaving her abusive husband, Katherine Marshall is out on her own for the first time. She's hopped from city to city to avoid t...

  • Eternal synopsis, comments

    Eternal

    W.J. May

    She will fight for what is hers. When the king is murdered, Katerina, his only daughter, must flee for her life. She finds herself on a strange and dangerous path. Alone for the fi...

  • School of Potential synopsis, comments

    School of Potential

    W.J. May

    USA Today Bestselling author, W.J. May brings you a continuation of the international bestselling series, The Chronicles of Kerrigan! Come back and enjoy the famous characters, or ...

  • Awaken Me synopsis, comments

    Awaken Me

    Jenna Jacob

    He was more than a ghost haunting my dreams…he was real. By day, I’m Julianna Garrett …a prim, proper accountant. By night, I’m tormented by dreams of an alpha, ambereyed Adonis wh...

  • Christmas in Sweetbriar Cove synopsis, comments

    Christmas in Sweetbriar Cove

    Melody Grace

    Celebrate the holidays in Sweetbriar Cove with this festive romance collection, containing two sizzling smalltown holiday stories perfect for fans of Tessa Bailey, Sophie Kinsella...

  • Alpha synopsis, comments

    Alpha

    Sybil Bartel

    Billionaire. Mercenary. Navy SEAL. The Teams trained me to be a killer. War taught me to be ruthless. Then an illfated mission proved I was human. Combat wounded, cut loose by the ...

  • The Four Loves synopsis, comments

    The Four Loves

    C. S. Lewis

    The Four Loves summarizes four kinds of human loveaffection, friendship, erotic love, and the love of God. Masterful without being magisterial, this book's wise, gentle, candi...