HD 177765

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HD 177765
Sagittarius IAU.svg
Red circle.svg
Location of HD 177765 (circled)
Observation data
Epoch J2000.0 [1]        Equinox J2000.0 [1]
Constellation Sagittarius
Right ascension 19h 07m 09.77940s
Declination −26° 19′ 54.5064″
Apparent magnitude  (V)9.15 [2]
Characteristics
Evolutionary stage A5 SrEuCr [3]
B−V color index 0.45 [2]
J−H color index 0.071 [4]
J−K color index 0.055 [4]
Astrometry
Proper motion (μ)RA: -2.063 [1]   mas/yr
Dec.: −4.425 [1]   mas/yr
Parallax (π)2.5411 ± 0.0186  mas [1]
Distance 1,284 ± 9  ly
(394 ± 3  pc)
Absolute magnitude  (MV)1.55, [5] 1.166 [6]
Details [5]
Mass 1.81, 2.2 [7]   M☉
Radius 2.57  R☉
Luminosity 18.9, 26.9, [6] ~32 [7]   L☉
Surface gravity (log g)3.79  cgs
Temperature 7420, 7002, [6] 8000 [7]   K
Rotational velocity (v sin i)2.50 [8]  km/s
Age 955  Myr
Other designations
CD−26° 13816, CPD−26° 6650, Gaia DR2  6763969142066777344, HD  177765, SAO  187692, PPM  269324, EPIC  214503319, TIC  465996299, TYC  6882-1808-1, GSC  06882-01808, 2MASS J19070978-2619543, Renson 49550 [4]
Database references
SIMBAD data

HD 177765 is a white-hued star in the southern constellation of Sagittarius. With an apparent magnitude of 9.15, it is too faint to be seen by the naked eye from Earth, but is dimly visible using binoculars. [9] It is located at a distance of 1,284 light-years (394 parsecs) according to Gaia EDR3 parallax measurements.

Description

The star is classified as a rapidly oscillating Ap star (roAp star). It shows super-solar abundances of chromium and strontium as well as many rare-earth elements such as europium and cerium, but is depleted of carbon and nickel. [8] In 2012, the star was found to pulsate with a low radial velocity amplitude of 7–150 m/s and a period of 23.6 minutes, the latter being the longest out of any known roAp star at the time. [7] Two additional pulsation frequencies were detected in 2016. [10]

The precise stellar parameters vary from publication to publication, but the star is considered to be part of a group of evolved roAp stars with long pulsation periods, alongside β CrB A and HD 116114. The existence of this group implies a systematic shift of rare-earth emission line anomalies as roAp stars age. [7]

Related Research Articles

HD 1185 is a double star in the northern constellation of Andromeda. The primary, with an apparent magnitude of 6.15, is a white main-sequence star of spectral type A2VpSi, indicating it has stronger silicon absorption lines than usual, thus making it also an Ap star. The secondary companion, which is 9.08 arcseconds away, is not visible to the naked eye at an apparent magnitude of 9.76. It shares common proper motion and parallax with the primary star but orbital parameters are still unknown.

HD 30442 is a solitary star in the northern circumpolar constellation Camelopardalis. It is faintly visible to the naked eye with an apparent magnitude of 5.47 and is estimated to be 403 light years away from the Solar System. The object has a heliocentric radial velocity of −37 km/s, indicating that it is drifting closer.

20 Camelopardalis is a solitary star in the circumpolar constellation Camelopardalis. It has an apparent magnitude of 7.45, making it readily visible in binoculars but not to the naked eye. Located about 880 light years away, it is approaching the Solar System with a radial velocity of −50.3 km/s. Due to its faintness, 20 Cam is one of the 220 Flamsteed stars without Bright Star Catalog designations.

HD 63399 is an orange hued star located in the southern constellation Puppis, the poop deck. It has an apparent magnitude of 6.45, placing it near the limit for naked eye visibility. Based on parallax measurements from Gaia DR3, the object is estimated to be 445 light years distant. It appears to be receding with a spectroscopic radial velocity of 28.5 km/s. At its current distance, HD 63399 is diminished by 0.29 magnitudes due to interstellar dust.

HD 166066 is a solitary star located in the southern circumpolar constellation Octans. It has an apparent magnitude of 8.10, making it readily visible in binoculars, but not to the naked eye. The object is located 223 light years away from the Solar System, but is drifting away with a poorly constrained radial velocity of about 2.93 km/s.

HD 76270, also known as HR 3544, is a solitary, white hued star located in the southern circumpolar constellation Volans. It has an apparent magnitude of 6.10, making it faintly visible to the naked eye if viewed under ideal conditions. The object is relatively far with a distance of 2,360 light years, but is slowly approaching the Solar System with a heliocentric radial velocity of −2.6 km/s.

HD 155448 is a quintuple star system consisting of 5 young B-type stars. With an apparent magnitude of 8.72, it is too dim to be visible with the naked eye.

HD 1, also known as HIP 422, is the first star catalogued in the Henry Draper Catalogue. It is located in the northern circumpolar constellation Cepheus and has an apparent magnitude of 7.42, making it readily visible in binoculars, but not to the naked eye. The object is located relatively far away at a distance of 1,220 light years but is approaching the Solar System with a spectroscopic radial velocity of −27.3 km/s.

<span class="mw-page-title-main">HR 3831</span> Binary star system in the constelaltion Vela

HR 3831, also known as HD 83368, is a binary star system in the southern constellation of Vela at a distance of 233 light years. This object is barely visible to the naked eye as a dim, blue star with an apparent visual magnitude of 6.232. It is approaching the Earth with a heliocentric radial velocity of 4.0±0.3 km/s.

<span class="mw-page-title-main">HD 139319</span> Triple star system in constellation Draco

HD 139319 is a ternary system composed of the binary Algol variable star known as TW Draconis, and a main-sequence companion star at a separation of 3 arcseconds. The system lies in the constellation of Draco about 540 light years away.

<span class="mw-page-title-main">HD 199223</span> Double star in the constellation Delphinus.

HD 199223 is a double star in the equatorial constellation Delphinus. However, the system was originally in Equuleus prior to the creation of official IAU constellation borders. The components have a separation of 2″ at a position angle of 282° as of 2016. They have apparent magnitudes of 6.34 and 7.49 and distances of 354 and 359 light years respectively. The system is drifting closer with a radial velocity of −33 km/s.

HD 193721 is an astrometric binary in the southern circumpolar constellation Octans. It has an apparent magnitude of 5.77, allowing it to be faintly seen with the naked eye. Parallax measurements place the system 760 light years away from the Solar System and it is currently receding with a heliocentric radial velocity 8.6 km/s.

HD 193373 is a solitary red hued star located in the equatorial constellation Delphinus. It has an apparent magnitude of 6.21, placing it near the limit for naked eye visibility. Parallax measurements place it 846 light years distant and it is currently receding with a heliocentric radial velocity of 22.7 km/s.

HD 194612 is a solitary orange hued star located in the southern circumpolar constellation Octans. It has an apparent magnitude of 5.9, making it visible to the naked eye under ideal conditions. Parallax measurements place it at a distance of 760 light years and it has a low heliocentric radial velocity of 0.3 km/s.

HD 182509, also designated as HR 7370, is an orange hued star located in the southern constellation Telescopium. It has an apparent magnitude of 5.69, making it faintly visible to the naked eye if viewed under ideal conditions. Parallax measurements place the object at a distance of 635 light years. It has a poorly constrained heliocentric radial velocity of −5 km/s, indicating that it is drifting towards the Solar System.

<span class="mw-page-title-main">HR 1217</span> Star in the constellation Eridanus

HR 1217 is a variable star in the constellation Eridanus. It has the variable star designation DO Eridani, but this seldom appears in the astronomical literature; it is usually called either HR 1217 or HD 24712. At its brightest, HR 1217 has an apparent magnitude of 5.97, making it very faintly visible to the naked eye for an observer with excellent dark-sky conditions.

<span class="mw-page-title-main">HD 166473</span> Star in the constellation Corona Australis

HD 166473 is a rapidly oscillating Ap star and an α2 CVn variable located about 455 light-years away in the southern constellation of Corona Australis. It has the variable star designation V694 Coronae Australis. With an apparent magnitude of 7.953, it is too faint to be seen by the naked eye from Earth, but can be observed using binoculars.

<span class="mw-page-title-main">HD 861</span> Spectroscopic binary in the constellation Cassiopeia

HD 861 is a spectroscopic binary star system in the deep northern constellation of Cassiopeia. With an apparent magnitude of 6.622, the star is faintly visible to the naked eye under very dark skies and readily visible using binoculars. It is located approximately 403 light-years distant according to Gaia EDR3 parallax measurements, and is moving further away at a heliocentric radial velocity of 8.80 km/s.

<span class="mw-page-title-main">HD 197911</span> Star in the constellation Cepheus

HD 197911 is a bluish-white hued star in the deep northern constellation of Cepheus, close to the border with Draco and Cygnus. With an apparent magnitude of 7.669, it is too faint to be seen by the naked eye under most conditions, but readily visible using binoculars. The star is located some 3,020 light-years distant according to Gaia EDR3 parallax measurements, but is moving closer to the Solar System at a heliocentric radial velocity of −3.8±3.5 km/s.

<span class="mw-page-title-main">HD 24733</span> Binary star in the constellation Camelopardalis

HD 24733 is a spectroscopic binary system that is also a Beta Lyrae variable located about 606 light-years away in the deep northern constellation of Camelopardalis, close to the border with Perseus. It has the variable-star designation DD Camelopardalis. With a mean apparent magnitude of 7.038, it is too faint to be seen by the naked eye from Earth, but readily visible through binoculars.

References

  1. 1 2 3 4 5 Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics . 649: A1. arXiv: 2012.01533 . Bibcode:2021A&A...649A...1G. doi: 10.1051/0004-6361/202039657 . S2CID   227254300. (Erratum:  doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  2. 1 2 Høg, E.; et al. (February 2000). "The Tycho-2 Catalogue of the 2.5 Million Brightest Stars". Astronomy and Astrophysics. 355 (1): L27–L30. Bibcode:2000A&A...355L..27H.
  3. ↑ Renson, P.; et al. (19 March 2009). "Catalogue of Ap, HgMn and Am stars". Astronomy & Astrophysics. 498 (3). EDP Sciences: 961–966. Bibcode:2009A&A...498..961R. doi: 10.1051/0004-6361/200810788 . ISSN   0004-6361. Record for this source at VizieR.
  4. 1 2 3 "HD 177765". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 30 October 2024.
  5. 1 2 Glagolevskij, Yu. V. (2019). "On Properties of Main Sequence Magnetic Stars". Astrophysical Bulletin. 74 (1). Pleiades Publishing Ltd: 66–79. Bibcode:2019AstBu..74...66G. doi:10.1134/s1990341319010073. ISSN   1990-3413. Record for this source at VizieR.
  6. 1 2 3 Scholz, R.-D.; Chojnowski, S. Drew; Hubrig, S. (2019). "Strongly magnetic Ap stars in the Gaia DR2 Hertzsprung-Russell diagram". Astronomy & Astrophysics. 628. EDP Sciences: A81. doi: 10.1051/0004-6361/201935752 . ISSN   0004-6361. Record for this source at VizieR.
  7. 1 2 3 4 5 Alentiev, D.; et al. (1 March 2012). "Discovery of the longest period rapidly oscillating Ap star HD 177765". Monthly Notices of the Royal Astronomical Society: Letters. 421 (1). Oxford University Press (OUP): L82–L86. arXiv: 1112.4473 . Bibcode:2012MNRAS.421L..82A. doi: 10.1111/j.1745-3933.2011.01211.x . ISSN   1745-3925.
  8. 1 2 Ghazaryan, S; Alecian, G; Hakobyan, A A (19 June 2019). "Statistical analysis of roAp, He-weak, and He-rich stars". Monthly Notices of the Royal Astronomical Society. 487 (4). Oxford University Press (OUP): 5922–5931. arXiv: 1906.06984 . doi: 10.1093/mnras/stz1678 . ISSN   0035-8711. Record for this source at VizieR.
  9. ↑ Zarenski, Ed (2004). "Limiting Magnitude in Binoculars" (PDF). Cloudy Nights. Archived (PDF) from the original on 21 July 2011. Retrieved 6 May 2011.
  10. ↑ Daniel L., Holdsworth (18 October 2016). "Detection of new pulsations in the roAp star HD 177765". Information Bulletin on Variable Stars (6185). Information Bulletin on Variable Stars (IBVS): 1–5. doi: 10.22444/ibvs.6185 . ISSN   0374-0676.
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