On moonless nights, we don’t just do astrophotography to capture the night sky’s beauty. We also focus more on doing research work. The darker the skies, the more precise our measurements will be for astronomical observations in photometry.

As you may already know, the Al Sadeem Observatory provides astronomy professionals and experts a trove of image data of a variety of targets that they wish to focus on. This endeavor has been made official with the two observatory codes we received from the International Astronomical Union’s Minor Planet Center (M43) and the American Association of Variable Star Observers or AAVSO (OAAA) in 2019.

Right now, we’re collaborating with the Center for Astro, Particle, and Planetary Physics at the New York University – Abu Dhabi(NYUAD) and conducting a number of optical follow-up monitoring of X-ray binaries for Asst. Prof. David M. Russell, principal investigator for galaxy components at the Center.

We’ll be monitoring V4641 Sgr and MAXIJ1820+070 until the end of September, while the V404 Cyg monitoring is until the end of October this year.

Another separate research project via the @AAVSO on ASASSN-V J181654.06-202117.6 is also on-going.

We use our MeadeLX850 16” SCT mounted on Skywatcher EQ8 pro mount and SBIG STT-8300MM CCD camera, with standard RVB filters, to gather necessary data that often takes a couple of minutes to several hours for an effective time-series analysis of a particular target.

1. ASASSN-18ey (MAXIJ1820+070)

 

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You’re looking at one of our major research collaborations with the @nyuabudhabi . This is ASASSN-18ey (aka MAXIJ1820+070), a low-mass X-ray binary black hole transient about 10x the Sun’s mass. It is situated about 3 parsecs (parallax distance), or 9.8 light years, away from Earth in the Ophiuchus constellation. This research project is led by Asst. Prof. David Russell, assistant professor in NYUAD specializing in the multi-wavelength studies of black holes and neutron #stars. We took on the confirmation and time-series optical monitoring of this LMXB #blackhole system since its discovery in March 2018 by the All Sky Automated Survey for SuperNovae (ASAS-SN). For over a year, (April 2018 – October 1, 2019) we captured the X-ray binary’s variability—from its outburst, dimming, and re-brightening. It can be seen in the short animation prepared by our resident astronomer @aldrinb.gabuya. X-ray binary system outbursts in optical wavelength are typically faint (ranging between magnitudes +15 to +20), and are not visible to the naked eye. What makes ASASSN-18ey special is that its outbursts has been so bright that it’s easily detected in the optical wavelength. It reached its peak magnitude of +12.0V in March-April 2018, which gradually dimmed, and then went on its second outburst. #astronomy #abudhabi #uae #astrophotography #deepsky #research @uaespaceagency @universetoday

A post shared by Al Sadeem Astronomy (@alsadeem.observatory) on Sep 14, 2020 at 5:22am PDT

You’re looking at one of our major research subjects with the NYUAD. This is ASASSN-18ey (aka MAXIJ1820+070), a low-mass X-ray binary black hole transient about 10x the Sun’s mass. It is situated about 3 parsecs (parallax distance), or 9.8 light-years, away from Earth in the Ophiuchus constellation.

This research project is led by Asst. Prof. David Russell, assistant professor in NYUAD specializing in the multi-wavelength studies of black holes and neutron stars.

We took on the confirmation and time-series optical monitoring of this LMXB blackhole system since its discovery in March 2018 by the All-Sky Automated Survey for SuperNovae (ASAS-SN).

For over a year, (April 2018 – October 1, 2019) we captured the X-ray binary’s variability—from its outburst, dimming, and re-brightening. It can be seen in the short animation prepared by our resident astronomer Aldrin B. Gabuya.

X-ray binary system outbursts in optical wavelength are typically faint (ranging between magnitudes +15 to +20), and are not visible to the naked eye.

What makes ASASSN-18ey special is that its outbursts have been so bright that it’s easily detected in the optical wavelength. It reached its peak magnitude of +12.0V in March-April 2018, which gradually dimmed, and then went on its second outburst.

2. V4641 Sagittarii

One of our most recent collaborations with Asst. Prof. David Russell of the NYUAD is the monitoring of V4641 Sagittarii (V4641 Sgr), which only started this July 2020.

V4641 Sgr is another variable X-ray binary star system found in the constellation Sagittarius, and apparently the source of one of the fastest superluminal jets—or those that appear faster than light—in the Milky Way galaxy.

According to NASA, V4641 Sgr is the fourth known microquasar or a miniature version of the “massive, matter spewing black holes thought to exist in the centers of galaxies.”

When the hot gas that the V4641 Sgr’s black hole steals from its “normal” companion star builds up in a disk around it, V4641 Sgr produces a large outburst that can cause the system to shine much brighter than normal.

This X-ray binary was then believed to be the“nearest black hole to Earth,” with a distance of 1,600 light-years. But upon further studies, V4641 Sgr is now estimated to be 24,000 light-years away.

Experts are now trying to solve the mystery on why V4641Sgr acts strangely even for a black hole, as the explosions it creates fade within minutes, and appear at different times in different bands of light.

3. V404 Cygni

Another microquasar and binary system that we’re keeping our eyes on is V404 Cygni in the Cygnus constellation. We also began monitoring this last July 2020 for NYUAD’s Asst. Prof. David Russell.

As a binary system, V404 Cygni consists of a black hole (about 9x as massive as the Sun), and a “normal” star a little less massive than the Sun.

V404 Cygni has produced several “big eruptions” over the last eight decades. During the most recent one, astronomers even saw that the black hole is “dragging” space around it.

In 2015, V404 Cygni was observed to have an especially bright outburst in X-rays. But it wasn’t steady and consisted of a series of flashes that lasted for an hour.

Researchers in 2019 reported an interesting conclusion about V404Cygni’s outbursts—they found that the disk isn’t quite aligned with the black hole. As StarDate further explains: “The material in the inner portion of the disk is warped. As the black hole spins, its powerful gravity drags the space around it. That causes the inner disk to wobble.”

4. ASASSN-V J181654.06-202117.6

First observed by the All-Sky Automated Survey for SuperNovae (ASAS-SN) in February 2015, ASASSN-V J181654.06-202117.6 has now been identified as a “young stellar source undergoing an unusual dimming episode” in June 2020.

The following month, the AAVSO released an alert notice and requested monitoring for UXOR ASASSN-V J181654.06-202117.6.

The Al Sadeem Observatory—which obtained its official AAVSO observatory code (OAAA) in 2019—is currently participating in this endeavor spearheaded by Dirk Van Dam and Dr. Matthew Kenworthy of the Leiden Universityobservatory.

ASASSN-V J181654.06-202117.6 now shows a “very deep eclipse (0.8 mag ~ 50%), that is not only asymmetric (indicative of a circumplanetary disk) but also exhibits substructure (could possibly be rings, or indicative of moon formation),” according to the researchers.

Continuous monitoring of the potential young stellar object will enable experts to “catch the whole eclipse and constrain the period of the system.”

As a rule, follow-up observations of new ASAS-SN supernovae discoveries are conducted every time an important notice is issued, depending on its apparent position in the sky, and rate of significance.

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